If you find your vision unclear, you may think of checking the prescription and have a new pair of glasses. In fact, many people in Hong Kong mistakenly think that checking prescription is the same as the eye examination. A comprehensive eye examination does not only include checking prescription.
When blurred vision occurs, 70% of the causes are due to refractive problems, such as myopia, hyperopia, and astigmatism, but the other 30% are caused by eye diseases; to understand whether the posterior and anterior of the eyes are healthy, a comprehensive eye examination should include vision and refractive status measurement, eyes coordination and eye health examination.
A comprehensive eye and visual function examination is very important. If the vision is blurred, it may be due to refractive, eye health problems, or both. Computer-based refractive testing alone is not enough. It is necessary to check by optometrist or ophthalmologist to measure the refractive error. This is followed by binocular vision examination. We usually look at things together with both eyes. If there is a problem of strabismus, the vision can also be blurred. Finally, there is eye health examination. If any part of the eye has a lesion, it can also cause vision problems. Eye health examinations include eyelid, sclera, cornea, pupil, ciliary body, anterior chamber, lens, vitreous, retina, and systemic related eye diseases, such as diabetic eye problems. After the examination, the optometrist will also provide prescriptions and professional advice.
The general public may have considerable knowledge about diabetic eye problem, but we cannot ignore the effect of blood pressure on the body and eye health. High blood pressure is closely related to heart and vascular diseases. If the blood pressure continues to be high, it will increase the loading to the heart, which may cause a variety of complications, including stroke, coronary artery and renal diseases. The blood vessels in the eye will also have sclerosis, hemorrhage, and papilledema due to high blood pressure. These are collectively referred as "hypertensive retinopathy." Similar to diabetic retinopathy, hypertenisve retinopathy can also affect vision and cause permanent damage in the severe case. Both high blood pressure and diabetes affect the blood vessels in the eyes. The higher the blood pressure, the weaker the blood vessels in the eyes. Together with diabetes, the risk of retinopathy development will be larglely increased. I met a patient who had been suffering from diabetes for only a year, and his blood glucose level was only slightly higher. However, due to the high blood pressure, signs of diabetes began to appear in the eyes, and surgery was needed to prevent the condition from further worsening. Therefore, apart from controlling blood glucose level, we must also pay attention to the problem of high blood pressure.
To prevent diabetes and hypertension, it is best to start with diet control. Diet should have less salt, sugar, fat and cholesterol. People with diabetes should avoid putting too much sugar in drinks. Long-term consumption of too much salty or sweet food will increase blood pressure and blood glucose, affecting the health of the blood vessels of the body and eyes. As blood pressure and blood glucose are affected by the ingredients and portions of food, a balanced diet is very important. This will not only keep the blood pressure and blood glucose at a stable level, but also reduce the burden on blood vessels.
"Prevention is better than cure." Examination is also an important part of prevention. A comprehensive body and eye check should be done every year!
We can distinguish different colours owing to three types of cone cells at the retina, which respond to different wavelengths and transmit electrical signals to the brain for colour perception. However, if there is any missing type of cone cells or damage to the visual pathway, a person would have a decreased ability to see colour, and the condition is known as colour vision deficiency or colour blindness.
Many people may confuse colour vision deficiency with colour blindness. Colour vision deficiency means a person cannot identify certain colours, and of those red-green type is the most common type, and blue-yellow type is relatively uncommon. Most cases are congenital, but it can be acquired whose severity and type may vary with diseases, such as macular degeneration and optic neuropathy. The condition may be more prominent under dim environment or in light paints. Colour blindness is a rare congential condition which a person do not have the ability to distinguish colour, but only black-and-white vision of different intensity.
Colour vision deficiency is a relatively common vision problem. About 8% of males but 0.5% females may have the deficiency. To date, there is medical treatment to cure colour vision deficiency or blindness. Although this condition does not significantly affect one’s daily life, people may have difficulty in differentiating colours in their lessons, or in engaging in certain occupations that require colour perception, for example, police officer, pilots, or laboratory technician. Therefore, if people have any enquiries, they should seek the advice(s) from optometrists. If parents find their child having colour vision deficiency, they should give guidance and confidence, inform the teachers, and encourage the child to select their future career properly.
Myopia (near-sightedness) is affected by genetic and environmental factors. Myopic children’s parents often worry about fast progression, and the consequences of high myopia are not only to wear a pair of eyeglasses with thicker lenses, but also more prone to different eye diseases, such as glaucoma and retinal detachment. Therefore, parents often ask: "What can we do to slow down the progression of myopia?"
In the past decades, researchers have investigated and published numerous studies on the methods of myopia control, and the results are summarized as follows:
- Progressive addition lenses (PAL): Although there was statistically significant reduction of rate of myopia progression in using PAL over normal single vision lenses, the actual difference (approximate 0.25D in 3 years) was clinically insignificant.
- Executive prismatic bi-focal lenses: This lens design could reduce the myopia progression rate by approximately 50%. Children should use the lenses with care as the upper portion is used for far vision and lower portion, for near reading. In addition, there is a marked horizontal line separating the upper and lower zone, some parents and children have hesitation to accept the cosmetic outlook of the lenses.
- Defocus incorporated multiple segments lenses (DIMS): The centre part (9.4mm diameter) of the lenses is the child’s myopic correction. Numerous defocus circles are placed outside this zone to create images in front of the peripheral retinal, these defocus images thus interfere the signal for elongation of eyeball, and hopefully can retard the myopic progression. Study showed that this lens design could slow down myopic progression by approximately 52%.
- Defocus incorporated soft contact lenses (DISC): By combining normal myopic correction and defocus rings, the DISC allows the far image clearly focusing on the retina, and at the same time creating a defocus image at the peripheral retina to control the growth of eyeball (myopia progression). Study showed that this method could slow down myopic progression by approximately 60% if the children wore the contact lenses for 8 hours per day.
- Orthokeratology (OK lens): Results showed that the progression of myopia has retarded 50 % in children with OK lens when compared with children wearing eyeglasses.
- Ophthalmic drugs: Results showed that the effects of myopia could be effectively controlled, but side effects (e.g. pupil enlargement and loss of near focus function, etc.) cause inconvenience to the children, and there are no publications about the side effects of long-term use of these medicines in children.
- Other alternative therapies (e.g. pinhole glasses and visual training): There are no formal studies to support the effectiveness of myopia progression.
If your child has fast progression in myopia, you must study and understand the pros and cons of different methods before choosing a treatment for them. Remember the 20-20-20 rule to protect their vision, take a 20- second break to look at something 20 feet away after 20 minutes near tasks. In addition, outdoors activities also play important role in control the progression of myopia.
Some parents suspected their children suffering from squint because they noticed their children often watching TV with face turn or head tilt. In fact, looking things at sideways can be
1) a bad habit or;
2) a significant difference in vision between eyes or;
3) caused by squint or other reasons, it cannot be simply say the kid has squint when he turns his face to one side.
So, what is squint (strabismus)? There are two types of strabismus, it can be manifest (tropia) or latent (phoria). Both tropia and phoria can be external (exo); internal (eso); upward (hyper) or downward (hypo) deviation. Strabismus is mostly due to extraocular muscles dysfunction, weakness on the coordination of the extraocular muscles or uncorrected high hyperopia. Strabismus is more prevalent in children born prematurely, with cerebral palsy or edema or family history of strabismus. If you find one of the eyes of your child looks in a different direction when he is looking straight ahead, it is likely that he is suffering from strabismus. However, pseudo-strabismus especially pseudo-esotropia is quite common in young children. It occurs in babies with a wide nasal bridge and prominent upper lid (epicanthal) folds, part of the conjunctiva near the nose (nasal side) are covered by the folds making the eyes looks internally squinted. It is not easy for parents to differentiate it from real esotropia.
Optometrist can diagnose children through some assessments whether a child is suffered from strabismus. If you are in doubt, don’t wait, take your child to have a comprehensive eye examination!
Besides cosmetic concerns and adverse impact on the self-esteem, strabismus may possibly lead to amblyopia, both of them can negatively affect the development of stereo acuity and depth perception. Strabismus may cause double vision in some cases too. Certain types of strabismus may cause fatigue and headache during reading. Thus, strabismus may give negative impact on children's daily life, learning and sports performance.
Strabismus can be managed by eyeglasses; vision therapy and surgery, depends upon the type and severity, combination of treatment may be needed in some cases. Eyeglasses may help to relieve the angle of deviation if it is caused by uncorrected hyperopia. Vision therapy strengthens the alignment of the eyes by enhancing the sensory fusion and oculomotor control. Adjusting the strength and the attachment point of the extraocular muscles by surgery (done by ophthalmologist) may help the eyes position returning to normal. If amblyopia is present, the child should also be treated by occlusion therapy.
In conclusion, children under 8 years of age is in critical period of vision development, early detection gives better treatment outcome. Be a smart parent, take your child for an eye checkup now!
"My friend’s kid is at the same age as mine, he can walk, but my kid can’t, is there any problem?" "My kid inherited my talent! He learned to talk so early. " "Your kid looks so tall!” The physical appearance or behavior can easily be compared; however, the development of the eye is carrying out quietly, we might overlook it easily.
It's great to bring your child into this wonderful world. But when they open their little eyes, it is not yet known whether they can really see everything well in the world. The maternal age; maternal health status; the delivery process; the birth weight and the gestational period …etc. will influence the development of the child’s eye and vision in the future.
The size of the eye of newborn babies is about 60% to 70% of that of adults, while the age of 0 to 8 is the critical period for visual development in children. Newborn babies can only see light and shadow at first few weeks, but their vision develop rapidly in the first year of life and reach adult vision at about four to five years old. The process involves both the development of the eyes and visual center in the brain, if there is any condition causing blurry vision or abnormal binocular vision, such as congenital glaucoma, cataract, high refractive error or squint, the child can end up with visual impairment. Many congenital eye diseases occur earlier than a child being able to express themselves.
Parents can be aware of some special signs and symptoms such as too big or too small eyeballs, tearing eyes, excessive secretions, unnatural blinking, excessive eye rubbing, red and swollen eyes, habitually looking things at sideways or very close up distance, eyes cannot move smoothly or consistently. Early detection gives better treatment outcome. If parents find their children having some of the above symptoms, they should take them for a comprehensive eye examination as soon as possible.
Did you realize that the distance or spatial orientation of an object appeared different as you closed one eye? When you covered your eyes alternately, did you notice that the position of an object through the right or left eye is different from each other? This phenomenon is due to the difference in position of the two eyes which results in the discrepancy in the image perceived by each eye. When the images from our left and right eyes reach our brain, they will be combined into a single perception. This is why an object is seen as “stereo”. This creates the spatial perception or so called “stereovision”.
After birth, stereovision will “build up” and “mature” with time. Newborns start to develop spatial perception by around 3-5 months old. By around 6 months old, stereovision will reach adult level. However, some factors may hinder the development of stereovision, including strabismus or un-corrected refractive error with significant difference between eyes. These factors can cause amblyopia and affect the ability to view with both eyes at the same time and thus affecting the development of stereovision. Without stereovision, the judgement of spatial orientation and distance will not be accurate. This can affect one’s performance in ball games as he or she may not be able to accurately judge the positon and distance of a ball and hence affecting the performance of catching or hitting. A person without stereovision cannot perceive the stereo images in a 3D film even he/she is wearing a stereo googles. In addition, the lack of stereovision may limit their occupational choices e.g. pilot or athlete.
It is very important for children to have a comprehensive eye examination. It is because children before 8 years old is at the critical period of eye development. We should find out the underlying cause of poor stereovision in children and provide vision training so as to enhance the coordination between the two eyes. However, if the problem and underlying cause is not detected until adult time, the stereovision may not be able to recover.
Some parents reported that their child have problem of skipping lines during reading. Are they not paying attention? Are there any other causes?
Reading ability and visual function are closely associated. To investigate the problem in reading, we must first know whether a child has up to standard vision. Refractive error e.g. high hyperopia, myopia or astigmatism can make vision not clear enough for reading. This need to be corrected by spectacles. We should also check whether a child has normal binocularity. Binocularity includes the ability of both eyes to accommodate for adjusting focus and to move as a team. When reading, we need to have adequate accommodating ability. This accommodating ability of our eyes works similarly as a camera lens that changes its focusing power in order to get a clear image. Inadequate or excessive accommodating ability creates blurriness and hence affects a child’s reading performance. In addition, our eyes need to turn slightly inwards in order to get a clear and single image of an object at near. If the ability of eyes turning inward is weak, a child will easily feel tired when reading and lead to problem of skipping line.
Visual tracking skills is also important for reading. Visual tracking skill involves the ability of both eyes to follow a moving object smoothly and to accurately change focus from one point to another. If the eyes cannot follow each words in a passage smoothly or have inaccuracy in changing their position from one word to the next, a child will lose their place during reading. Lastly, we have to understand whether the child has adequate reading comprehension skills. Without adequate reading comprehension skills, a child may have problem understanding the content and skipping word or line.
Good visual function enhances our reading ability. If you find that your child frequently shows problem of skipping lines during reading, you should bring your child for a detail eye examination. A detail eye examination can help to find out the underlying cause so that appropriate treatment can be offered, including spectacles prescription and visual training. To conclude, reading is far more than just seeing clearly. Accurate accommodating ability, binocularity, visual tracking skills and cognitive skills are all essential elements in reading performance that should not be overlooked.
Nowadays, it is not difficult to find children wearing glasses on the street, this phenomenon really worries many parents. There are several reasons why children should wear glasses.
First, short-sightedness (myopia) is a common vision problem in Hong Kong. Short-sightedness is due to the elongation of eyeball. Owing to long eyeball, the image of object at far distance will be focused in front of the retina, such children will complaint of blurry distance vision. Wearing appropriate corrective lenses will make them see clearly again.
Second reason is far-sightedness. In fact , most young children have low degree of far-sightedness, and they are capable to focus distance and near object clearly . But if a child suffers from high degree of far-sightedness, both distance and near images can be blurred, spectacles correction is needed. Since children with far-sightedness do not have obvious symptoms, parents can easily ignore the existence of such. If the situation is serious and the far-sightedness is not detected and corrected promptly, the is chance in getting amblyopia (weak eyesight) will increase.
The last common cause is astigmatism. Astigmatism is due to the asymmetric curvatures of the cornea. In fact, most children have varied degree of astigmatism at birth and gradually decline as they grow. If a child suffers from moderate or high astigmatism, it will lead to blurry vision and spectacles correction is required.
Most children do not know how to express their visual function to the parents. Preschool kids is in their critical period of visual function development, so parents are advised to take children to an optometrist for comprehensive eye checkup before the age of 3 years old. We hope all our children can have a healthy "soul window" to see the world.
Many parents pay more attention to their children's eye health, so the age of children who go to the eye clinic for checkup are getting younger and younger. Don't think that young kids will have more problems in the eye examination process, in fact, many parents are very shocked on their children who can work so well with the optometrists during the eye examination. Many one to two years old children are capable to complete tests such as refractive errors, binocular vision and ocular health examination.
We remember once, a parent found his two-year-old child, like to read and watch TV at a closed-up distance, so they took him for eye examination. Before the checkup, the child was held tightly by his mother, but he did not look around curiously like other children, nor get the toy next to him. When we started the examination, the mother let go of his hand, no matter how hard we did to cheer him up, he was just crying. Mother reported that the child was very timid since childhood, he felt frightened in strange places. After painstaking processes, we finally completed the examination, and found the child was suffered from severe short-sightedness (myopia) and external squint.
Congenital eye diseases include high myopia, far-sightedness (hyperopia), congenital cataracts or retinopathy...etc. We occasionally found young children with congenital eye diseases. These children usually show fear in strange places and we need more care and time to communicate with them in order to reduce their fear. Since they cannot see clearly, they will feel highly insecure, and easy to cry and have timid behaviour.
Parents should not think that children are too young for an eye checkup. Early examination and treatment can increase the chance in improving the vision, and clear vision is important for a child to build confidence.
For the case mentioned above, the boy’s vision had improved significantly after wearing glasses and some vision training. During the follow up visits, he became more and more lively, and now he is no longer timid.
Our eyes can move smoothly with the use of the six pairs of extra-ocular muscles. If there is a problem in the muscles or the cranial nerves that controlling them, it may lead to double vision (diplopia).
Diplopia refers to seeing two images of an object at the same time. Many people think it is due to refractive errors like myopia and hyperopia. In fact, the blurriness caused by the uncorrected refractive errors will not cause double images. Refractive errors only create scattering of a single image, which can be eliminated by wearing appropriate corrective lenses.
Double vision can occur with one eye (monocular) or both eyes (binocular), while the former is less common.
Reasons for kids seeing double vision include: squint, extra-ocular muscles are too strong or too weak; too long or too short. They can be improved by visual training or surgery. However, we have to pay special attention for a sudden onset of persistence double vision in adults. It may be related to eye or brain problems, for example, dislocation of crystalline lens and keratoconus, can lead to double vision with one eye. Further, nerve problems in the brain or head trauma, etc. can affect the eye muscle control and cause double vision with two eyes. Other systemic diseases, like nasopharyngeal carcinoma, severe Diabetes Miletus, or Thyroid problem, etc., can also be the reasons of diplopia.
If you experience double vision, you should consult an optometrist for a comprehensive eye examination as soon as possible to find out the cause and receive proper treatment.
Infants from birth to 6 months of age may experience eye turn, called “crossed eye”. It is because the brain and eyes are not in harmony. This condition will disappear after 6 months old. If it persists, parents should bring them to see an optometrist for a comprehensive eye examination.
Then why do older children also experience crossed eye? It may be due to high degree of uncorrected far-sightedness (hyperopia), a big difference in refractive errors between two eyes (anisometropia), imbalanced muscles, restricted eye movement or rarely due to eye diseases like cataract or cloudy cornea, etc. If it is related to refractive error, it can be corrected by spectacle correction. There was a kid with high degree of hyperopia, +7.50 D in the right and +9.00D in the left. His parents reported he only used his right eye to see, while the left eye turned in. After a detailed eye examination by an optometrist and wearing a suitable spectacle correction, his eye turn disappeared! For eye muscle imbalance or restriction problem-related eye turn, a proper visual training or squint surgery may be needed.
Contact Lens Fitting
In summer, more people choose to wear contact lenses instead of spectacles, but how much do you know about wearing contact lenses?
Q: Can I wear contact lenses during swim?
A: Yes, but it is necessary to wear swimming goggles and preferably to use daily disposable contact lenses to avoid water from contaminating the lenses, and the lenses should be removed immediately after swim.
Q: Should we put on the make-up first or wear the contact lenses first?
A: "Wear contact lenses first, then do the make-up, remove the contact lenses and then remove the make-up" because the composition of cosmetics and makeup remover is difficult to remove after get contact with fingers, which may easily contaminate the lenses.
Q: Is it possible to sleep with contact lenses?
A: Maybe. Some contact lens with high oxygen permeability do allow wearer to sleep with contact lenses on, however sleep with low oxygen-permeable lenses can lead to cornea hypoxia, or even inflammation; so, you better consult your optometrist first if you want to take nap with your contact lenses.
Q: Is all over the counter eye drops could be used during contact lens wear?
A: No, the ingredient and preservatives of the eye drops may not suitable for everyone, you should consult your optometrist first.
Q: How can I wear my contact lenses healthily?
A: "Maintain personal hygiene, clean the lenses and accessories every day, and have regular check up with your optometrist." Clean and dry your hand before handling your contact lenses. Lenses need to be cleaned and disinfected every day after wear; Clean the lens case and accessories every day, disinfect the accessories every week and replace them regularly.
"Three feet of ice does not form in a single day ", many contact lens problems are caused by improper lens care procedures. Have regular check up with your optometrist and follow his instructions, make sure all the problems can be detected earlier, wearing contact lenses can be very safe and healthy.
When you are get used to wear contact lenses, are there any lens care procedures you've been ignored?
Q: I have been wearing contact lenses for over ten years, what do I needed to pay special attention for?
A: No matter how long your contact lenses history was, it is important to remember to have regular eye check. Optometrist will assess your ocular health and tell you whether the contact lens is still suitable to you, whether the contact lens care procedure is still correct, and so on. In addition, you can also consult your optometrist from time to time about the needs to refit other lenses for better visual performance and health, for example when you start to have reading or dryness problems, you may need to refit with a progressive contact lens or contact lenses with less water demand respectively.
Q: Do I need to put the contact lens solution in the freezer to keep them fresh?
A: Refrigeration may affect the disinfection function of contact lens solution. After using them, you should simply cover the solution tip properly, place it in a dry and cool place, and never in a freezer and humid place, such as a washroom and bathroom.
Q: What is the difference between saline and multi-purpose contact lens solution?
A: Saline does not have any disinfection function and only should use for lens rinsing. Multi-purpose contact lens solutions can use to clean, disinfect and store the lenses.
Q: There are many multi-purpose contact lens solutions in the market marked ‘no rub’, Are they really can clean the lenses without rubbing?
A: Only lens rubbing can remove the deposits from the lenses surface and clean the lenses.
Q: Can the multi-purpose solution be reused after lens storing?
A: Because after each disinfection, the disinfection effectiveness of the multi-purpose solution will be rapidly reduced, so the solution cannot be reused.
Some people will treat color cosmetic contact lenses as a beauty tool, however, improper use of these ‘beauty tool’ will not only affecting the wearer’s appearance, but also may cause permanent visual impairment to their eyes. So, what do you need to pay attention when choosing and using the colored contact lenses?
There are many color contact lenses available on the market, their lens materials and the color dye are affecting their quality, oxygen permeability and wearing safety. Therefore, in addition to choose a nice color, wearers also need to pay attention to the lens fitting and product safety. To ensure the lenses were suitable to your eye, a proper contact fitting must be performed by optometrist before wearing them. If the lens is too loose and causing excessive lens movement, the eye may appear to be squinted and vision may be affected. On the contrary, if the lens is too tight, it may cause eye discomfort, corneal hypoxia and even corneal damage.
If you order contact lenses online, there will be no proper eye check, fitting assessment and follow-up assessment before the order, so remember not to order any contact lenses online.
To enhance the appearance of your eyes, in addition to using suitable contact lenses , you should strictly follow the instructions by the optometrist, clean the lenses daily after use, replace the lenses regularly and have eye examinations with your optometrist accordingly. Clean lenses can reduce the risk of hypoxia and red eye, and reduce the chance of corneal infection. If you use the cosmetic lens correctly, then you will be able to enjoy the fun of wearing color contact lenses.
Is it true that people who are in their forties and suffered from presbyopia (the reading problem caused by reduced in accommodation ability) need to stop contact lenses wear?
As you get older, your eyes conditions change accordingly, for example, with less tear secretion. But with proper contact lenses selection and fitting assessment, even if you are suffering from presbyopia, you may still able to wear contact lenses. The following three are common ways of presbyopia correction using contact lenses:
- Look at distant/near things with contact lenses, and then look near/ distant things with spectacles.
- Adjust the power of contact lenses to make one eye works for distant vision, and the other eye for reading (Monovision).
- Wearing progressive contact lenses
The above methods have their advantages and disadvantages, and optometrist will make different recommendations according to your daily needs.
Using the first way to correct presbyopia, the user still needs to wear spectacle for some daily tasks. If you don't want to wear spectacles at all, you may consider using the second or third methods, but the second method is generally suitable for people with early presbyopia. Nowadays, the progressive contact lenses available can allow seeing distant and near things using the same lenses, although the design and manufacture technology of lenses is becoming more mature, and more lens choices are available, but the parameters of these contact lenses are still having some limitation, and it is necessary to check and choose the best combination of lens parameters that fit your eye. Like wearing progressive spectacles, using progressive contact lenses need adaptation, but after you get used the lens, it is not easy for others to notice your reading difficulties.
Those who are interested in wearing progressive contact lenses should consult your optometrist first. And the successful outcome really depends on your ocular health and personal expectations.
About 70% of Hong Kong's school children suffered from myopia, apart from spectacle, can children choose contact lenses? In fact, if they are suitable, wearing contact lenses can indeed bring a lot of convenience to children in their daily lives, such as doing outdoor activities without spectacle. However, contact lenses may not suitable for everyone, so examination must be done by the optometrist to assess the ocular refraction, corneal curvature, ocular health and lens fitting before prescribing the contact lenses. The main difference between wearing contact lenses and spectacle is that contact lenses will stay on the corneal surface, if it is not handled properly, it will easily cause problem to the ocular health. Although wearing contact lenses has certain risks, the risks can be greatly reduced by proper use and care.
Before deciding whether to allow their child to wear contact lenses or not, parents must also consider their children's habits, self-care abilities and understand their purpose of wearing contact lenses. Besides the heavy classroom work, children in Hong Kong also have to take part in different extracurricular activities. If contact lenses are used, how long will the child need to wear it every day? How is his personal hygiene? Can he handle contact lens care on his own? At home, he can always ask his parents or domestic helper for help, but at school or elsewhere, children have to handle contact lenses on their own. Therefore, when parents asking their children to wear contact lenses, they must be sure that they are willing to take the time to handle and clean the lenses.
Contact lenses must be used according to optometrist recommended wearing time, Wearer should not rely too much on the lens and wear it for too long, if the child's activity time is long, they may need to use spectacle for some occasions. When working at home, try to encourage children to use spectacle. Contact lenses must be removed before sleep, short nap and before taking a bath. Children may need parental assistance during lens wear, so parental participation and support are important elements of success. Parents and children both need to learn how to clean and care the contact lenses together and learn how to deal with special situations, such as lens dislocation or broken lenses, as these are the problems they may encounter when wearing contact lenses. When there is any eye discomfort, red eyes, etc., they should immediately stop contact lenses wear, and visit optometrist for checking. Most of the contact lenses wear complications are caused by improper lens care and cleaning, and regular eye examination can allow early detection of problem and early management, so regular contact lens aftercare visits and review of care procedures are the most important and necessary matters to ensure the health of children's eyes.
In concluded, children are suitable to wear contact lenses or not, was not limited by their age, but depends on if their eye condition is suitable for wearing contact lenses? If they are able to responsible for the lens care? Are they willing to use it? Is there any parental support, and whether they can follow the instructions from optometrist?
We may sometimes find the contact lens advertisement promoting “silicone hydrogel lenses”. So what is "silicone hydrogel"? What is the difference between wearing a silicone hydrogel lens and a hydrogel lens? What should a contact lens wearer pay attention to when choosing lens materials?
Hydrogel is the main material used to make soft contact lenses. It is a kind of plastic material contains water. Due to its compatibility with natural tissues, it is also widely used in other medical fields. The water in hydrogel lens helps to transport oxygen in air through the lens to the cornea. The water content of the hydrogel contact lens is 38 to 72%. The higher the water content, the better the ability to transport oxygen. To increase the oxygen permeability of the lens, the water content of the lens needs to be increased. But when increasing the water content of the lens, the stability and toughness of the lens is reduced. Silicon is a material with high oxygen permeability without water component. Adding silicon to hydrogel can increase the oxygen permeability without increasing the water content of the lens, maintaining the stability and toughness of the lens. Therefore, silicone hydrogel lenses are regarded as lenses with better corneal health. When choosing contact lenses, contact lens wearers should note that switching to silicone hydrogel lenses may only help solving problems that related to corneal hypoxia, but not other contact lens complications. In addition, silicone hydrogel lenses are relatively stiff, there may be lens sensation when first worn. The cost and selling price of silicone hydrogel lenses are generally higher than that of hydrogel lenses, and not all contact lens solutions are suitable for storage or cleaning silicone hydrogel lenses. Before choosing any lenses, contact lens wearers should consult the opinion from optometrists.
Optometrists encounter contact lens wearers every day. Some of them follow the instructions and recommendations from optometrists, but some of them use contact lenses wrongly with various reasons.
Recently, author conducted a study on contact lens accessories contamination by bacteria. We found that many contact lens wearers often mishandled contact lenses. For example, when handling the lenses, some participants used saline to soak the contact lenses which is without any disinfection effect. Many of them did not disinfect the contact lens cases. Even though more than half of the contact lens wearers claimed they did clean the case, but nearly half of them did not use any cleaning agents, so how can they clean the cases thoroughly? Other participants did not regularly disinfect or clean the contact lens case because they forgot to do, found it inconvenience or troublesome, or considered as not important. In addition, not regularly changing the lens case or pliers is also a common problem. Nearly 80% of the participants said that they would renew the contact lens case when a new one was included with the contact lens solution, 10% would replace it every three to four months. However, 10% of the participants said that they would only replace the case when they found it was dirty. Everyone knows that bacteria are invisible to the naked eye, so why the participants know their boxes are contaminated? These negligent participants' contact lens accessories are far more likely to be contaminated with bacteria than the users who follow the instructions.
To wear contact lenses comfortably and safely, the expertise of an optometrist is necessary, but the wearer’s compliance is also important. Even if you are using disposable contact lenses, proper lens and accessories care is still very important, because many eye discomfort or inflammation problems are caused by the deposit accumulation of the lenses. In addition to the care procedure, remember to visit your optometrist for regular contact lens check up every six months.
"Which soft contact lens is the best?" While asking this question, we must first note that contact lens with best quality may not necessarily the most suitable for you.
In fact, the quality of most of the soft contact lenses available in the market is good, so the key of choice is the wearing schedule. Disposable lenses (daily to monthly replacement) can greatly reduce various problems caused by lens deposits. Compared with conventional soft lenses, the wearing pattern of disposable lenses is better for eye health. Of course, some wearers neglected the daily cleaning and disinfection of lenses because they switched to disposable lenses, which is another matter.
On the other hand, the higher the water content of soft lenses, the higher the oxygen permeability. The problem is that when the water content of the lens is higher, the water will evaporate faster, which in turn causes dry eye problems. So when fitting contact lens, Optometrists must first check the tear condition of the potential wearer. Fortunately, the materials of contact lenses improve with time. The silicon hydrogel contact lenses has brought good news to many contact lens wearers. Since silicon itself has a very high oxygen permeability without water component, it can greatly improve the oxygen permeability of the lens while maintaining a low water content. It is because each person's eye conditions are different, this type of silicone hydrogel lens may not fully meet everyone's needs.
How to take a balance point in response to various factors and needs is a subject. The next time you try contact lens, you don’t have to ask which contact lens is the best, but "Which contact lens is the best for me?"
If you ask people who wear contact lenses whether they have eye check with optometrists regularly or not, most of them replied: "Of course!" In fact, contact lens wearers generally have higher chance to find an optometrist than people who wear glasses. It is because they will more or less encounter some problems related to contact lenses wear, such as red eyes, feeling dryness, decreased vision or comfort, etc., hence they will seek advice from optometrists.
Secondly, when the lenses are due to replace for some non-disposable lens wearers, or those who wear disposable lenses are about to run out of "stocks", they will find optometrists to check the suitability of current contact lens, such as contact lens power and ocular health. However, does it mean a comprehensive eye care?
In fact, the above mentioned only check the vision and the health of the front part structure of eyes, such as cornea, conjunctiva, eyelid, etc. However, the overall eye structure is much more than that. One of the most important parts is the retina. The vast majority of contact lens wearers belong to the myopia family, and high myopia is one of the major causes of retinopathy. It is because the eyeballs of myopic patients are generally longer than normal eyes, the retina will be pulled thinner, and the pulling force between the vitreous and the retina is greater. These factors will increase the chance of defects in the retina. In severe cases, it may even induce retinal detachment and permanently impaired vision.
If you are wearing contact lenses, please keep in mind that in addition to contact lens care examinations, you must also seek for comprehensive eye examination on a regular basis. Let the optometrist dilate the pupils to examine the fundus in detail. If there are any retinal problems found, it can be detected early and treated properly as soon as possible.
Contact lens technology is keep changing with time, and we can see different new terms used in advertisement of disposable contact lenses, including high oxygen-permeable materials, highly effective moisturizing ingredients, and "high-resolution" aberration control technology. The new contact lens technology undoubtedly improves the comfort of wearing, but can everyone wears contact lens healthily?
Some disposable contact lenses wearers purchase contact lenses without checking, thinking that as long as they do not feel uncomfortable, their eyes may be already get hurt. In fact, to wear disposable contact lenses healthily, we must first find out which type of contact lens is suitable for us. In addition to whether you feel discomfort after wearing the lens, it should also be examined objectively, including checking the position, movement and tightness of the contact lens. Proper fitting examination can avoid eye health problems caused by improper wearing. For example, tight-fitted contact lenses are more likely to cause corneal or conjunctival damage and neovascularization. Therefore, contact lens fitting check is the first step of healthy contact lens wear.
The advantage of disposable contact lenses is to maintain the oxygen permeability and hygiene of the lens by regular replacement. Many people often only focus on high oxygen permeability of the contact lens, and ignore the proper wearing schedule and care regimen. Some of the disposable contact lenses and conventional contact lenses are made of hydrogel. Their oxygen permeability depends on the thickness and water content of the lens, so disposable contact lenses are not necessarily with higher oxygen transmissibility than conventional contact lenses. If you wear disposable contact lenses too long, your eyes may also suffer from hypoxia, leading to corneal edema and neovascularization. In addition, all non-daily disposable contact lenses need to be cleaned and disinfected. If the lenses are not properly cleaned and disinfected, the eyes may also suffer from allergies and infections.
In fact, as long as we follow the instructions from optometrist, wear the contact lens that suits us, take proper care procedures for the lens, and have follow up regularly, we can wear disposable or conventional contact lens healthily.
Many contact lens wearers of over 10 years might have heard a saying that: people can wear contact lenses for 10 to 20 years at most. Is it true, or just a hearsay?
In the old days, contact lens wearers usually use conventional soft contact lenses (mostly with annual replacement). The oxygen permeability of those materials is generally low. And the deposit and debris on the lenses may further decrease the oxygen permeability, exacerbating the problem of cornea hypoxia, and resulting in corneal neovascularization and physiological changes of corneal endothelium. If the situation worsens, the contact lens wearers can no longer wear contact lenses. Therefore, it is believed that people can wear contact lens for a maximum of 10 to 20 years.
Nevertheless, with the advent of the hyper-permeable material, silicone hydrogel, and the popularity of frequent replacement soft contact lenses, the problems caused by the old generation of soft contact lenses have been resolved. In recent years, there are more options of daily disposable silicone hydrogel contact lenses with various designs, making healthy contact lens wearing available for people with different needs. More importantly, contact lens wearers should consult optometrist regularly to check contact lens wearing status and ocular health. As long as the contact lens wearing is maintained in a healthy way, people at all age groups do not have to worry about the maximum period of contact lens wearing.
Have you ever heard a kind of contact lenses that you can wear at night, take it off when you wake up, and have good vision during the day? This kind of lens is called "orthokeratology" (or "orthok") lens. It is different from the regular contact lenses. Most orthok lens wearers are myopic children rather than adults. Children wearing orthok lenses, in addition to correcting their vision, also hope to slow down the progression of myopia. Studies published in the early years from the School of Optometry, the Hong Kong Polytechnic University showed that children wearing orthok lenses have a reduced myopia progression rate that is half as slow as those using regular glasses. Recent studies in the United States also have similar results.
Because orthok lenses need to be used during sleep, and children's sleeping time is usually more regular than adults, the orthok effect will be more stable and optimum. Studies have pointed out that most children under 4 dioptres of myopia who use orthok lenses can achieve clear vision even they don’t wear glasses during the day. Certainly, the visual outcomes after the orthok lenses varies from person to person. As orthok can slow down and reduce myopia at the same time, it is a method of choice nowadays for the parents and children for controlling myopia.
Although orthok have its benefits, like regular contact lenses, proper handling and use are particularly important. Earlier reports have suggested that improper wearing of orthok lenses can cause eye inflammation or infection. In fact, the key of success depends on the cooperation between the wearer and the optometrist. As long as the orthok lenses are properly fitted and used in accordance with the instructions, plus attending the scheduled regular follow up, the risk of orthok wear is very low. Frequent follow up visits, sometimes required in the morning, often make parents and children feel inconvenient, but this is necessary for children to wear orthok lenses safely and comfortably.
Q: Will wearing orthok lenses sleep cause corneal hypoxia?
A: Orthok lenses must be made of rigid lens materials with high oxygen permeability which meet the minimum oxygen permeability standards for overnight use, in order to maintain the highest oxygen supply to the cornea when the eyes are closed. In addition, during the initial and some subsequent follow up visits, the optometrists will arrange eye examination for the children in the morning to ensure that there is no corneal hypoxia. In cooperation with correct use, proper cleaning procedures and regular follow-up by optometrists, corneal hypoxia caused by wearing orthok lenses at night is not common.
Q: Will wearing orthok lenses cause corneal damage?
A: If the orthok lenses are properly fitted, the lens removal method and lens care procedures are appropriate, the chance of epithelial damage of cornea is very small. The optometrists will regularly arrange eye examinations and pay attention to whether the children insert and remove the lenses correctly. If the cornea is damaged, the optometrists will advise to temporarily stop wearing the lenses until the cornea is healed; and solve the cause of corneal damage before using the orthok lenses again. If the corneal health problems are identified and managed in the early stages, the chance of corneal damage is minimal.
Q: Is it easy to get keratitis when wearing orthok lenses? What should I do if I get infected?
A: Keratitis occurs only when there is a defect in the corneal epithelium, a decrease in resistance, and the presence of bacteria. The main cause of infection is often associated with improper cleaning and care of the contact lenses. Therefore, the wearers must thoroughly clean and disinfect the lenses after daily use, perform protein removal procedures every week, have regular follow up and have regular replacement with new lenses. If you experience tearing, red eyes, eye pain, photophobia, etc, stop wearing the lenses immediately and seek your optometrist for help.
In conclusion, under the premises of correct wearing, proper lens care, plus regular follow up and immediate actions when eye health problems occur, it is safe to wear orthok lenses.
Orthok is a kind of rigid contact lens specially made with high oxygen permeability materials. Through the specially designed lens curvatures, it can gradually but not permanently change the curvature of the cornea under the mode of wearing at night during sleep, thus correcting the refractive error, mainly myopia (short-sightedness).
PolyU’s research study found that children wearing orthok lenses reduced their eyeball elongation by half compared to wearing regular eyeglasses, indicating that the rate of myopia progression retarded by half too. Due to the fact that the increase of myopia is more common in children, many parents may choose orthok to reduce the progression of myopia for their children. Many people mistakenly think that this kind of lens is only suitable for children. In fact, myopic adults can also choose to wear orthok lenses during sleep in order to enjoy clear vision without the need of wearing glasses or contact lenses during the day. Orthok is therefore specially suitable for people who love sports or those who are not easy to wear glasses and contact lenses during the day. Orthok is a non-surgical method of vision correction other than glasses. Orthok is suitable for children and adults, as long as they have undergone detailed examination and evaluation by the optometrists, and strictly followed the instructions and attended regular follow up.
We always hear some elderlies say that they see things blurry. Does it mean that we would have decreased vision when we get older? Is the blurry vision normal?
If you find that you get tired easily or have blurry vision during reading, it is possible that you get presbyopia. Presbyopia is a normal condition when people get older. It often starts from forty years old. No matter you are myopic or hyperopic, you would finally have presbyopia. As long as you seek help from optometrist and fit a proper spectacle, the vision could be improved.
If you have difficulty with your distant vision, it could be caused by multiple reasons. Besides myopia, hyperopia and astigmatism, cataract or age-related macular degeneration (AMD) could also be the cause. Cataract is more common, and the majority of people older than sixty would have it, and it get worse with aging. The symptoms of cataract is not obvious at early stage, and the vision is not much affected, so no treatment is needed for early cataract. Whether cataract extraction is needed depends on the severity of the disease and the vision requirement of the patient. Thus, not every patient with cataract have to do the surgery.
You might have heard of AMD, so what is macula? Macular is located at the center of retina, and it is the place where the photoreceptors are most densely packed. Healthy macula gives us clear and sharp vision. If macula become degenerated, we would have decreased vision or see things distorted, and we could have difficulty with our daily activities such as reading, watching TV and driving. Since the symptoms of AMD are not obvious at early stage, many people think that AMD is a normal condition of degeneration and the treatment might be delayed. However, once the cells at macular region get injured, vision could be preminantly decreased. Thus, early diagnose and treatment are important to keep our eyes healthy. Besides aging, smoking and long-term exposure to sunlight are also important factors aggregate AMD.
In fact, many eye disease are closely related with aging, so please get alerted when you see things blurry. We should check our eye completely and annually at optometrist, and find out the true reason for the blur. With annual eye check, not only could we imporve our vision, but also we could have better outcome for the following treatment.
Many elderlies regard blurry vision as a normal condition. Actually, as long as elderlies get familiar with soma eye-care tips, they could also have healthy eyes.
The most important thing to care for our eyes is to consult optometrist for comprehensive eye exam regularly. For long, many people think that eye check is only about cheking refraction. Actually, besides checking refraction, a comprehensive eye exam also include checking health of the eye. After the eye exam, not only eye diseases like cataract, glaucoma and age-related macular degeneration could be diagnosed, but also retina diseases induced by hypertension or diabetes could be detected. As a result, annual eye exam is very important for elderlies.
Besides regular eye check, eye care in our daily life is also very important. For example, elderlies should remember to wear proper sunglasses when going outside. A pair of proper sunglasses must have correct prescription to make the wearer see clearly, and should have good anti-UV function to protect the eyes from UV insult.
In addition, elderlies could use Asmler’s Chart to self-check if there’s macular degeneration. If the lines in the chart get blurry, distorted or even lost, a comprehensive eye exam should be conducted as soon as possible in order to have treatment in time.
Actually, health of the eye is closely related to the body’s health, good living habit could reduce the influence of systemic diseases to the eye. For example, stable blood pressure and blood glucose level are important to keep the eye healthy. As long as the elderlies take care of the eye, clear vision would be with you. Let’s start protecting our eyes from today!
Reading difficulty (or presbyopia) and white hair sneak in with increasing life experiences, and some people may feel a little annoyed by this in their early 40s. White hair can be dyed black, but how to solve the problem of presbyopia?
With the help of the latest manufacturing technology, progressive addition lenses (PAL) enable users to view at far distance and read at near clearly without the need to switch eyeglasses. PAL is a corrective lens that has multiple, line-free focal points or powers in a single lens. The distant vision is corrected when he/she looks straight with PAL. He/she needs to look down to use the lower portion of PAL for reading.
Before prescribing PAL, you must first understand your needs and working environment. People with different occupations and lifestyles have different visual needs, such as reading books or documents, computers work or playing Mahjong. Different types or brands of PALs could serve different purposes.
In addition, most of the Hong Kong people have prolonged use of computers, mobile devices and reading, thus they have a greater demand in intermediate and near vision. The optical zone for intermediate distance in conventional PALs is relatively smaller, compared to the ordinary reading glasses. Users may find difficulty in reading for a long time. Therefore, one might consider to prescribe a modified PAL that particularly for intermediate and near vision (so called office PAL). Office PALs have a larger optical zone for computer work and near task by shifting the optical zones for intermediate and near distance up.
In order to wear PALs comfortably, you must first understand the principle of PALs. There are different functions in different regions of PALs. To view the distant scene clearly, the wearer must look straight ahead while facing the target. On the other hand, your head can be tilted slightly forward with your eyes looking down when reading or looking at a near object with PALs.
The wearer might experience some discomfort or distortion if they look into the sides of lenses as the refractive powers on the peripheral part of the lens change gradually change. Therefore, it is advisable to turn their heads in order to view the peripheral objects.
To conclude, you should consult your optometrist before prescribing PALs. Don’t forget to adjust the frame frequently after prescription as your vision could be affected if the position of frame is not well fitted.
Presbyopia is not an eye disease, and it cannot be prevented. It is a normal loss of near focusing ability that occurs with age. Most people begin to notice the effects of presbyopia sometime after age 40, and it will gradually increase with age. Presbyopia is caused by the gradual loss of elasticity of the crystalline lens in our eyes and the weakening of eye muscles, which make it difficult for us to focus on close-up objects. Early symptoms include eye fatigue or headache after reading, feeling uncertain in focus while reading or using a computer/mobile phone, the need to pull near objects further away when reading, the need to take off myopia glasses to read, and having better reading ability in a bright environment.
Common Misunderstandings (1) – I won’t have presbyopia if I have short-sightedness (myopia)?
In people with myopia, the crystalline lens will also harden with age, and the accommodation will weaken, so there will still be presbyopia. The spectacle lens that is used to correct myopia is called a concave lens, where the effect is the opposite of reading glasses (convex lens). So, when a myope takes off glasses when looking at near objects, the effect is similar to wearing a pair of reading glasses. For instance, a person with 2 diopters of myopia needs to wear -2.00 D lenses to correct distant vision. If his presbyopia happens to be 2 diopters (+2.00 D), he needs to wear (-2.00 D) + (+2.00 D) = 0.0 D when looking at near objects (plano lens). Others may seem to think that they can read without wearing reading glasses. In fact, their myopia and presbyopia exist at the same time.
Common Misunderstandings (2) - Will myopia decrease due to presbyopia?
Myopia will not be reduced by presbyopia. For example, a person with 4 diopters of myopia needs to wear -4.00 D lenses to correct distant vision. If his presbyopia is 2 diopters (+2.00D), he needs to wear (-4.00 D) + (+2.00 D) = -2.0 D (2 diopters of myopia) for near. It can be seen that the myopic power for distance has not decreased, but when you look close, the presbyopic power offset part of the myopic power.
Common Misunderstandings (3) – Is far-sightedness (hyperopia) equal to presbyopia?
Hyperopia does not equal to presbyopia, the two have different causes. The cause of hyperopia is that the eyeball is too short, and the image of an object is focused behind the eyeball. The eye needs extra effort to adjust the image to focus on the retina. The cause of presbyopia is due to the loss of elasticity of the crystalline lens. For example, a person with 4 diopters of hyperopia needs to wear +4.00 D lenses to correct distant vision. If his presbyopia is 2 diopters (+2.00D), he needs to wear (+4.00 D)+ (+2.00 D) = +6.0 D (6 diopters of hyperopia) for near.
Common Misunderstandings (4) – Are over-the-counter reading glasses suitable for everyone?
Ready-made reading glasses may not be suitable for everyone. Few people have exactly the same refractive power in both eyes. However, the power of these ready-made reading glasses is usually the same on both sides, and there is no astigmatic correction in these glasses. If the image clarity for both eyes is unbalanced, the wearer may experience fatigue easily. In addition, the optical center distance of ready-made readers may not match the wearer's pupillary distance, and lenses with poor optical quality are prone to induce dizziness in wearers. More importantly, some people who experience blurred vision may casually buy ready-made readers to improve vision. As these lenses usually have a magnifying effect, they seem to improve vision a little. However, other causes of blurred vision such as cataract and macular diseases are not ruled out. Hence, it is highly recommended to have a thorough eye examination in case there is any vision problem.
Common Misunderstandings (5) – After wearing reading glasses, will my eyes deteriorate faster?
Wearing reading glasses does not affect the speed of presbyopia progression. Wearing appropriate reading spectacles in a timely manner can help reduce eye fatigue.
Will presbyopia continue to progress?
Your presbyopic power mainly depends on your reading distance and the fineness of your near work. For example, are you reading a book at 40 cm or using a desktop computer at 60 cm? Do you need to read small prints on medication bottles or small numbers on a printed spreadsheet? In general, when the presbyopic power reaches +2.50 D to +3.00 D, it will gradually stabilize. Overuse of the eyes, such as using computers, mobile phones and reading documents for a long time, reading in low light, as well as lack of rest will all contribute to the progression of presbyopia.
Presbyopia management options -glasses
Seek for professional help from an optometrist to prescribe a pair of glasses will help to solve the problem.
Single vision lens (reading glasses)
Advantages: the whole lens is for near vision, easy to adapt
Disadvantages: It is often inconvenient to frequently change the glasses for far and near
Advantages: It has two lens powers so that you can see both near and far. The top portion of the lens is used for distance, while the bottom portion is used for seeing up close. It is easy to distinguish and find the positions for far or near vision.
Disadvantages: 1. The dividing line for far and near is very obvious, making the appearance not attractive
2. If the prescriptions of the right and left eyes differ a lot, you may experience ghosting or double vision
3. There is a lack of intermediate vision. People with higher presbyopic powers may have more difficulties when looking at objects in the intermediate distance e.g. computers
Advantages: 1. No obvious dividing line on the lens, more attractive looking
2. It gives a wider zone of clear vision, one does not need to frequently change the glasses for far and near
Disadvantages: 1. More difficult to adapt
2. If the prescriptions of the right and left eyes differ a lot, you may experience ghosting or double vision
3. Higher expense
Presbyopia management options -contact lenses
The visual system can suppress a central blurred image in one eye. With monovision, the dominant eye is corrected for far while the non-dominant eye is corrected for near.
Limitations: There is a lack of intermediate vision and the depth perception (stereopsis) will be compromised
Bifocal contact lens
With a segmented bifocal contact lens, the near vision prescription is in the lower part of the lens, and the distance prescription is in the upper part of the lens. When you look straight, you will be using the far part. When you look down, the lens is held up by the lower eyelid and you will be using the near part.
Limitations: There is a lack of intermediate vision, the movement of the lens may reduce comfort
Multifocal contact lens
Multifocal contact lenses are designed with a gradual transition between near and far They are similar to progressive eyeglasses. It can be with concentric or aspherical design.
Limitations: Pupil size affects the visual performance, may be difficult to adapt, accompanied by glare or hazy vision
Presbyopia management options - surgery
Either with monovision, having a small amount of myopia left in both eyes, or to create a multi-focus cornea in the non-dominant eye
Limitations: Irreversible, need to carefully consider the risks and side effects, may still need to wear presbyopic eyeglasses after surgery
Intraocular lens (IOL) implant surgery
Multifocal IOLs, accommodative IOLs or extended depth of focus IOLs
Limitations: IOL implantation surgery without cataracts (clear lens exchange) requires careful consideration of the surgical risks and side effects
Corneal inlay refers to a tiny device being implanted into the cornea of the non-dominant eye to improve near vision. There are two main types of corneal inlays, namely refractive corneal inlays and small aperture inlays. The design of refractive corneal inlays is similar to a multifocal contact lens, with different areas of the inlay giving different levels of magnifying power. This allows the eye to focus up close and far away. Small aperture inlays work like the aperture of a camera, changing how much light enters the eye. It increases the depth of focus and provides better sight at close range.
Limitations: Effectively improve near vision, but contrast sensitivity may decrease, risks of glare, halos and difficulty seeing at night or reading in dim light.
The prevalence of myopia is high in Hong Kong and there is up to 70% of teenagers having myopia. The factors of myopia can be divided into genetic and environmental. Genetic factor is revealed by the fact that children with myopic parents have greater risk of myopia. On the other hand, the rate of myopia is higher in this new generation than the old one. It may be associated with environmental factors, including lack of daytime outdoor activities and prolonged near work. The eyes have to adapt the excessive near work and develop myopia.
In myopic eyes, the images of far objects are focused in front of the retina and become blurry. This makes people with myopia cannot see clearly at far but at close distance. When the myopia increases, the eyeball becomes longer. The retina is stretched to be thin and retinal breaks or degeneration may be resulted. This can cause vision deterioration and even blindness. As there is a trend of increasing amount of myopia in children in Hong Kong, it is expected that the risk of myopic complications in the population will be greater in the future.
In order to understand the cause, epidemiology and treatment of myopia, a lot of resources is spent on the myopic research worldwide. The Centre for Myopia Research, The Hong Kong Polytechnic University has undergone a number of study and has successfully invented myopia control products to retard myopia progression in recent years. It is hoped that this can reduce the influence of myopia on the society.
Glaucoma is an eye disease that the imbalanced high internal eye pressure induces the degeneration of optic nerve, the constriction of visual field and even blindness. Some research reported that the risk of glaucoma increased with the amount of myopia (shortsightedness). People with moderate myopia and high myopia respectively had 2.2-times and 4.6-times higher risk of glaucoma than those without myopia. It is uncertain about how myopia inducing glaucoma, but the optic nerve may be more vulnerable when it is stretched by the elongated eyeball in myopia. Moreover, the internal eye pressure is higher in people with myopia than those without myopia so that myopic people have greater risk of glaucoma.
Glaucoma can be classified as chronic and acute. Patients with chronic glaucoma usually do not have symptoms initially. Treatment is delayed if they seek medical advice until they discover central vision being affected. If chronic glaucoma is not diagnosed and treated on time, patients will lose their vision unconsciously and even become blind. For the acute glaucoma, patients usually have symptoms of eye pain, eye redness, headache and vision drop. The discomfort makes them seeking eye exam at once and then they can have treatment on time. In order to have early detection of glaucoma, people with high myopia should consult optometrists for eye exam and glaucoma evaluation, including assessments of eye pressure, visual field and retinal nerve fibre thickness.
High myopia (short-sightedness) is defined as myopia degree equals to or is greater than six dipoters. In the research of the School of Optometry, The Hong Kong Polytechnic University in 2012, the prevalence of myopia and high myopia in Hong Kong schoolchildren aged 12 was 61.5% and 3.8% respectively. This reflects the problem of myopia in Hong Kong is serious. How does high myopia affect the eyes?
When the myopia is higher, the eyeball is longer. The tissues inside the eyes are stretched when the eyeball elongates and this can induce degeneration and complications. For example, the related degeneration of vitreous and retina can cause retinal breaks and detachment in which symptoms include seeing floaters and flashes. The complications of macular neovascularization, haemorrhages and degeneration can result in blurry and distorted vision. In addition, the prevalence of glaucoma and cataract is greater in high myopia. The risk of these complications is increased with the age and the degree of myopia. Hence, high myopia is regarded as not only the refractive problem, but also the risk factor for the vision-threatening complications.
People of high myopia are suggested to have annual regular eye exam by the optometrists in order to detect any complications as soon as possible. If the symptoms increase or complications occur, more frequent follow-up is needed to monitor the conditions and treatment is required when necessary.
Crying is a tool for many people to express their unhappiness, but it is quite embarrassing and easily mistaken for being unhappy if their eyes suddenly become watery in public places without reason.
There are four main reasons for having watery eye. First, the eyes are stimulated by external sources, such as sand and dust or chemicals, and tear secretion will then increase. Second, patients have dry eye problem caused by insufficient tear volume or poor tear quality. Dry stimulation will make the eyes to secrete more tears but these tears cannot stay on the surface of the eyes to moisturize the eyes. Thus, those tears will soon flow out and cause tearing. Third, there is obstruction of tear ducts and tears cannot be drained away effectively. So, those excessive tears will flow out of the eyes. Fourth, the lower eyelids are loose and everted so they cannot support the tears and then cause tears flowing out.
To solve the problem, we must know the reason why we keep crying first. If the eyes are irritated, we consider to use artificial tears which can keep the eyes moist and wash away the irritants. At the same time, you need to prevent from the irritants source. If it is related to dry eye problem, you can also use artificial tears to moisturize your eyes. Patients with severe dry eye can also choose to use punctal plug to slow down and reduce the amount of tears that drain out so as to allow more water remaining in the eyes. If the tear duct is occluded, you can consider to have lacrimal dilation and irrigation for enhancing tears drainage. Although the lacrimal duct may have a chance to be occluded again, the situation of tearing will generally be greatly improved as long as the procedures can be done regularly. Finally, tears flowing out due to everting lower eyelid relies on surgery to change the structure of the lower eyelid so that it can support the tears secreted by the eye again.
If you experience similar situation, hurry to an optometrist to check your eyes and find out the reasons behind. Treat the symptoms and say goodbye to watery eyes!
Dry eye is a very common eye problem especially in middle-aged women and contact lens wearers. In most cases, it cannot be cured completely. Prescribing artificial tears is the most frequent management for relieving symptoms and dryness.
Some people may think that using artificial tears will reduce tear secretion. It is because some of the artificial tears containing preservatives such as Thimerosal and Chlorohexadine. The toxicity of the preservatives will affect the cornea and eventually causing some damages in long term. Initially, patients might not experience any discomfort during use due to the moisturizing nature of artificial tears. However, once stopped, those side effects from preservatives will come up. The discomfort feeling may even stronger than before and that is why some people mistakenly thought that the tear secretion was reduced by the use of artificial tears.
Recently, many pharmaceutical companies have launched unit-dose artificial tears without preservatives. There are also bottled artificial tears that use decomposable preservatives. Thus, the chance of having side effects are greatly reduced.
When feeling eye discomfort, the most common approach for patients is buying eye drops in the pharmacy. However, there are a variety of products available on the market.
How do we select the most appropriate eye-drops? What is your first consideration when choosing eye drops? Is it packaging? price? Friends’ recommendation? Or ingredients? If your answer is the former, you should spend a few minutes reading the following.
Artificial tears are mainly divided into two types: unit-dose and bottle-type. The former one does not contain preservatives. It would not cause any side effects or toxic reactions so it can be used multiple times a day. Most of the bottle-type artificial tears contain preservatives, which is not recommended to use more than four times a day. Some new formulas using decomposable preservatives, which can break down into mild substances under light, have lower chance of having side effects. Moreover, some bottle eyedrops consist of a special designed bottle opening, which has a filter preventing from bacteria. There is no need to add preservatives and can be used multiple times a day.
In fact, different lubricants target on different dry eye problems. Some of them focus on moisturizing cornea, some can increase the viscosity and stability of the tear layer, and reduce the friction between the eyelid and cornea; some oily-based eyedrops can slow the evaporation of tears; and some contain repairing ingredients that damaged cornea accelerates healing.
Most importantly, it is better to consult your optometrists or ophthalmologists before using eyedrops. Incorrect use of eye-drops may cause serious consequences. For example, some eye drops labelled to solve red eyes contain ingredients that can narrow the blood vessels. Although the redness reduces immediately after use, this is just temporary and the cause of the redness could not find out. In fact, there are many reasons of getting red eyes, ranging from dryness, conjunctivitis, keratitis to acute glaucoma. The treatment and management can be very different depending on each case. Dealing with the symptoms only may delay the time getting suitable treatment.
In addition, the use of inappropriate eye drops, including contact lens drops, can damage or inflame the conjunctiva; some eye drops containing steroids, such as excessive or long-term use, can cause glaucoma or cataracts and other eye diseases. In severe cases, it may even cause vision. Permanently damaged. Therefore, if you have any questions when purchasing or using eye drops, you can check with your optometrist. Do not use eye drops!
Eye dryness is one of the more commonly troubled eye problems among the elderly, and it is closely related to age. According to a study, more than 30% of Chinese aged over 65 have different degrees of dry eye, so the situation is quite common.
People with dry eyes often feel red, burning, foreign body sensation or itchy eyes. If not treated, it may cause corneal damage or inflammation. If scarring or ulcers occur, it can seriously affect vision.
There is no conclusive result about the causes of eye dryness so far. However, experts generally believe it may be due to problems with the immune system or tears quality changes with age. Earlier studies have found that tears from elderly contain only half as many antioxidants as younger people, while the antioxidants in tears can help to form a natural protective layer that protects the cornea. Eating more foods with antioxidants can also enhance the antioxidant protective layer in the tears and prevent dry eye disease.
People who use computers regularly or live in air-polluted environments are also more prone to dry eye. Artificial tears alone may not be effective in solving the problem of dry eye disease.
“Floaters” in chinese is “flying mosquitos” that vividly describes how annoying the floaters are. Those floaters are moving to and fro in front of your eyes, cannot be touched or caught; especially against bright background; whenever yours eyes are moving.
In fact, floater itself is not a disease, it is only a symptom. Age-related degeneration of our vitreous humor (jelly-like substance) and high myopia are the most common causes of floaters. Vitreous liquefaction and calcification lead to shrinkage and cloudy of the vitreous body. The floaters can be presented as dots, squiggly lines, threadlike strands, cobwebs or rings. The floaters can be in black, gray color, or semi-transparent. The present of floaters is persistent. We can get rid of them by simply taking any drugs.
In general, floaters do not cause any harm to our eyes. However, a sudden increase in number of floaters can be a symptom of retinal tear, hole or detachment. And this is particularly common in high myopes. A large amount of detached fibers or tissues cast shadows on the retina and cause sudden increase in floaters. If you encounter a sudden increase in floaters accompanied with flashes, or even blur vision, distortion and visual field defects, you’d better consult your optometrist or ophthalmologist immediately for a complete fundus examination.
About 10% of adults in Hong Kong have diabetes. Diabetic retinopathy is a complication of diabetes. Early diabetic retinopathy will not cause obvious blurring or pain to the eyes. When the disease progresses to the later stage, the vision will be obviously affected, and in severe cases, it may even cause blindness. Diabetes is one of the ten causes of blindness in the world. Apart from diagnosing retinopathy, regular eye examination is an effective method for evaluating diabetes control. The risk factors of diabetic retinopathy include older age, have a longer period of diabetes, have high serum cholesterol and rely on insulin therapy. The effects of diabetes on the eyes are mainly unstable vision, untable prescription of glasses, retinopathy, diabetic macular edema, cataracts, and glaucoma.
The prevalence of diabetic retinopathy is related to the duration of diabetes. Most patients having diabetes over ten years may have some signs of retinopathy. Diabetes can damage retinal vessels, affecting the absorption of nutrients by the retina. Proteins or blood could be leaked due to broken blood vessel walls, this will gradually affect visual function. If it is not discovered timely, long-term microvascular leakage will cause retinal hypoxia, growth of new vessels and serious retinal complications, such as macular edema, retinal detachment, vitreous hemorrhage, and fibrosis. Visual function will eventually be affected or even blind. In addition to retinopathy, diabetes may also cause cataracts and glaucoma due to vessel growth at iris. Since there are no obvious symptoms in early diabetic retinopathy, effective control of blood glucose level and blood pressure, regular comprehensive eye examination by optometrist or ophthalmologist can detect and control the disease early to protect the health of the eyes.
Macula (i.e. yellow spot) is an essential portion of the retina, consists of the highest density of photoreceptors, responsibles for providing clear central vision and color vision. Age-related macular degeneration (AMD) and myopic maculopathy are two main types of macular degeneration which may affect our central vision.
The estimated global population with AMD is 196 million in 2020, increasing to 288 million in 2040 (113 million in Asia). The prevalence of AMD in Asia is around 7.4%. AMD is the leading cause of severe vision loss (~6%) or even blindness (~4%).
Risk factors for AMD include aged 50 or over, family history of AMD, sunlight exposure without UV protection, cardiovascular disease, hypertension, high cholesterol levels, smoking, low dietary intake of antioxidants, etc.
It can be further classified into two types: dry (atrophic) AMD (~90%) and wet (exudative) AMD (~10%). Dry AMD is characterized by pigmentary changes, drusen and atrophic areas, while wet AMD is characterized by abnormal growth of new vessels.
Symptoms of AMD include distorted and wavy shapes, gradually reduced vision and complete loss of central vision or even blindness.
There is no specific therapeutic or surgical treatment for dry AMD. Healthy lifestyle, smoking cessation (avoid secondhand smoking), increase dietary intake of antioxidants (especially lutein and zeaxanthin) may prevent the AMD development or slow down the progression to wet AMD. According to AREDS and AREDS2 studies, the National Eye Institute of the USA suggested that taking AREDS/AREDS2 supplement formulation (with high doses of lutein, zeaxanthin, zinc, vitamin C & E) may reduce the risk of AMD progression and its vision loss in intermediate/ advanced stages. Early detection of wet AMD and implementation of anti- vascular endothelial growth factor (anti- VEGF) injection is important to prevent further vision loss. However, the vision loss caused by AMD is irreversible. Low vision devices may help clients to maximize existing vision to improve their quality of life.
Myopic maculopathy usually happens in patients with more than -6 diopters and/or with eyeball length >26mm. The elongation of the eyeball results in thinning of the retina, choroid and sclera. The choroidal thinning may lead to reduced blood supply to the retina and hence causing retinal and macular degeneration. Myopic maculopathy may also accompany with epiretinal membrane, foveoschisis, macular hole, choroidal neovascularization etc. Symptoms of myopic maculopathy are similar as those in age-related macular degeneration, including distorted and wavy shapes, gradually reduced vision and complete loss of central vision or even blindness. The risk of myopic maculopathy increases with the degrees of myopia, the length of the eyeball and age. Regular eye examination is important to detect myopic maculopathy.
According to the latest figures from the World Health Organisation, glaucoma is the second-leading cause for blindness in the world, which took away eyesight from approximately 2% of the global population. Glaucoma is a serious eye disease, which damages the nerve on the retina, creating irreversible vision and visual field loss (visual field means how wide is being seen when the eye is not moving). Glaucoma patients would have a narrowing visual field, which would end up in tunnel vision, and eventually blindness.
There are ACUTE and CHRONIC subtypes of glaucoma. Acute glaucoma is due to the rapid increase of eye pressure, causing headache, eye pain, nausea, and seeing halos. These symptoms can hardly be missed. In contrast, chronic glaucoma can be asymptomatic, especially in the early stage only the peripheral visual field is damaged. When the narrowing of visual field is subjectively noticed, the condition could have been worsened to intermediate, or even advance stage. Even in developed countries, more than a half glaucoma paitents did not know they had the disease before an eye check, according to a research study.
To date, the cause of glaucoma is still controversial. Unfortunately, despite plenty of work that had been done, glaucoma still remains incurable. Currently, glaucoma patients could reduce the eye pressure by means of medications or surgical interventions to control the rate of deterioration. The latest research studies are aiming at developing medications and supplements to protect the nerve on the retina, i.e. neuroprotection.
To protect the vision from the “stealthy” glaucoma, regular eye check items, including vision, eye pressure, retinal health, and visual field assessment, could provide invaluable information to optometrists to discover and treat glaucoma at an early stage. For high risk populations, including high myopes, familay history of glaucoma, elderlies, diabetes, and hypertension, regular eye check is more crucial to rule out the opportunity of having glaucoma. In recent years, the School of Optometry in HKPU has been working to effectively diagnose glaucoma at an earlier stage, hoping these patients could get proper treatment as soon as possible.
Cataract refers to the condition that the crystalline lens inside the eyes become opacified and cause reduced vision. Is it possible to prevent cataract from happening? Can we slow down the progression of cataract? Actually we can.
To avoiding getting cataract, we can wear sunglasses with UV protection when walking outside. Too much UV-light absorption will lead to accelerated degeneration of the crystalline lens, and makes you get cataract at a youner age.
Once there was a patient who already get moderate degree of cataract at an age of 40. This is because he needed to work outside long term and used to hiking on holidays, without the habit of wearing sunglassess or sunhat. It might be the excessive exposure to sunlight that makes him get cataract earlier than others.
Other prevention measures include taking more green vegetables that are rich of antioxidants and avoiding smoking. Diabetic patients need to control their blood glucose because unstable blood glucose level will accelerate the progression of cataract. Since many patients may not be able to aware of their problems at an early stage, we suggest people to have regular comprehensive primary eye examinations to find out their ocular health conditions.
Practice makes perfect, it is important to have sufficient practice for good sports performance. However, good visual function is also essential for sports players.
Vision is not only seeing clearly, many precise visual skills can also affect the performance in sports. According to researches, many elite athletes have excellent visual functions. For example, in playing ball games, athletes must have excellent eyesight, peripheral vision, stereo vision and eye-hand coordination etc., so as to sharpen their reaction and judgment skills during the games.
Athlete who has refractive errors needs to have vision correction either by wearing a pair of spectacles or contact lenses. Vigorous sports, such as football and basketball, have a greater chance of colliding with each other, wearing soft contact lenses may be more appropriate. The benefits of contact lens wearing are : 1) reduction of the chance of broken lenses caused by collision, which can damage the eyes and; 2) prevention of blockage of peripheral vision by the spectacles frame. If the eyes are not suitable for wearing soft contact lenses, some impact resistant plastic frames and non-fragile polycarbonate lenses can also be used during vigorous sports, and the spectacles can be tightened by eye glasses straps too.
Sports injury is another important topic in sports vision. Once the eyes get injured, the damage can be very serious and permanent vision loss is possible. To avoid these accidents, you must wear appropriate eye protector during ball games. Water sports such as windsurfing and water skiing, owing to the reflective property of the water surface, the chance of ocular exposure to ultraviolet rays is highly increased. Prolonged exposure to ultraviolet rays will increase the chance of eye disease such as cataract. Therefore, when performing water sports, you must wear a UV protection glasses.
Consult your optometrists for assessing your visual functions for your sports and if needed, visual training for sports vision can improve your visual skills as well. Don’t forget to consult your optometrists on which visual correction or protection tools are suitable for you and your sports.
Do you find ‘sports vision’ a bit strange to understand? In fact, sports vision service is a unique professional eyecare service dedicated for professional athletes and sports lover. The Optometry Clinic’s Sports Vision Unit offers sports vision specialty services. Our experienced optometrists understand how your visual system work. We provide sports vision assessment and customized vision training programs to help athletes strengthening visual skills necessary for peak performance.
Our Sport Vision Service includes:
- Comprehensive eye examination: Identify visual problems such as refractive errors, binocular function and ocular health that may affect performance;
- Sport vision assessment: Analyse sports-related ocular functions, such as dynamic visual acuity, contrast sensitivity; peripheral awareness, eye-hand/body coordination, etc.;
- Sport vision training: Enhance visual skills through customised visual training.
Besides, sports-related eye injuries may cause permanent damage to vision. Injuries can be simple bruises to fractured eye sockets and retinal detachment. Our optometrists will give advices on appropriate protective eyewear as well as performance sports eyewear and contact lenses (UV/ transition contact lenses). Come and consult our optometrists about how to protect your eyes from sports injuries.
Eye injuries could happen during sports, especially ball games and sports with physical collision or contact.
Trauma caused by sports can cause permanent damage to the eyes, including bruises, irritation, severe bone rupture, retinal detachment, and blindness. In addition, prolong outdoor sports with extensive exposure to the ultraviolet rays may cause cataracts, pterygium, corneal burns, and anterior uveitis.
The material of protective goggles is impact-resistant polycarbonate, the advantages include non- fragile, light-weight and ultraviolet protection. Some people choose different colour filters to improve the contrast of objects for better performance. In addition, polarized lenses can also block dazzling reflection, making clearer and comfortable vision.
Different coating on the lenses will also help to protect our eyes. For example, the mirror-coated surface can further reduce the direct sunlight entering the eyes. It is especially important for outdoor sports such as skiing, beach volleyball, and cycling that are often exposed to sunlight. Goggles such as headbands or face masks require anti-fog coatings to prevent the accumulation of mist and block vision, and anti-scratch coatings can increase the durability of the lenses. For swimmers with high refractive errors, they can prescribe personalized swimming goggles with individualized prescription. The goggles can provide clear vision for the game and allow them to walk around the pool safely.
Consult your optometrists about which kinds of protective goggles would be suitable for you and protect your eye from sports injury.
The use of computer has become an unavoidable part of our daily life. However, electronic device is a double-edged sword－it can be amazingly convenient, but it gives rise to unfavourable consequences to our eyes. The most common ocular problems are eyestrain, redness, dryness, and a feeling of burning or stinging in the eyes. Among all computer users, people with accommodative insufficiency, pseudomyopia, and those with uncorrected refractive errors (myopia, hyperopia, astigmatism and presbyopia) are more susceptible to those problems.
According to a study conducted by The Hong Kong Polytechnic University regarding the relationship between reading and blinking frequency, people tend to blink less while reading. Prolonged reading may cause fatigue of eyes more easily. In fact, the impact of prolonged computer use is similar to reading. Decreased blinking frequency is one of the culprits of dryness and stinging feeling of eyes. And contact lens wearers are more prone to having these symptoms. Apart from trying to blink more, another solution, according to a different study carried out by the School of Optometry, is to adjust the position of the computer monitor lower, allowing the eyes to look down slightly, which can reduce the area of contact of the eyeball and the air, and hence alleviate the symptoms of dryness. Contact lens wearers can also use artificial tears to relieve the discomfort of eyes.
Another problem triggered by prolonged computer use is colour vision disorder, which is the confusion in colour sensation. The most common example is being unable to differentiate blue and yellow, or green and red. The smaller the text, the more difficult it is to distinguish the colour. The symptom could last for few minutes to few hours. The ways to prevent colour vision disorder include using black text on white, avoiding text and pictures with too much colour. Moreover, high monitor brightness, rapidly changing images on screen, and frequently flickering light could induce photosensitive epilepsy. Although the chance of having photosensitive epilepsy is very low, people suffering from this problem experience adverse symptoms, such as severe headache, nausea, and having a paled face. People should seek immediate medical care when having the above symptoms.
As we all know, prolonged computer use exerts burden on our eyes. Nevertheless, most office workers in Hong Kong need to use computer all day long. Here are 10 tips of eye protection which may help computer users to relieve eye strain, and use computer in a more healthy way.
- Sufficient lighting in the working environment, but dazzling light should be avoided
- Add some picture with tender color to sooth eye fatigue
- Add window curtains to avoid glare on screen caused by direct sunlight
- Use matt color for the furnishings surrounding the computer, such as wall, furnitures, keyboard, and other accessories on the table. Avoid using shiny color or metal
- Keep appropriate room temperature, and maintain indoor relative humidity at 50% to 70%
- Avoid looking at flickering images, to reduce the chance of headache or eye strain
- Use suitable screen brightness and contrast
- For LCD monitor, ensure reading angle, font size and spacing is adequate
- For people with refractive errors (such as short-sightedness, long-sightedness, astigmatism and presbyopia), especially those with astigmatism, a spectacle with correct power should be prescribed. People with presbyopia should use bifocal, progressive, or reading +glasses for computer use with appropriate power.
- For people with accommodative problems or pseudo myopia, please consult an optometrist for comprehensive eye examination, and vision training may be prescribed if needed
The above 10 tips may help to relieve eye discomfort when using computer. However, the crucial way to combat eye fatigue is to use computer in a controlled time and take regular break, so that the body and eyes can have sufficient rest. And do not forget to do comprehensive eye examination annually to check ocular health.
With the popularity of computer and advance of information technology, the use of computer and other electronic devices is no longer the privilege for adults. Nowadays, many primary and secondary school students, or even kindergarten kids utilize computer or online platform for learning and discussion. They may need to spend few hours a day sitting in front of a computer. Will prolonged computer use temporarily or permanently diminish children’s eyesight? Being parents, how can we minimize the damage of children vision caused by electronic devices?
It is common for children to feel eye strain and discomfort after long term computer use, like adults do. Other common symptoms include eye pain, blurry vision, dry eye, double vision, and so on. These symptoms are generally known as “Computer Vision Syndrome”.
Apart from the heavy homework loads, children also need to spend lots of time on computer work. Without enough rest, their eyes will be prone to dryness, weakened accommodative ability, or even blurriness. Besides, most computer desks and chairs are designed with the ergonomics of adults, which may not be suitable for children. They may need to lift up their heads to look at the computer screen. This incorrect posture may not even cause harm to eyes, but also induce pain in waist, lower back, and neck. Scientific studies showed that staring at a computer screen for a long time may lead to transient myopia. The influence of prolonged computer use upon myopia progression requires further studies.
In modern society, using electronic devices for learning has become an indispensable part of our lives. But how can we take precautionary measures to minimize its effect on children vision? Here are some suggestions for parents and teachers:
- Regular comprehensive eye examination for children is important for optometrist to check if there is any hidden problems, and correct them accordingly, such as prescribing spectacles, contact lenses, or vision training, if needed.
- Make sure there is sufficient lighting when using computer, while direct strong light towards eyes should be avoided. After 20 minutes of computer work, take a rest for at least 20 seconds to look at 20 feets away. Suitable font size, colour and contrast should be set to ensure easy and comfortable reading. And the screen should be set at a sufficient distance from the eyes (at least 20 inches).
- Tables and chairs with adjustable height should be chosen for children.
Glare can grossly be divided into two categories: discomfort and disability glare. It is a vision impairment produced from the direct or reflected intense light that spread over an area of the visual field. The visual disturbance is usually more severe when the glare is close to the line of sight. Within the central 45 degrees of the visual field, glare often causes discomfort, light-sensitive, and blurred vision.
The School of Optometry of the Hong Kong Polytechnic University has recently interviewed 420 experienced drivers who obtained their driving license for an average of 23 years. About 80% of the drivers reported that glare, primarily caused by the sunlight in the daytime and oncoming headlight at night, interfered their driving performance. The most common symptoms were discomfort, itchy eye, tearing, dry eye, headache, blurred vision, and red eye. When drivers encountered these vision problems while driving, they found it difficult to concentrate on controlling vehicles and discerning the road environment, putting pedestrians in danger.
Because professional drivers usually work for a long hour, the risks arisen from glare are generally higher than that of ordinary drivers. Are there any solutions?
We recommend that the public should consult optometrists regularly and wear UV-blocking sunglasses during the day. Clip-on or fit-over sunglasses are particularly suitable for drivers who require to use the tunnel frequently. At night, drivers should not wear sunglasses and avoid looking directly at the oncoming headlights. Whenever the eyes feel uncomfortable, you should avoid driving and park the vehicle in a safe environment, allowing your eyes to rest for a few minutes.