School of Optometry
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About us > Our Research > Healthy Lifelong Vision
Healthy Lifelong Vision
Ageing eye research is one of the two (with myopia) research foci of the School of Optometry. With the anticipated increase in our ageing population in Hong Kong, more people will suffer from age-related general health problems as well as eye diseases. Our goal is to find better way to manage for eye conditions, such as glaucoma, diabetic retinopathy or retinal degeneration and cataract, so as to preserve vision in our community and beyond.
Glaucoma is an ageing eye problem and it is the leading cause of irreversible blindness in the world. In particular, primary open angle glaucoma (POAG) affects 2% of people aged 40-50, and 8% of our elderly population (over 70) has increased eye pressure - a risk factor for glaucoma. The prevalence of glaucoma also increases with age. Clinically, glaucoma patients are managed by eye drops and/or surgical procedures which act to lower the intra-ocular pressure of the eye and prevent further visual loss. However, there is no cure in sight. The research team aims to characterize the pathology and find new solutions to glaucoma. We study the cellular mechanisms of aqueous humour formation and drainage. We are also interested in the retinal changes in glaucoma and neuroprotection. Clinically, our research focuses on the early diagnosis of glaucoma. Our glaucoma research is supported by the Niche Funding of the PolyU.
Mechanisms and Regulation of Aqueous Humor Formation
Several electrophysiologic techniques are being employed to study the mechanism of secretion across the ciliary epithelium. In particular, Ussing chamber is used to measure the transepithelial electrical response across the intact epithelium. Electrical parameters including transepithelial potential difference, short-circuit current and tissue resistance are continuously monitored. The patch clamp technique is used to investigate the ionic movement across the individual cell (whole cell recording) or individual channel (inside-out and outside-out patch). Other techniques are also used to investigate the regulation of aqueous humor secretion. For example, a special-designed chamber is used to directly measure fluid secretion across the isolated ciliary epithelium. We have also developed an arterially-perfused eye model to determine the rate of aqueous humor formation and intraocular pressure (IOP) in vitro. Fluorescence imaging technique is used to determine the intracellular signaling pathways within the ciliary epithelial cells.
Clinical Electrophysiology and the Ageing Eye
Clinical electrophysiology of vision is the study of the physiology of the visual system (retina, visual pathway and visual cortex) by measuring visually-evoked electrical signals. It measures small variations in nerve impulses that provide an objective functional assessment of the visual system. The visual electrophysiological technique is widely used in the assessment of the different ocular diseases or ocular-related systemic diseases, such as retinitis pigmentosa, cone/rod dystrophy, age-related maculopathy, optic nerve disorders, multiple sclerosis.
Low Vision and Vision Rehabilitation
“Low vision,” “visual impairment” or “impairment of vision” is when vision is reduced to an extent that it cannot be corrected with medicine, surgery, or a standard refractive correction. Low vision, significantly hinders the everyday functioning of an individual. In 2014, around 12% of Hong Kong elderly aged 65 years or above were visually impaired. Cataract, macular degeneration, myopic degeneration and glaucoma are common causes of low vision.
Clinically, optometrists can prescribe the use of appropriate low vision devices and adaptive technology instruments as well as offer different clinical and rehabilitative strategies to visually impaired patients to enhance their functional vision more efficiently and effectively.
Our goal of low vision rehabilitation is to enhance patients’ quality of life through maximizing the use of their remaining vision. Our research studies aim to examine the efficacy of different interventions such as visual perceptual learning and non-invasive brain stimulation to improve patients’ visual functions and daily life performance. Furthermore, our studies also aim to provide scientific evidence for establishing barrier-free and safe environments to enhance patients’ navigation and mobility performance.
Dry Eye Disorders
Dry eye is one of the most common age-related ocular problems. There are over 50 million dry eye sufferers in the USA and more than 30% of Chinese People over the age of 65 experience dry eye condition. Dry eye problems are also common in contact lens wearers. The prevalence of dry eye will increase with the ageing of the population and increased contact lens usage. However, the underlying causes have not been fully established. In dry eye disorders, the patient experiences ocular discomfort, with burning, itchy, sandy or gritty sensations. Left untreated, dry eye disorders can lead to scarring or ulceration of the cornea, and possible loss of vision. Therefore, treatment is important not only for improving comfort but also for improving the health of the cornea and maintenance of vision. The aim of our research is to investigate the mechanism of dry eye and to find effective methods for dry eye treatment.
Tear Physiology
Studying age-related changes in tear composition can help gain insight into dry eye disorders. We have been working in the area of tear fluid and corneal health for over 15 years. Various tear components have been investigated including tear protein, electrolytes and antioxidants. We have pioneered the use of well-established biomarkers of oxidant/antioxidant balance and the FRAP assay [US patented] to identify the antioxidant capacity of human tear fluids. Using FRAP and FRASC [a development of FRAP], we can investigate various aspects of tear antioxidants, including stability, variability, source, relationship with plasma levels and the effect of antioxidant supplementation.
[IMAGE: Tear Physiology]
Dry Eye Cellular Response
We have successfully developed a novel ex-vivo porcine dry eye model which can simulate the difference in severity of dry eye for testing ophthalmic solutions on corneal cells. The effects of various factors in ophthalmic preparation (in terms of osmolarity, pH and viscosity) on dry eye treatment have been identified.
[IMAGE: Cellular Response]
Research on the cytotoxic effects of dryness on the DNA of corneal epithelium is scarce. We use comet assay in the corneal epithelial cell to identify the amount of DNA strand-break. We have also developed a series of flow cytometry assays for use in a tears/corneal epithelial cell model.
[IMAGE: Cellular Response]
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