School of Optometry

Webinar on Myopic Defocus Technologies - FAQs

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1. What types of patients are suitable for wearing the DIMS lens, e.g. strabismus, esophoria, age (adults, teenage, young children), progressive or stable, low myopes (new diagnosis) or late onset and different ethnicity?

We only recruited 8-13 year-old HK Chinese children with no strabismus in our current study.

2. Can the DIMS lens be used in the prevention of myopia (e.g. in hyperopes or emmetropes)?

We only recruited myopic children in our current study, thus there is no evidence showing that DIMS lens could prevent myopia at this moment.

3. How is the visual performance of the lens?(e.g. does it affect contrast sensitivity, vision acuity, visual field, accommodation; can patients use it with sport?)

Our results showed that there were no significant differences in contrast sensitivity and accommodation between the subjects wearing DIMS lenses and single vision lenses. We did not collect data about peripheral vision.

Our subjects reported they could play sports as usual when wearing the DIMS lenses after the adaptation period, including ball games and cycling. However, we still suggest that wearers use the DIMS lens with sport only after an adaptation period, like when using PALs.

4. How does the DIMS lens compare with other myopia control methods (OrthoK, LAMP, MiSight, Atropine, light intensity/wavelength, outdoor activities) or combination therapy?

Four modalities are currently regarded to achieve a good level (50% or above) of myopia control: topical pharmaceutical agents, orthokeratology (~50-60% on average), soft bifocal contact lenses (~50%), defocus incorporated spectacle lenses (DIMS spectacle lens, 60%). Use of atropine (regular dosage 1%) is the most effective method in myopia control among the four modalities. The general treatment efficiency can achieve up to 70% or above. However, the side effects of atropine, such as sensitivity to light and near blur canhinder the clinical application of 1% atropine. Low-concentration atropine may be of clinical relevance as it shows promise in myopia control with minimal side effects.

5. Do we need to prescribe lenses with under-corrected myopia? Does the defocus of the micro-lenses vary across the lens? How was the defocus of+2.50/+3.50 chosen?

Up to the present, there has been no strong evidence showing that myopia progression can be slowed by under correction of myopia. Our clinical trial showed that the DISC lens with +2.5D defocus could slow myopia progression significantly.

6. How can the treatment effect be maximised? When can treatment be stopped? What type of follow-up is needed?

Having a good compliance of lens wear is important. We instructed the subjects to wear DIMS lenses all the time. We recommend that patients have regular follow up of refraction and VA every 6 months if possible and it is best to include axial length measurement as well.

7. How is the DIMS lens fitted and verified? What is the cost of the lens? Do we need adjustment to the refraction?

Lens fitting of the DIMS lens is similar to that of PALs, including frame selection, frame adjustment, measuring pupillary distance and fitting height, etc. The power for the distant correction could be verified using a focimeter in optometric practise. The multiple segments can be seen under the bright light but do not significantly affect the appearance of the lens. In the clinical trial, the prescription was based on the full cycloplegic subjective refraction. In clinical practice, the need for Rx adjustment should be up to the clinician’s professional decision.

8. Is the DIMS lens accessible for the UK?

Please contact HOYA Corporation for access information.

9. Would you please provide the details of the trial, including visual performance, unsuccessful cases, any regression of axial length?

We carried out several tests to examine visual performance with DIMS lens wear, e.g. distance VA, near VA, accommodation tests and stereopsis. There were no significant differences in those tests between DIMS and single vision lenses.

Similar to other methods of myopia control, the DIMS lens does not work for every myopic child. In the clinical trial, 21% of DIMS subjects showed no myopic progression.

10. Could there be other factors resulting in a slower myopia progression, e.g. lens shape, light?

We are working on the data analysis of more factors in the current 2-year study. Some studies in the literature have shown that lens shape, peripheral refraction, light intensity and spectrum and time spent on outdoor are correlated with myopic progression and changes in refraction.

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