Myopia Profile

Clinical

The SightGlass DOT Lens - Q&A with Dr Sherman Tung

 Posted on November 28th 2022 by Dr Sherman Tung

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Our new Q&A format is designed to explore a particular clinical topic, intervention, product or research paper with an expert. Here, we talk to Canadian Optometrist Dr Sherman Tung about his experience using the new SightGlass Vision DOT (Diffusion Optics Technology) 0.2 spectacle lenses in his practice for myopia management.

Q&A with David Kern (1920 × 1500 px) (1).png How do you decide which treatment to prescribe in myopia management?Q&A with Dr Sherman Tung (1).png My decision is based on collective data which includes the child’s age, refractive error/axial length, parental history, ethnicity, and lifestyle (interest/activities). The appropriate treatment will be based on what is commercially available in Canada, the benefits, and risks of the treatment for the child. For young children, I am comfortable prescribing myopia control spectacles because of its minimal safety risk and the spectacles correct and potentially control the myopia control. So, it is simple and easy to explain to parents.Q&A with David Kern (1920 × 1500 px) (1).png How do the SightGlass DOT lens fit into your practice?Q&A with Dr Sherman Tung (1).png SightGlass DOT lens is commercially available in Canada so we can offer this to our patients. This is another option we have available in our toolbox along with myopia control contact lenses or therapeutic eyedrops. If the child or parents are not interested to start with contact lenses or eyedrops, then DOT lenses are an option. This is also useful for those needing astigmatic correction.

SightGlass Vision DOT 0.2 lenses have been investigated in a randomized clinical trial of children aged 6 to less than 10 years, with interim 12-month data recently published. The results showed that children wearing the test lens had 0.15mm axial length growth in a year, compared to 0.30mm in the control group, representing a 50% reduction. For children aged 6-7 years, refractive progression was -0.19D in a year in the test lens compared to -0.75D in the control group.1

This age group tends to show some of the fastest myopia progression,2,3 and this is the first data set available on effective myopia control spectacle lenses for these younger children.

Q&A with David Kern (1920 × 1500 px) (1).png Is there a particular approach that you find most useful in explaining the SightGlass DOT lens to parents and patients?Q&A with Dr Sherman Tung (1).png It is important to explain to parents that the child has myopia, that is why their vision is not clear to see at distance. This can be fixed with corrective lenses. However, it is known that the myopia may progress over time, meaning that the strength of the lens will increase and by the time your child is at high school or university, their prescription could be much more than what it is now. Even though we cannot exactly predict if your child’s myopia will progress fast, there are corrective lenses with additional feature that can help slow down the progression of myopia for example the SightGlass DOT lenses, which work by lowering contrast. This is achieved through the pattern you can see on the lenses. By softening the image received, it reduces the stimulus for eye growth. I usually put the spectacles on my face so the parents and the child can see the spectacles when worn. In addition, I always emphasize that in order for this to work, the child must wear the glasses.SGV-Sherman-Tung3.jpg

Dr Tung makes an important point here about wearing time. It has been shown in other spectacle and contact lens studies that increased wearing time leads to better myopia control results. In the CYPRESS study,1 recommended wearing time was an average of at least 10 hours per day, every day.

Around 20% of children removed their glasses for near vision activities, these primarily being reading and writing. The authors cited that removal of spectacles for reading could have had an influence on efficacy of the glasses. The International Myopia Institute Clinical Management Guidelines recommend that children wear their myopia correction and treatment full time.4

Q&A with David Kern (1920 × 1500 px) (1).png What have been your clinical findings in terms of vision and visual function?Q&A with Dr Sherman Tung (1).png In my practice, we measure visual acuities using Snellen high contrast chart. The SightGlass DOT lens binocular vision for distance and near visions are just like regular glasses. My patients will walk out of the practice with 20/20 vision. If you measure the lenses with a lensometer, if the prescription is -1.00DS, the lens will measure at -1.00DS. The lens power is uniform throughout, just like a clear single vision lenses. We also asked the child/patient to walk around the room, show them a book so they see the print. Yes, there is a slight reduction in contrast (instead of a black image, it will appear like a dark grey) but all the shapes are still intact and recognizable. Assuming they have normal visual acuities, their visual function is unlikely to be affected.

Diffusion Optics Technology (DOT) 0.2 lenses are designed to reduce contrast signalling in the retina to slow myopia progression, providing clear central vision with a slightly less contrast in the 'peripheral' component of the lens. The clear central portion is useful for fine detail and also aids the practitioner to measure the lens power. As Dr Tung describes, this does not appear to impact visual function or lifestyle in wearers.

You can read more about the design and research outcomes of the DOT lens in the recently published one year randomized controlled trial.1 More Myopia Profile resources and Science Summaries on this data are found via the links at the end of this article.

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The image above shows a child wearing the SightGlass Vision DOT 0.2 lenses, which are available in Canada and outside the US, showing the aesthetic appearance of the lens seen on the child's face.

 How do you determine a successful outcome with the SightGlass DOT lenses in myopic children, both short-term and long-term? I started using SightGlass DOT lenses in March 2022. Short-term, we have not had any issues that are different than what you will typically see with regular glasses. To date, I have not had an encounter where we must update the child’s prescription (typically 0.50D increase or more). In addition, most patients who are using DOT lenses have not had an axial length increase by more than 0.20mm. Therefore, I believe these lenses show great promise for myopia control. As an eyecare practitioner, it is our job to explain and educate parents about the importance of myopia management and present the options available. There is no downside to starting prevention early. Then we must let the parents decide what is best for their child. Long-term, only time will tell. Based on the published 12-month results, I am encouraged. Also I am aware that SightGlass completed a 3-year clinical study at 14 sites in North America and that they are continuing to follow up beyond 3-year. I hope we will see similar outcomes in our practice.

Whilst this technology is in its early stages, a 12-month interim analysis from this ongoing trial - Control of Myopia Using Peripheral Diffusion Lenses Efficacy and Safety Study (CYPRESS)1 has demonstrated the safety and efficacy of the DOT 0.2 spectacles for reducing myopic progression. The 3-year clinical trial has been completed and reported at the recent American Academy of Optometry meeting in San Diego. The extension study is ongoing to ultimately report on axial length and refractive control data beyond three years.5

Further reading

Important note: DOT lenses are currently not available in the US but are available in selected countries outside the US.

Meet the Authors:

About Dr Sherman Tung


Dr. Sherman Tung is based in Vancouver at Eyelab, which is a unique and creative OD practice specializing in Myopia Management and Vision Therapy.  His passion and dedication for myopia management led him to pursue a fellowship in both the FAAO and FIAOMC. He was honored to be named BC Optometrist of the Year in 2019, the highest award given to an optometrist who has not only contributed to the advancement of optometry, but has also demonstrated a fervent commitment to serving the community and improving the visual welfare of the public.


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