By 2050 half of the world's population is going to be myopic What is myopia? Myopia is when someone needs to wear minus-numbered glasses to see clearly for far. There are three main causes of myopia apart from a few others
Myopia control has thus become a very important topic in the eye care world.
Apart from a few others, there are three main ways that you can control myopia today.
Whenever light enters the eye the rays of light meet on the Retina. If they meet on the Retina then we see clearly. In myopia, the problem is that when rays of light enter the eye they meet in front of the retina and therefore you see a blurred image
So as shown in the diagram if there are two rays of light and they meet on the retina which is the back part of the eye then you see a clear image. However, if these rays meet in front of the retina then you see a blurred image. And because of this blurred image, we cannot see clearly. And thus we have to wear spectacle lenses or minus numbered lenses. And what these minus numbered lenses do is that the rays of light move outwards and then they meet on the retina. Because of these minus number lenses, we are able to see things clearly
Unfortunately when we say clearly we are basically referring to only the central vision. We are not referring to peripheral vision.
Please refer to the diagram above. What happens normally is that when rays of light enter the eye they reach the retina. When we draw this diagram we only talk about two rays of light, but normally there are multiple rays of light and they all go towards the retina. And the way they hit the retina is shown in the diagram (Fig 2). And what this shows is that while the person is seeing very clear in the centre there is a defocus in the peripheral retina.
Defocus means these rays of light are actually meeting behind the retina. Now when they meet behind the retina the signal that the eye sends to the brain is that the eye is shorter than it should be. It serves as a stimulus for the eye to grow longer or myopia to increase. This peripheral defocus is called a hyperopic defocus. A hyperopic Defocus is when the rays of light meet behind the retina. These new glasses which are based on the DIMS technology basically cause the peripheral rays of light to focus in front of the retina. And they cause what is known as a myopic defocus.
The way that these lenses achieve that is they're not being like traditional lenses they basically have two zones to the lens. One is the central zone and one is a peripheral zone The central zone basically takes care of the central vision and the central zone is like any other spectacle lens that you have used in the past. The peripheral zone, on the other hand, has a honeycomb pattern. The honeycomb pattern has a plus number on some parts of the honeycomb, and what this plus number does is moves these rays to meet in front of the retina. Once these rays are moved here the stimulus for this eye to grow longer reduces.
Studies show that there is a chance of 60% of myopia not increasing when these lenses are worn. The company, Hoya, now have to follow up studies for up to three years. In fact, the company is so sure that the lenses work that If you start wearing these lenses and if your number increases by .75 Dipoters in the first six months they would actually replace the lenses for free with the new number.
These lenses were introduced in India in November of 2021 where there were used by some very big autonomic institutes. They were introduced in private practice in the month of Feb or March in 2022. Compared to regular spectacle lenses these are much more expensive. So as of May 2022 these lenses come for around ₹15,000 for both eyes. And while I expect that the price may be a hindrance for some to actually use these lenses, from a purely medical point of view I think this is a very interesting development and I do think that this will actually reduce the prevalence of high myopia.