New Vision For Myopia
Battling shortsightedness in Singapore with new treatment approaches
A silent epidemic across Asia, myopia affects many children between the ages of six and twelve. Research indicates that a quarter of them require glasses by the age of seven, and eight in ten Singaporeans are myopic by the time they are 18 years old.
In Singapore where the incidence of myopia has grown, optometrists are seeing younger customers, some of whom are as young as four years old. In fact, children are being diagnosed with short-sightedness of about two to three dioptres and in some cases, as high as four dioptres.
Significance of myopia prevention
There is a significant drive to control myopia in children so as to reduce the pool from which high myopia – defined as that higher than six dioptres – develops. Typically, the condition has been treated with concave corrective lenses or contact lenses that help to compensate for the elongation of the eyeball by refracting light more accurately onto the central part of the retina – the fovea.
To keep it under control, regular checks are needed during which the optometrist will also look out for eye problems and risks associated with high myopia.
In Singapore, the average cost of normal vision correction is about $500 a year. This increases once a person enters the high myopia bracket. There are also other associated ‘costs’, e.g. lifestyle limitations and impact on one’s job and productivity.
Getting to the root of the problem
Needless to say, the treatment of myopia is as much a commercial venture as a scientific endeavour. In developing innovative therapies, one must first understand the root of the problem.
The eye works like a film camera, but instead of focusing images on film, it does so, on the light-sensitive membrane called the retina. Myopia develops when the eyeball grows longer, causing the image to form in front of the retina. This causes blurred vision.
In childhood myopia, evidence suggests that progressive childhood myopia is predominantly caused by inherited genetics. Other factors such as long periods of close work and childhood illnesses may also exacerbate its progression.
So what exactly causes the deterioration of vision? Peripheral Blur Theory, studied some 40 years ago, has been garnering more scientific attention of late. Early research studies indicate that the processing of blurred images that fall outside of the central retina,
i.e. the peripheral retina, plays a significant role in how the eye’s optical system changes through the years. In theory, the minimisation of peripheral blurriness will help reduce the severity of myopia progression.
Conventional ophthalmic lenses, which cause peripheral blur, may not be the ultimate solution. So far, we have seen the development of special hard contact lenses or Ortho-K, which can reduce peripheral blur. Worn only at night and work, they have the ability to reshape and flatten the central part of the cornea, leaving the periphery untouched to correct vision.
Another method involves the use of atropine, a prescription-only eye drop which acts on the reflex action of the eye and reduces axial elongation. The Singapore Eye Research Institute in 2010 studied 400 children between the ages of 6 and 13 and found that, compared to the control group, those using atropine experienced a slow-down in myopia progression (0.03 D in the first year and 0.280 D in the second year). The control group saw myopia increase by 0.77 D on average in the first year and 1.20 D in the second year.
New corrective lenses for children
To tackle the issue of childhood myopia, companies like Carl Zeiss have developed non-invasive solutions that have shown positive clinical results. A new lens called MyoVision from ZEISS addresses the problem of peripheral blur based on a unified vision theory.
Conventional lenses refract the image to correct vision, but only on the fovea, causing hyperopic blur in the peripheral retina. The aim of this novel lens design is to try and control eye growth by not only placing the central image on the retina but also decreasing hyperopic defocus and placing the image on or in front of the peripheral retina.
Initial research with some 210 myopic Chinese children aged 6 to 16 at the Zhongshan Ophthalmic Centre in Guangzhou are showing promising results in a sub-group of children aged between 6 and 12 years of age and who had a history of parental myopia. The research indicated that there was a 30 per cent reduction in myopia progression in these children. Extrapolating this data, it means that if myopia progression can be reduced over time, a child that would have a prescription of -4.00D at age 18, instead of -6.00D.
These lenses have the benefits of being practical, safe, easy to use and preventive. Compared with Ortho-K and atropine, there are no proven side effects. Encouraging results from the clinical trials signal an important shift in the treatment of myopia using this new generation of optical devices.
Myopia is a widespread problem in Asia and is alarmingly prevalent among the young. As we gain new insights into new therapies, coupled with recommended lifestyle changes, we hope to stem the tide of progressive myopia particularly in this part of the world.