Myopia or nearsightedness has become more common throughout the world, particularly in urban Asia. It affects 40 per cent of Americans and nearly 90 per cent of schoolchildren in urban east and south Asia. Twice as common as obesity, it is truly an epidemic. In contrast, in rural, low-resource areas, myopia affects only 2-5 per cent of the population.
Across many species, the eye normally grows to focus light on to the retina. The eye grows rapidly in the first two years of life, and continues to grow to age 21 or 22. If the eye grows too long and has an oval shape instead of round, it causes nearsightedness. But in general, eye growth is driven and controlled by guidance from the peripheral retina—the tissue at the back of the eye that converts light into sight.
Scientists have recently discovered that the peripheral retina is more important than the central retina in controlling eye growth. This has led to new types of glasses and contacts to help the peripheral retina. If there is a serious condition blocking light transmission such as congenital cataract, corneal problems or blood inside the eye, abnormal eye growth ensues.
More commonly, the lack of sufficient stimulation of the peripheral retina by sunlight and distance visual activities seems to be triggering abnormal eye growth.
The causes of nearsightedness are not fully understood. We know that genetics play a role: parents who are highly myopic tend to have children who suffer from it as well. Much research has found that increased screen time and decreased outdoor playtime are responsible for much of the recent increase in nearsightedness. Children with normal vision spend 3.7 more hours per week outdoors than those who are nearsighted. Further, in cold climates, myopia progression is significantly faster in the winter. Lots of near work—playing computer games, using iPads, very close reading—also tends to increase nearsightedness.
As a parent, make sure children have plenty of time for outdoor play and minimise screen time early in childhood. Also, make sure that your child’s school has time for outdoor play and has classrooms well-lit with natural light.
If your child has developed nearsightedness, make available custom-fit glasses or contacts. You may have heard that glasses make myopia worse—this is a myth, and a dangerous one. Properly fit glasses at the correct power do not harm vision. However, children should not wear glasses not prescribed to them.
Wearing glasses that are the wrong power may distort vision, causing eye strain or even making vision problems worse.
In addition, there are some medical options that slow down the progression of myopia:
*Atropine 0.01 per cent eyedrops, which can dilate the eye and reduce reading ability temporarily, have been shown to slow progression by 60 per cent when given to children once a day between the age of 6 and 12.
*Peripheral defocus contact lenses, which slightly blur the image in the peripheral retina, can slow down eye growth as well.
The good news about nearsightedness is that there are many ways to treat it. For adults who are unhappy with glasses, LASIK or other types of eye surgery like photorefractive keratectomy and implantable contact lens can be used to improve vision and reduce or eliminate the need for glasses or contacts.
The bad news is that highly myopic individuals are more likely to experience some other eye problems such as glaucoma, cataract or retinal detachment. If you are a -5 or above, make sure to get a dilated eye exam at least every two years as early detection is the key to preventing vision loss.
The views expressed here are strictly those of the author and the university takes no position on these.