An Introduction to Myopia Control (and the Studies that Support It)7:00 AM
|80-90% of school aged children in Asia are myopia -- creating an international|
epidemic of nearsightedness and a quest for a way to intervene via
What We Can Do
|Orthokeratology corneal molds reshape the eye overnight via|
The average childhood eye increases in myopic prescription by a rate of around -0.50D units per year for every year of growth (typically stabilizing in a person's early 20s). The most successful method to date of slowing down myopia progression has been orthokeratology; specialized corneal molds that are worn at night and reshape the eye while you sleep. The CRAYON study and the SMART study demonstrated effective reduction of myopia prescription rate of change, as well as reduced lengthening of the eye (called axial length) with nightly orthoK lens wear. Studies suggest that wearing orthoK lenses reduces the rate of myopia progression between 50-90% and the axial length elongation between 40-80% compared to single vision glasses wear. Wearing these molds will not reverse myopia that has already developed, but they can greatly minimize the speed with which a child's prescription increases if worn nightly during the years of typical myopic growth (usually through the early 20s). Orthokeratology is FDA approved for treatment of myopia up to -6.00D of prescription in the United States.
Safety concerns of wearing these corneal molds over night has also been raised in the past, but studies have proven there is no increased microbial infection risk with orthokeratology lenses compared to that of normal contact lens wear. Orthokeratology microbial infections occurred at a rate of 7.7 per 10,000 users in the linked study, compared to 18-20 per 10,0000 wearer infections in multiple use disposable soft contact lens users.
2) Atropine Drops
While atropine usage is not as popularly prescribed for myopia control in the US, in Asian countries where myopia has become a huge public health issue the number of children being prescribed atropine has skyrocketed in the last decade. In Taiwan nearly 50% of school age children were prescribed this drop for myopia control when surveryed in 2007. Atropine does work -- the ATOM study found that compared to placebo control, children treated with nightly 1% atropine had approximately an 80% reduction in myopic progression rate. Atropine does come with side effects -- most notably a dilated pupil which causes increased light sensitivity and decreased near vision. Children on atropine need to wear bifocal or progressive glasses with tinted lenses through the day to help negate these issues. Some studies show that a lower dosage of atropine (0.01-0.02%) also achieve a level of myopia control but with much less risk of visual symptoms.
3) Soft Multifocal Contact Lenses
Several ongoing studies are investigating the possibility of soft multifocal contact lenses being used to slow the rate of myopic progression, but data has not yet been published on the larger, controlled study designs. The BLINK study is being run by the National Eye Institute and will be reporting data over the coming years. A 2013 study with small sample size showed soft multifocal lenses reducing myopic progression by 50%.
What Doesn't Work
Through the course of research scientists have also found that many methods don't help reduce myopia progression, and can even make it increase faster! Two popular concepts that have now been proven ineffective were the use of bifocal glasses or undercorrecting the myopic prescription. The COMET Study showed no statistically significant benefit in the use of bifocal or progressive lenses in slowing myopia rates compared to wearing single vision glasses. Sometimes I am asked by parents to reduce a prescription for their child in the hopes to keep their Rx lower, but undercorrecting prescription can actually increase the worsening of near sightedness and should be avoided!
If you are interested in pursuing methods to slow down your or your child's rate of prescription increase, please talk to your doctor about your options. Eye care providers around the world can help intervene in how quickly your child's sight is deteriorating, and help keep the level of myopia they have at a controllable level that has less risks for degenerative and possibly blinding conditions even into adulthood.