I have been a contact lens wearer for more than five years, and I think they are great. A few seconds in the morning gives me the gift of perfect sight without having to wear a primitive piece of eyewear on my face. Unfortunately, the second I take them out for the night, I am essentially blind at distances further than an arm’s length! I am certainly not alone. According to the American Optometric Association, nearly thirty percent of Americans are affected by myopia (nearsightedness) caused by an elongated eyeball and/or incorrect curvature of the cornea. Light entering the eye does not do so in proper focus. Contact lenses and glasses correct this. Myopia can be inherited genetically and provoked by environmental factors. I can say that my vision is definitely worse now than it was five years ago. I have chalked this up to some sort of “dependence” that I have developed as a result of corrective lens use and I have accepted it as a natural consequence of wearing them every day. This Nigerian study found that 64 percent of students feel the same way. Is there validity to this belief? Would people be wise to wear their lenses sparingly to avoid worsening myopia? Furthermore, is there a difference between contact lenses and eye glasses with regards to myopic progression?
A simple google search will return advice from many laymen claiming the affirmative- that corrective lenses do in fact worsen eyesight. The science, however, leads in a different direction. Testing this is not easy because it is normal for eyesight to naturally worsen with age, but this study offered valuable data. The scientists assumed that if it were true that prescription glasses worsened eyesight, then it would be logical to under correct eyesight to slow that deterioration. To study this, 94 children aged 9 to 14 were randomly assigned to two groups. The control group was fully corrected while the experimental group was given prescriptions that were .75 units below what would correct them fully. Their eyes were measured yearly. The results of the study were surprising: the control group eventually leveled off while the experimental group experienced elongated eyes and worsening vision. This study debunked the idea that a weaker prescription will slow myopic progression by proving that doing so in fact accelerates it. Those with proper prescriptions did not experience worsening vision as a result. Interesting note on this study: This study was actually a rare example of one that had to be stopped prematurely because the results were so immediately obvious. We discussed ethics in class with regards to this type of occurrence. Researchers concluded that to continue the study would be unnecessarily harmful to the experimental group. Under correction is no longer an acceptable practice for attempting to slow myopia.
The take away so far is that worsening nearsightedness as a result of corrective glasses is a complete myth. But does the same hold true for wearers of contact lenses? According to a project called Adolescent and Child Health Initiative to Encourage Vision Empowerment (ACHIEVE), children who wore contact lenses experienced no clinically relevant increases in myopic progression. They determined this by randomly allocating 484 children who had not previously worn contacts into two groups: one that wore contact lenses and one that wore glasses. They then studied the progression of myopia in the two groups to determine that there was no statistical difference.
Take away: The notion that nearsighted people will experience more rapid eyesight deterioration by wearing corrective lenses is false. Under correcting to avoid worsening of eyesight will actually worsen it! Contact lenses are safe with regards to myopic progression.
Note: The pictures themselves are links to their respective source.