DP EyeCare Update: Corneal topography
Q: I have heard that many kids get more nearsighted as they grow, but my 17 year old seems to have more astigmatism every year. Is this common and what causes this?
A: You are correct in that far too many children are becoming very nearsighted at a faster rate than ever before. Fortunately, new techniques in “myopia control” can slow or stop that progression. The same cannot be said about astigmatism.
First, astigmatism is simply one of the top three types of blurry vision, and generally is caused by the shape of the eye. Specifically the front layer, called the cornea is not round like a basketball, but rather shaped like the side of a football. That “bent” surface bends the light entering the eye causing a type of blurred vision.
My concern for your son would hinge upon knowing the shape of his corneas. Measuring and mapping the corneal shape is called “corneal topography”, or CT. In our practice we use CT imaging for every contact lens wearer to be sure the eye surface is not swelling and the health is normal. We also use CT for any young patient with progressive astigmatism to diagnose the cause of this uncommon development.
I said “young” patient, because diseases of the cornea that can cause vision distortion generally begin early in life…..teenage years, in particular. So, anyone under 30 with progressive or rapid changing astigmatism should first have CT imaging done. Frankly, we worry most about corneal dystrophies like keratoconus. This usually begins early in life ( almost never over age 50 ) and makes our cornea become thinner and more pointed, or “cone-shaped”. Accurate diagnosis is so essential, because early intervention can virtually stop the progression and protect clear sight. Untreated keratoconus can cause irreversible vision distortion, with only very difficult surgery options and more tenuous outcomes.
Today, if caught early, medication treatments and special “scleral” contact lenses can stop progression and keep clear sight for your whole life……without any surgery. Because this is a “young person’s disease”, we often encounter skepticism from parents about CT imaging for something as common as astigmatism. Keratoconus is certainly not well known in the general public, and poorly understood. The new treatments are proving to be not perfect , but very good…..and in my opinion, far better than any corneal surgeries.
Be sure your eye doctor is using CT imaging for your son, and not just prescribing stronger glasses every year. Not every practice has the technology to perform CT imaging, so you may need a referral. Nonetheless, step one is to rule out any corneal dystrophy that could be driving this progressive vision change for your son.