Astigmatism

Q:  About twenty years ago I was diagnosed with minor astigmatism by an ophthalmologist. During a recent eye exam by the same ophthalmologist, I was told there were no signs of astigmatism. When I asked how this could be, I was told that it can disappear. Is this possible? To me, my vision hasn't changed and I still feel I have minor astigmatism.

A:  Yes, astigmatism can certainly increase or decrease with time due to aging changes in the cornea and lens, and for many other reasons. First let me briefly explain what astigmatism is. We see when light waves enter the eye and are focused by the cornea and lens to produce an image on the retina. Astigmatism is a condition in which light waves are not focused at one point, but rather at two separate focal points because the cornea is not spherical. This produces a blurry retinal image and results in eye strain, so a person must wear corrective glasses.

Bhavna P. Sheth, MD, Associate Professor of Ophthalmology outlined several reasons that alter astigmatism over time: trauma to the cornea or lens, cataract formation, or infections and growths on the cornea. Even compression of the cornea by an upper eyelid stye may cause temporary alterations in the astigmatism. Finally, contact lenses can cause a change in the corneal curvature, usually due to an improper fit. This is almost always reversible with either discontinuing the contact lens, refitting, or changing the type of contact lens worn.

"Dear Doctor" is a compilation of patient questions answered by doctors from the Medical College of Wisconsin.