Anisometropia: Can’t Focus? What Happens When Your Eyes Don’t Have Equal Sight

Anisometropia is an eye condition where someone’s eyes have unequal refractive power (the degree where the eye differentiates light). This condition hurts your eye’s ability to focus and can cause severe headaches. Evan Kaufman, MD, explains this condition and how UVA treats patients with anisometropia.

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In Evan Kaufman's words:
With anisometropia, one eye might see perfectly while the other eye doesn’t see well at all. Since eyes work together to see, if one eye is in focus and the other eye is not, a discrepancy occurs in the brain. The brain then tells the eye with the poorer vision to shut down. This will become amblyopic (decreased eyeslight), or you get a really big headache. We see a lot of strenuous headaches and people that have anisometropia. You can help people with glasses with an uneven prescription. The problem that we have with glasses is the further away you put your refractive surface from the eye, it changes the image that is seen. What I mean by that is if you think about Sherlock Holmes and his magnifying glass, he uses his magnifying glass to find clues or to magnify things. Well, if one eye has a magnifying glass on it, which is your prescription, and the other eye does not have a magnifying glass, then one eye sees things that are really big and the other eye sees things that are normal size. And when you have that size discrepancy, you can get a really bad headache. Contact lenses can sit right on top of the eye. Now, when you deal with magnification, because the contact lens sits right up against the eye, the refractive surface is up against the eye. And whether the prescription’s a minus 10 or a plus 20, because it sits on the eye, the distance that the light has to travel to hit the eye is 0 because it's sitting on the eye. Thus, the magnification or minification is 0, so you have zero-size discrimination when you wear contact lenses in a case of a patient that has anisometropia.