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Dr. Dean

Why Does The Eye Doctor Dilate My Eyes?

Posting Date: 01/26/2001

Doris Marie: What is the eye doctor looking for when he dilates my pupils during my annual exam?

Dr. Dean: There are two reasons; one has to do with prescriptions for glasses and the other is about looking for disease.

The drugs that dilate the pupils actually paralyze the eye muscles that control focusing. Immobilizing these muscles allows for a more accurate gauge of what strength your glasses should be.



Certainly we can measure for glasses without dilation -- in fact optometrists did so for years because the law used to allow only medical doctors to put drops in the eyes. So optometrists figured out ways to do refractions for your glasses without the drops.

Dilation also gives the doctor a view of the back of the eye, which is one of the most fascinating views of anatomy, because the back of the eye is really part of the brain. The first time in medical school that we looked at the back of an eye, the whole class went, "Wow!"

Seeing the blood vessels and nervous tissue that are part of brain tissue, allows the doctor to look for signs of multiple sclerosis, high blood pressure, diabetes, and heart disease -- not to mention the eye diseases like macular degeneration and cataracts that we are at risk for as we age.

They can also see way out to the edge and make sure there are no holes in the retina.

Dilation does carry the risk of bringing on a rare type of glaucoma that would require emergency surgery. The odds of this happening are very small.

So, dilation is a good idea. It's like having a colonoscopy once in a while to check for colon diseases -- you want to open up this part of your body and let the doctor in.