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Why the Eye Doctor Uses Those Drops

Through the years, I've used dilating drops on the eyes of thousands of patients. And though patients ask many good questions, one in particular keeps coming up: Patients want to know if those drops are really necessary.

That's easy. They are. The drops enable ophthalmologists to get a far better look at the tiny, complicated world inside your eyes. Different doctors use different-strength drops, but the purpose is the same -- to expand your pupil, that black hole at the center of your iris that lets in light.

The drops I use take about 15 to 20 minutes to work, and will temporarily increase your sensitivity to light and make near vision blurry for a few hours. Oddly enough, the drops last longer in light-colored eyes.

Sensitive to light

My staff tells patients to bring sunglasses to protect against light sensitivity, and to come with someone who can drive them home. Reversal drops are available, but they only cut in half the time it takes your pupils to return to normal.

Once your pupils are dilated, I use a microscope to examine your eyes. I'll look at the lens behind your pupil to check for cataracts, a clouding of that lens. If you develop a cataract, you may need surgery.

I like to get a close look at your retina, which is to your vision as the film is to a camera. I'll check that the retina is intact and not inflamed. A detached retina can result from trauma and may require surgery.

Blood vessel changes

Next, I examine the retinal blood vessels that feed the eyes. Changes in these tiny blood vessels offer clues to many illnesses, including high blood pressure and diabetes. If I see these signs, I'll refer you to your family physician.

It's important for me to get a good look at the optic nerve, a round, pink structure 1.5 mm to 2 mm in size at the back of the eye. This nerve carries images from your eye to your brain. Damage can result from glaucoma, caused by a number of diseases that usually, but not always, cause increased pressure inside the eyes and lead to a loss of sight.

I'll look for signs of infection or tumor and I'll inspect the vitreous humor, a gel that fills the inside of the eye, to make sure there are no signs of bleeding or inflammation. Many of us have floaters or spots in our vision from debris trapped in the vitreous gel.

So if you find those dilating drops a little annoying, remember: Your eye care professional needs them to complete a good exam.

Source: Thomas L. Beardsley, M.D., F.A.C.S., spokesman for the American Academy of Ophthalmology, is an assistant clinical professor of ophthalmology at Duke University Eye Center.