Summit Eye Center Blog

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Why do they dilate my eyes?

graphic depicting impact of eye dilation

You may ask yourself...why do they dilate my eyes when I see the eye doctor? Is it really necessary? We want to answer that question today.

The short answer is that by dilating the eye, it allows the doctor to get the best view possible of the back 2/3 of the eye.

To dilate the pupil, drops are placed in each eye to widen the pupil, the opening in the center of the iris (colored part of the eye). Similar to how lifting a window shade allows light into a room, dilating the pupil allows more light to enter the eye.

Once the eye is dilated, the doctor will use a magnifying lens that provides a clear view of the tissue in the back of the eye, including the optic nerve and retina. This is important because 3 of the most common age related eye conditions occur in the back of the eye.

1. Diabetic Retinopathy, a leading cause of blindness, is detected by the doctor looking for swelling or leaking of blood vessels within the retina.
2. Age-related Macular Degeneration, a common cause of vision loss, is initially diagnosed by looking for yellow deposits called drusen and pigmentary changes with in the retina.
3. Glaucoma is a disease of the optic nerve, which relays information from the eyes to the brain. The dilated exam allows the doctor to exam the shape and color of the nerve fibers with the nerve.

A photo, from a camera, of different parts of the retina and optic nerve are useful in documenting findings observed during a dilated exam. However, they don’t equal or replace the view the doctor gets looking through the dilated pupil with the magnifying lens.

If you need to schedule a dilated eye exam, call Summit Eye Center at (816) 246-2111 or email This email address is being protected from spambots. You need JavaScript enabled to view it. to schedule an appointment.

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