Your eye doctor will often use eye drops to dilate your pupils.  Dilated eye exams allow a thorough examination of the structures inside the eye.

A dilated eye exam will reveal the status of your optic nerves and the health of your retinas. A dilated eye exam is a way to detect eye problems such as glaucoma and macular degeneration and for detecting vision problems related to diabetes.

How Does Pupil Dilation Work?

Eye drops are used to dilate the pupils which are the round, black openings in the center of your irises—the colored part of your eyes. 

Your irises automatically open and close depending on the amount of light in the environment. Think about how when you enter a dark movie theater you must wait a few seconds before you can see your way around. That wait time is for your pupils to dilate (become larger) so that more light can enter your retinas and you can see your way around in the low-light environment of the darkened theater.  

Dilating eye drops work by blocking parasympathetic receptors in the sphincters (dilator muscles) of your irises. Your pupils stay dilated (open) because they can’t constrict. The muscles that do that constricting are temporarily blocked.

Once your pupils are dilated you will experience an increase in light sensitivity because the wide open pupils are allowing maximum light to enter your retinas even though you are not in a darkened environment. 

Dilated pupils can also make your vision blurry, especially if you are trying to read. Wearing sunglasses until the effects of the dilating drops wear off will help. 

If you are having a dilated eye exam it is a good idea to bring someone along to drive you home.

How Long Does Dilation Take?

Dilating eye drops using take 15 to 30 minutes to fully dilate the pupils.

How Long Does Dilation Last?

The effect of dilating eye drops wear off in 4 to 6 hours.

When to Have a Dilated Eye Exam

  • The National Eye Institute recommends that starting at age 60, everyone should have an annual, comprehensive dilated eye examination.
  • If you are African-American or Hispanic you are at a higher risk of developing glaucoma so the recommended age for the first dilated eye exam is 40.
  • People with diabetes should have regular dilated eye exams because diabetes increases the risk of damage to the blood vessels in the retinas