Dilation is a critical part of a comprehensive eye exam. It helps your optometrist spot sight-stealing diseases (such as glaucoma and age-related macular degeneration) in their early stages, when it’s easiest to slow down or reverse the damage. 

“When I look into someone’s eye without dilation, I can only see a small fraction of the interior. But so many diseases happen outside of what you can see in normal exam,” explains Anthony Giallombardo, O.D., an optometrist at America’s Best Contacts & Eyeglasses in Brick, New Jersey. 

Dilating eye drops relax the muscles in your eyes that normally tighten to limit the amount of light that enters your eyes, says Dr. Giallombardo. “The drops work by inhibiting the iris sphincter muscle, so the iris dilator muscle takes over and makes our pupils really big,” he says. (The iris is the colored part of your eye.) 

Letting in more light gives your eye doctor a wider, more detailed view of the health of your eyes. That’s why the American Optometric Association recommends a comprehensive eye exam, which usually includes dilation, at least: 

• Every two years for adults ages 64 and younger 
• Every year starting at age 65 
• Every year, or more often as recommended by your eye doctor, if you have or are at risk of eye conditions 

While it usually takes just 20 to 30 minutes for dilation drops to widen your pupils, dilation has side effects that can linger for several hours as they wear off. During that time, your pupils won’t be able to constrict normally. Your eyes will be extra sensitive to bright light, your vision will be blurry, and tasks such as reading may be difficult, Dr. Giallombardo says.   

Here’s what to expect, plus five tips to help you stay comfortable and safe after your eyes have been dilated. 

Has it been a while since your last eye exam? Now’s the time to book an appointment! 

1. Bring Your Sunglasses 

“The main negative effect of dilation is light sensitivity,” says Dr. Giallombardo. “Sunglasses would be very helpful to have.” 

That’s because dilation makes your pupils bigger and stops them from narrowing the way they normally do. This exposes more of your eyes to light (including the sun’s ultraviolet rays). 

While your eyes return to normal, it’s a good idea to wear sunglasses during your trip back home and when you’re outdoors. (Pro tip: You should really be wearing sunglasses anytime you go outside, even on cloudy days.)  

2. Ask Someone to Drive You Home 

Glare from bright lights (the sun during the day and headlights and streetlights at night) plus some lingering blurry vision from the drops could make driving yourself home especially challenging. 

“Having a driver is definitely helpful,” says Dr. Giallombardo. Ask a friend or family member if they can drive you home from your eye exam. 

If that’s not possible, play it safe and stay back in the waiting room — or browse the frame selection — for a few extra minutes after your exam has wrapped up. Give yourself that cushion time for your pupils to shrink a bit. 

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3. Take It Easy with Reading and Close-Up Work 

Normally, the sphincter muscles in the irises of your eyes tighten up quickly when you shift your gaze from something far away to something nearby, such as looking at a message on your phone after looking out a window. This helps keep near vision sharp. But after a dilated exam, those muscles won’t do that until the drops wear off.  

“The second negative effect from dilation is that we lose our ability to accommodate, and our eyes can’t focus on things up close,” says Dr. Giallombardo.  

That could make reading difficult for a few hours too. If you normally wear reading glasses for myopia (nearsightedness), you may find it’s easier to read without them during this time, he says. Dimming the brightness of your computer, tablet, or smartphone screen may also help ease eye discomfort while reading. 

4. Consider Taking a Few Hours Off of Work 

Blurry vision, difficulty reading, and light sensitivity can make it tough to work in the hours following a dilated eye exam. Your eyes may also feel fatigued and heavy after an eye exam that includes dilation, notes the Glaucoma Research Foundation. 

Some eye doctors suggest scheduling your eye exam for later in the afternoon so you can work most of the day, then go home after your eye check. 

5. Try to Be Patient While the Side Effects Wear Off 

The side effects of eye dilation typically last four to six hours, says Dr. Giallombardo. But there are all kinds of factors that affect that duration, including your eye color. Green and blue eyes tend to dilate faster than brown eyes, Dr. Giallombardo says, and they may also take longer to return to normal afterward. 

The hours after a dilated eye exam may be a bit uncomfortable or frustrating. But try to be patient. Your eyes will return to normal soon, and you can rest easy knowing you did your eyes a huge favor. 

Medically reviewed by Anthony Giallombardo, O.D. 

See our sources:  
Importance of dilated eye exams: National Eye Institute 
Dilating eye drops overview: American Academy of Ophthalmology 
Comprehensive eye exam overview: American Optometric Association 
Glaucoma tests: Cleveland Clinic 
What not to do after dilation: All About Vision 
Is eye dilation necessary at every eye exam? Mayo Clinic