The dilated portion of a comprehensive eye exam — where the doctor places a few drops in your eyes to open the pupil, allowing a nice view of the back of your eye — is often a hassle. 

While the optometrist needs just a short look to check for vision-threatening eye diseases and other possible signs of health problems, you’re left with a less-than-clear view of the world while your pupils return to their normal size. This can take a “few to several hours,” notes the American Academy of Ophthalmology (AAO). (Other medical groups put the timing between 4 and 24 hours.) 

Sunlight and bright room light can make you wince during this time, so things such as driving or returning to work, school, or sports practice may need to be pushed back. You may also want to pick out frames prior to your exam or schedule a time to come back, since your vision will be blurry for several hours after having them dilated. 

Knowing all of this, it’s natural to wonder if you can say no thanks to dilation. For the answer, we turned to Johnny P. Morette, O.D. He’s an optometrist for Crystal Clear Eye Associates of Florida, located within America’s Best Contacts & Eyeglasses in Winter Garden, Florida. Here’s his take, and what he wants everyone to know about ways a comprehensive eye exam plus dilation can help you protect your vision for life.  

How do dilating drops work?  

These drops affect the muscles that control your pupils and those that focus the lens of the eye. Normally, your pupil expands and contracts in response to the light conditions around you. Dilation keeps your pupils open so your eye doctor can see a much larger portion of the inside of your eye. 

It takes about 20 to 30 minutes for the drops to fully enlarge your pupil. The effects, though, generally last three to four hours, says Dr. Morette. Due to the amount of pigment in the iris — the colored part of your eye — people with blue or green eyes tend to dilate faster than those with brown eyes. But the pupils in people with dark eyes will return to their normal size more quickly.  

Why is dilation important? 

When your pupils are wide open, your eye doctor can see much more of the retina, the light-sensing lining at the back of your eyes. When you’re not dilated, there’s a narrower field of view, which makes it more difficult for your optometrist to view the inside of your eye, Dr. Morette explains. 

Once your pupils are wide open, your eye doctor uses an ophthalmoscope to project light into your eyes. Along with magnifying the view, the scope allows for an even better view of the: 

• Optic nerve (which carries vision signals to your brain) 
• Macula (a tiny area of light-sensing cells responsible for seeing colors and fine detail; it also provides the central vision we need for driving, reading and other activities) 
• Blood vessels in your retina  

Dilation also helps check for conditions like glaucoma, macular degeneration, retinal detachment or tears, and retinopathy (blood vessel problems in the retina) caused by diabetes or high blood pressure.  

When these vision-threatening eye diseases are picked up in their early stages, the outcome is much better, says Dr. Morette. In some cases, your optometrist can recommend steps that would prevent serious symptoms from developing. In other cases that might be further along, treatment to slow progression or reverse course can begin. Dilation is also an important tool to monitor any existing eye health or vision problems. 

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Why is vision blurry afterward? 

Wide pupils make focusing on close objects (like your phone screen or print on a book) difficult, he says. They also let more light into your eyes, which can make driving difficult during the day or even at night, thanks to glare from oncoming traffic and streetlights. 

Does everyone need a dilated eye exam? If so, how often? 

It varies from patient to patient, says Dr. Morette. The National Eye Institute recommends getting a dilated exam every one to two years for the following groups of people: 

• Those over age 60 
• African Americans who are over age 40 
• Those with a family history of glaucoma  

The AAO also suggests getting a baseline dilated exam at age 40. Having a family history of age-related macular degeneration also boosts the importance of dilation. 

The timeline is different if you have certain health conditions or a diagnosed eye condition. People with diabetes and/or high blood pressure usually need at least one dilated exam per year. You’ll also need regular dilated eye exams if you have diabetic retinopathy, glaucoma, or age-related macular degeneration.  

New vision symptoms also warrant dilation, says Dr. Morette. “I will dilate the eyes if they’re experiencing signs of flashes of light and floaters in their vision to look for retinal tears or detachments in the back of the eye. And children may need a dilated exam to confirm whether they need glasses or if a vision problem or accommodational issues [where the eyes can’t hold focus] exist.” 

At the end of the day, follow the guidance of your eye doctor. “Their knowledge of your basic medical history, family history, and health conditions will help them better understand when dilation is warranted,” he says. 

All of this sounds important, but is it ever okay to say no to a dilated exam? 

“Yes. It’s always your right as a patient to turn down services you don’t want to have, including a dilated eye exam,” says Dr. Morette. “If you have to return to work or school, or can’t miss participating in a sporting event, musical performance, or other activity, talk to your doctor about rescheduling this part of your eye exam soon.” 

Just don’t wait too long, he adds. It’s best to return within one to two weeks of your initial examination so nothing important is missed. Another tip from Dr. Morette? When you’re scheduling the appointment, or when the office staff calls to confirm, ask if dilation will be part of the visit. “If you’re not sure, call to check,” he says.   

Does anything make dilation less of a hassle? 

There’s no getting around the after-effects. But planning ahead helps, he says. First, try to schedule your exam during a time when you won’t have a lot of commitments afterward. Let your boss, teachers, coaches, and others know that your vision will be blurry when you return.  

“It’s also a good idea to ask someone to come with you and drive you home,” he adds. (You could also use a taxi or ride-share service.) Remember to bring sunglasses, or ask your eye doctor if they provide disposable sunglasses.  

Finally, if you know you’ll want to look for new frames that day, try to arrive early so you can browse and set aside a few favorites.