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Dilation is part of a thorough eye exam. You may think it’s a hassle. But it gives your doctor a good look inside your eye. It’s especially important if you’re having eye pain or vision problems, or if you’re more likely to get certain eye diseases.

Normally, your pupil gets smaller when light shines into it. In dilation, your doctor uses special eye drops to force the pupil to stay open. That allows him or her to see much more of the back of your eye, including the entire retina, the part of the retina called the macula, and the optic nerve.

During a dilated exam, your doctor can spot problems like a torn or detached retina or an eye tumor. They can also diagnose and monitor common eye diseases that can take away your sight:

How Long Does It Last?

Everyone’s eyes react differently to the dilation drops. It usually takes 15 to 30 minutes for your pupils to open completely. Most people are back to normal within about 4 to 6 hours. But for you, the effects could wear off more quickly, or they could last much longer.

Can I Drive?

Dilation doesn’t typically affect your distance vision. But because your pupils can’t control the amount of light going into your eyes, the glare outside may bother you. For some people, that makes it unsafe to drive.

If you’ve never had your eyes dilated, get someone else to drive you home from your appointment. Once you’ve had it done, you’ll know whether dilation means you can’t drive after an exam.

Whether or not you get behind the wheel, it’s a good idea to bring sunglasses with you so you can shield your eyes after the exam.

Can I Go Back To Work?

Dilating drops make it hard for your eyes to focus on things close to you. You probably won’t be able to read, use the computer, or do other tasks that require near vision after your appointment, unless you wear bifocals or use reading glasses. If you work outside, the bright light may bother you. It may be easier to make an appointment later in the day so you don’t have to go back to work.

Can Advanced Technology Replace Dilation?

Many eye practices will say “No Dilation Necessary. New State of the Art Technology Available.” Doubtless, “no dilation” appeals to patients who don’t like getting dilated, with the time and discomfort required. But there are dangers to this approach.

Advanced technology, like Optomap, offers greater power to diagnose and manage ocular disease, but think twice before you use it as a replacement for dilation. There is no technology that replaces dilation for thoroughly assessing eye health.

There are limitations to the device. One of the main limitations is that it does not image all of the retina. There are parts of the retina superiorly and inferiorly that are missed by Optomap, usually because those areas seem to be limited or blocked by the upper and lower lids.

In 2017 a study was published in Seminars in Ophthalmology, which examined 36 eyes of 34 patients, and retrospectively compared the use of Optomap to indirect ophthalmoscopy (dilated eye exam) in evaluating patients with a history of with non-traumatic retinal detachments. The study found that “ultra-widefield imaging failed to detect retinal pathology in the superior and inferior quadrants in 11.1% and 19.4% of cases, respectively [and in] postoperative imaging, UWF photos did not detect retinopexy scarring which was ophthalmoscopy-visible both superiorly and inferiorly in 19.4% of cases.”

The study concluded that while “ultra-widefield imaging is a useful adjunct for documentation of retinal detachments and their postoperative repair, the detection of retinal holes, tears, and postoperative scarring is poor, especially in the inferior and superior periphery.”

How Often Do I Need It?

Dilated and Undialated Eye

The National Eye Institute recommends everyone over 60 have a dilated exam once a year. If you’re African-American, you’re at higher risk for glaucoma, so the yearly recommendation starts at age 40. If you have diabetes, you should also have a dilated exam once a year no matter how old you are.

Dilation is often a normal part of an eye exam for people who wear glasses or contacts. But if you’re young and your eyes are healthy, you may not need it every time. Your doctor also may be able to use other methods to check your retina without dilating your eyes, but they may not work as well. See what your doctor recommends.

Many eye diseases are more common as you get older. The American Academy of Ophthalmology says everyone should get a baseline exam with dilation when they’re 40. That way, your doctor can track any changes that could signal a problem.

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