Getting your eyes dilated is an important part of any complete eye exam. Once your doctor puts in the dilating drops, it takes about 20–30 minutes for your pupils to fully open, or dilate. After your eyes are fully dilated, the effects will last for four to six hours for most people.

Some people feel the effects of dilating drops for longer, including . Dilation in children can last up to a full day after the exam.

It’s impossible for your doctor to tell you exactly how long the effects of dilation will last and how severe they will be. Everyone’s eyes react differently to dilating drops. The important thing is to use caution as long as your vision is blurry or your eyes are light sensitive.

Dilation is harmless in the long term, but it does come with short-term side effects. These will usually last for about four to six hours.

Side effects of dilation include:

  • light sensitivity
  • blurry vision
  • trouble focusing on close objects
  • stinging right after the drops are put in

If you wear lenses, you may not be able to wear them until the dilation drops wear off.

Dilation allows an eye doctor to look inside your eyes. Dilating drops widen the pupil (the black part of your eye) so that it doesn’t get smaller when your doctor shines a light at it. The widened pupil allows your doctor to use a magnifying lens to look inside your eye and at the back of your eye. They’ll look at the retina, optic nerve, blood vessels, and other parts of your eye that can’t otherwise be seen.

Dilation helps your eye doctor diagnose many eye conditions, including

It also helps diagnose some chronic conditions that affect more than your eye, such as high blood pressure and diabetes. This is because those conditions can lead to changes in the eye. For example, high blood pressure could damage the blood vessels in your retina, which can be seen only when your eye is dilated.

Dilation as a treatment

Dilating drops can also be used to treat certain eye conditions. These include eye inflammation and amblyopia, also called a lazy eye, which is a condition where one eye doesn’t properly connect with the brain. Dilating drops used as treatment have the same effects as drops used during exams.

Dilation can cause blurry vision and light sensitivity, so it’s important for you to take care of yourself and your eyes after your appointment.

  • Have a friend or family member drive you home from your appointment, or take a taxi. Many people drive themselves home if they’ve experienced dilation in the past and feel comfortable doing so.
  • Bring sunglasses to protect your eyes after your appointment. Sunlight might hurt your eyes. Your doctor’s office might offer sunglasses after dilation, but bringing your own never hurts.
  • Take a few hours off work if possible. Reading may be hard, and it’s important to not strain your eyes.

Eye exams aren’t just to check your vision. They can also help diagnose diseases, both those that affect the eye only and other chronic conditions. It’s important to have regular eye exams even if you don’t have any vision problems.

If you or your child don’t have any eye issues and aren’t at high risk for them, schedule a complete eye exam every two years. A complete exam includes dilation. Schedule an eye exam every year if you or your child:

  • wear glasses
  • have diabetes
  • have any eye conditions
  • have a family history of eye conditions
  • are at risk for eye conditions

Annual eye exams are also recommended for all adults over 60, regardless of any eye conditions. African-Americans and Hispanics should have annual eye exams beginning at . That’s because both of these groups are at a higher risk for glaucoma.

Dilation may be uncomfortable or inconvenient for a few hours, but it’s an essential part of health screenings. Dilation can help your doctor diagnose not just eye conditions, but other health conditions as well. Having an eye exam with dilation every one to two years will help keep you and your eyes as healthy as possible.