After being diagnosed with diabetes, you might be surprised when your doctor tells you to schedule an eye exam. Many people don’t realize that diabetes can affect eye health — sometimes before you notice any changes in your vision.

The good news is that there are many eye exams designed to detect these changes early and help protect your sight. Here are the basics so you’ll know what to ask for when you make your appointment.

Diabetes and Your Eyes

Diabetes can affect your eye health. There are a few ways it can do this.

First, high blood sugar levels can cause changes in your retina. This is a thin layer of nerve cells that lines the inside of the back of your eye. High blood sugar can make it hard for the blood vessels in the retina to function properly. This is called diabetic retinopathy. If these blood vessels leak fluid into your macula, the small central part of the retina that helps you see fine details, your vision can become blurry. This is called macular edema.

Diabetes is also associated with cataracts, which cause your vision to become more and more cloudy. People with diabetes are also more likely to develop glaucoma, a condition where pressure builds up in the eye. Glaucoma can damage the optic nerve. Diabetes may also make your eyes dry, which can cause vision problems and lead to other eye conditions.

All of these issues can affect your vision in significant and sometimes permanent ways. Regular diabetic eye exams can help find these problems before that happens. Then, you can get treatment so your vision isn’t affected.

It’s recommended that people with diabetes see an eye care specialist like an ophthalmologist or an optometrist. They should go every one or two years, depending on what the doctor says. Most people living with type 1 diabetes need to go every year. Those with type 2 diabetes should go soon after they’re diagnosed, then follow the doctor’s instructions after that. If you have diabetes and you want to get pregnant, go before you conceive. If you’re already pregnant, go during your first trimester and follow the doctor’s instructions after that. Pregnancy may cause additional problems with your eyes when you live with diabetes.

Eye Tests for Diabetes

Your eye doctor will decide what tests you need. Your doctor may not perform all the eye tests listed, but here are some of the most common eye exams for people with diabetes.

1. Dilated Eye Exams

During a dilated eye exam, your healthcare provider will put drops in your eyes that cause your pupils to enlarge (also called dilation). This lets the doctor see the inside of your eye in a lot more detail. It normally takes between 15 and 30 minutes for your pupil to dilate. Then, your doctor can easily see if you’re dealing with retinopathy, nerve damage, or macular edema. Some of the other tests listed here may be done while your eyes are dilated.

The drops affect your eyes for a couple of hours. You’ll be sensitive to light, and your vision might seem blurry. For this type of test, it’s best not to go alone. You’ll want to wear sunglasses after your appointment and have someone else drive you home.

2. Visual Acuity Tests

Visual acuity tests measure how well your eyes are seeing. These tests can tell you if you need to wear glasses or contacts to correct your vision. If your blood glucose is changing or increasing a lot, it may affect how well you can see. Thus, these tests also help your doctor track your diabetes.

Most of the time, these tests ask you to name letters that you can see. The letters get bigger or smaller and help your doctor determine how well you’re seeing.

3. Optical Coherence Tomography

Optical coherence tomography (OCT) is technology that allows your doctor to take scans and photographs of your retina and optical nerve. Your doctor can then examine these in detail to make sure they haven’t missed anything. The images from these scans can be useful in detecting almost any eye disease. The images can also help your doctor determine how thick your retina is, which can help diagnose diabetic macular edema.

This test isn’t invasive. This means that they don’t have to put anything inside your body. OCT is usually an easy test where all you have to do is sit in front of a machine and follow a few instructions.

4. Fundus Photography

Fundus photography is another way that your eye doctor can get images of the inside of your eye. Fundus photography specifically focuses on the retina, so it’s useful in diagnosing or monitoring any eye issues that involve that part of your eye. All you’ll need to do is sit in front of the camera, put your chin on a chin rest, and follow directions. Your doctor will get the photos they need to evaluate your eye health.

5. Eye Pressure/Tonometry

Eye pressure tests simply measure the pressure inside your eye. They’re good for figuring out if you have glaucoma. Your doctor will simply ask you to keep your eyes open while they perform the test. There’s nothing else you need to do. If the test is uncomfortable for you, your doctor may use a drop that will numb your eye before they do the test.

6. Extraocular Motility

Extraocular motility tests look at how well your eyes move around. Your doctor will usually have you focus on an object. Then they’ll move that object in several different directions and ask you to follow it with your eyes without moving your head. This helps them spot problems, especially if there’s a significant difference between your eyes. Occasionally, diabetes that isn’t under control can affect how well your eyes move.

7. Visual Field Test

A visual field test looks at how wide you can see when your eyes are focused straight ahead. This test helps your doctor see how well your retina and optic nerve are doing and can also screen for glaucoma. Both the retina and optic nerve can affect how well you see, especially your peripheral vision.

Most doctors do this test by having you sit still and look straight ahead. They’ll put a certain number of fingers or certain fingers up at different points around you. Then, they’ll ask you how many fingers or which finger they used, all while you continue looking straight ahead. If you don’t know, they may try moving their fingers a little closer to you. This helps the doctor understand how much peripheral vision you have. If your vision gets worse over time, a visual field test can help the doctor monitor the progression of any eye disease you’re dealing with.

Talk With Others Who Understand

On DiabetesTeam, people share their experiences with diabetes, get advice, and find support from others who understand.

Which eye exams have you had since being diagnosed with diabetes? Let others know in the comments below.