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What is a Dilated Eye Exam?

Many people think their eyes are completely healthy, but only an eye doctor can tell you this definitively after an eye exam. Some conditions, like macular degeneration, have no symptoms in the early stages of the disease but do show signs on a clinical exam. This is why it’s so important to get regular eye exams, especially as you get older.

Comprehensive dilated eye exams

A yearly comprehensive dilated eye exam is recommended for individuals over the age of 60; for African-American individuals, it’s suggested to have yearly dilated eye exams after the age of 40, because of a higher risk of glaucoma.1 Early detection of disease can be helpful since there are things you can do to help preserve your remaining vision and improve overall eye health. Treatment early on in diseases also tends to be less invasive and may help reduce symptoms and improve quality of life.

There are several parts to a comprehensive dilated eye exam: visual acuity, pupil assessment, eye pressure (tonometry), visual field, and finally a dilated fundus exam.1

Visual acuity test

This is the standard eye chart exam and gives your doctor an idea of how well you can see shapes and details from specific distances.

Pupil assessment

Your doctor may shine a light in each eye to check if your pupils constrict normally and equally.

Tonometry

Tonometry is the measurement of pressure inside the eye. There are several ways to check eye pressure; there is a tool that shoots a short puff of air on your eye, or a pressure-sensitive tip might be pressed gently against the surface of the eye. The force with which the eye pushes back helps to measure the pressure inside the eye.2 If eye pressure is elevated, your doctor may discuss your risk for developing a condition called glaucoma.

Visual field test

A visual field test measures central and peripheral vision. The machine automated version of the test often consists of a spot of light that is repeatedly presented in different areas of your central and peripheral visual fields.3 If there is no machine, a technician can manually move a target to estimate your visual field. Visual fields may be followed over time in order to check for new blind spots.

Dilated fundux exam

Dilation allows your eye doctor to see the back of your eye, also called the fundus, and is usually the last part of the eye exam. Dilating eye drops are placed into your eyes (this doesn’t hurt, although it might sting a little bit for a few seconds) that enlarge the pupils, allowing more light in.1 The doctor then uses a magnifying lens to examine the eye, since they will be able to now see structures at the back of the eye, like the macula, peripheral retina, and optic nerve.1 This is especially important for diseases like AMD, glaucoma, and diabetic retinopathy.

Other testing and imaging

As part of a comprehensive dilated eye exam, your eye doctor may also take scans, photographs, or other images of the back of the eye using various machines.

When someone goes to the eye doctor, not every exam includes dilation. However, for individuals over the age of 60 and those at risk for macular degeneration, one should have a comprehensive eye exam that includes dilation, so your doctor can get a complete picture of your eye health. If you’re not sure whether the exam will include dilation, you can always ask ahead of time and request a dilated exam.

Jaime R. Herndon | January 2019
  1. National Institutes ofHealth: National Eye Institute. What Is a Comprehensive Dilated Eye Exam? n.d. https://nei.nih.gov/healthyeyes/eyeexam. Accessed October 17, 2018.
  2. Johns Hopkins Medicine. Tonometry. n.d. https://www.hopkinsmedicine.org/wilmer/services/glaucoma/book/ch06s01.html. Accessed October 18, 2018.
  3. Momont, A & Mills R. Why Do I Need a Visual Field Test? Glaucoma Research Foundation website. 2017. https://www.glaucoma.org/treatment/why-do-i-need-a-visual-field-test.php. Accessed October 18, 2018.