Retinal imaging takes a digital picture of the back of your eye. It shows the retina (where light and images hit), the optic disk (a spot on the retina that holds the optic nerve, which sends information to the brain), and blood vessels. This helps your optometrist or ophthalmologist find certain diseases and check the health of your eyes.
Doctors have long used a tool called an ophthalmoscope to look at the back of your eye. Retinal imaging allows doctors to get a much wider digital view of the retina. It doesn’t replace a regular eye exam or regular dilation,, but adds another layer of precision to it.
Who Gets This Test?
Your doctor may recommend it if you have any the following diseases or conditions:
Macular degeneration: The central part of your retina (the macula) starts to get worse with age. You may have blurry vision and find it harder to focus. If that happens, you may be considered legally blind even though you may still have peripheral vision. There are two kinds of macular degeneration: wet and dry.
Dry macular degeneration is by far the most common form of this disease (up to 90% of the cases). It happens when blood vessels under the retina become thin and brittle.
Abnormal blood vessels growing under the retina cause wet macular degeneration. Vision loss is usually fast.
Retinal imaging is very important in finding this type of macular degeneration.
Glaucoma: This disease damages your optic nerve (located in the retina) and may cause vision loss. It typically happens when fluid builds up in the front of your eye. It can cause blindness but it normally progresses slowly and can be treated with special eye drops to lower the pressure caused by the fluid.
Your doctor may also use retinal imaging if your vision is getting worse and they aren’t sure why.
What Happens During the Test?
The doctor may dilate your eyes with special drops. This widens your pupils. It will take about 20 minutes for your eyes to be ready for the examination.
Next, you'll place your chin and forehead on a support to keep your head steady. You'll open your eyes as wide as possible and stare straight ahead at an object while a laser scans your eyes. The images are uploaded to a computer so your doctor can look at them.
If the doctor thinks you might have wet macular degeneration, you'll probably have a fluorescein angiogram. For this test, they’ll place an IV needle in a vein in your arm and inject a dye. As the dye enters your eye, it highlights the blood vessels so pictures can be taken.
The regular test takes 5 minutes. The fluorescein angiogram takes about 30 minutes.
What Happens After the Test?
If your eyes have been dilated, your vision will be blurry for about 4 hours. You’ll be sensitive to sunlight too. You'll need to wear sunglasses and have someone drive you home.
If the fluorescein dye was used, do not put soft contact lenses in your eyes for about 4 hours so they don’t get stained by the dye.
The images from the test should be ready immediately and normally your doctor will talk to you about them before you leave.
What Are the Benefits and Drawbacks?
Retinal imaging allows eye doctors to see signs of eye diseases that they couldn’t see before. The test itself is painless and the results are easy for doctors to interpret. Your doctor can store the images on a computer and compare them with other scans.
Retinal imaging has its limitations. It can’t detect a disease where the retina is bleeding. It also may not see problems on the outer edges of your retina.