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 (eye doctor) find certain diseases and check the health of your eyes.
"Retinal imaging includes several types of cameras that can look at the back of the eye in different ways," says Colin A. McCannel, MD, FACS, FRCS (C), professor of clinical ophthalmology and chief of the retina division at UCLA Stein Eye Institute.
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 Is Retinal Imaging For?
Retinal imaging can be important if you have certain eye diseases or conditions that could affect your eyes. It can help your eye doctor get more information about a condition found during an exam, as well as check for and record any changes in the condition over time, McCannel says.
Your doctor may recommend it if you have any of the following diseases or conditions:
Diabetes. This disease can damage the blood vessels in your retina. Over time, it causes you to lose your sight if it's not controlled.
Macular degeneration. The central part of your retina (the macula) starts to worsen 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.
- Wet macular degeneration is caused by abnormal blood vessels growing under the retina. Vision loss is usually fast.
Retinal imaging is very important for 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 advances slowly and can be treated with special eye drops to lower the pressure caused by the fluid.
Retinal toxicity. The arthritis drug hydroxychloroquine (Plaquenil) can damage your retina.
Your doctor may also use retinal imaging if your vision is getting worse and they aren't sure why.
Sharon Fekrat, MD, FACS, FASRS, a professor of ophthalmology and vice chair for faculty affairs in the ophthalmology department at Duke University, says retinal imaging also might benefit people who have:
- Nearsightedness (myopia)
- A family history of retinal diseases
- Vision changes, such as blurriness, floaters, flashes, or loss of peripheral (side) vision
- Neurological conditions, such as multiple sclerosis, increased intracranial pressure, or headaches
- Autoimmune or inflammatory disorders, such as lupus or sarcoidosis
- An upcoming cataract surgery (to detect retinal conditions that might be hidden by the cloudy lens and to help with surgical planning, but sometimes imaging is taken after surgery if the visual outcome isn't what your doctor expected)
Some eye clinics and optometry offices also might offer routine retinal imaging tests to check for conditions before you have symptoms, McCannel says.
"Anybody can have a screening retinal image to look for any problems that might be there." It might not be as useful (and could lead to exams and testing that might not be necessary), but it sometimes helps eye doctors detect conditions or problems, he says.
How Is Retinal Imaging Done?
The doctor may dilate your eyes with special drops, which widen 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 your eye doctor takes digital pictures of your eyes. The images are uploaded to a computer so your doctor can look at them.
"To take pictures of the back of the eyes, there are two types of technologies," McCannel says. "The traditional flash photography takes good pictures of the back of the eye, but with a limited view. These cameras see only the part straight back from the pupil."
One method of retinal imaging (called standard fundus photography) uses a flash photo camera.
"Another kind of camera uses a laser beam that scans most of the back of the eye and generates a picture. This kind of picture sees so much more, but sometimes it makes it look like there is a problem when there is not," McCannel says.
A common method of retinal imaging that scans the back of the eye, called optical coherence tomography (OCT), lets your eye doctor look at 3D images of each layer of your retina.
If the doctor thinks you might have wet macular degeneration, you may 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.
Some eye doctors offer a type of angiogram where you don't need an injection of dye. This is called OCT angiography. It uses a laser beam to check the speed of blood cells floating throughout the eye, and based on their speed, it makes an image of the blood vessels through which they're moving, McCannel says.
The regular test takes five minutes. The fluorescein angiogram takes about 30 minutes, while OCT angiography is quicker.
What Happens After the Retinal Imaging Test?
If your eyes have been dilated, your vision will be blurry for about four hours. You'll be sensitive to sunlight and need to wear sunglasses . So, you need to have someone to drive you home.
If the fluorescein dye is used, don't wear soft contact lenses for about four hours so they don't get stained by the dye.
The images from the test should be ready immediately. Normally, your doctor will talk to you about them before you leave.
What Are the Benefits and Drawbacks of Retinal Imaging?
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.
The test has its limitations. It can't detect a disease where the retina is bleeding. Your doctor may also not be able to see problems on the outer edges of your retina.
Retinal imaging may be covered by your medical insurance (not your vision insurance) or Medicare. It depends on the terms of your policy as well as the reason you are having the test done.
If you get the routine type of retinal imaging that some eye clinics and optometry offices offer to people who don't have symptoms, just know that that sort of screening test can be a double-edged sword, McCannel says.
"Sometimes when people are asymptomatic, they have a serious condition that is discovered coincidentally, and that's good. And then sometimes, they have changes that look like a serious condition that can result in a number of visits with follow-ups and more expert practitioners, when maybe it wasn't really a problem to begin with," he says.
What Eye Conditions Can Retinal Imaging Detect?
Retinal imaging can help detect eye conditions such as:
- Diabetes-related macular edema, in which blood vessels leak fluid or grow out of control in the retina
- Diabetes-related retinopathy, in which blood vessels in the retina swell or leak
- Eye cancer (cancer that starts in the eye)
- Glaucoma, which damages the optic nerve that carries messages from the eyes to the brain
- Macular degeneration, a leading cause of vision loss that affects straight-ahead vision (or central vision)
- Macular hole, when an opening forms in the center of the retina (the macula) and makes central vision worse
- Macular pucker, in which wrinkles, creases, or bulges form on the macula
- Posterior uveitis, meaning inflammation that affects a layer on the inside of the back of the eye
- Retinal detachment, an emergency in which the retina pulls away from its usual position
- Retinal vein occlusion, in which a small blood vessel that transports blood away from your retina becomes blocked
Your eye doctor can recommend treatments for any of these conditions. They might also have you get follow-up retinal imaging over time to track your condition and check to see whether your treatment is working.
Retinal Imaging vs. Dilation: How Are They Different?
Retinal imaging takes a digital picture of the back of your eye. Dilation is a part of many eye exams in which your doctor widens your pupils using special eye drops.
Dilation allows more light to enter your eyes, which helps your doctor check for common eye conditions such as diabetes-related retinopathy, glaucoma, and macular degeneration.
While eye doctors often dilate the pupils for retinal imaging, more and more equipment can do the test without dilation, McCannel says. Still, eye doctors tend to get better images with dilation, he says.
How Do You Prepare for Retinal Imaging?
Usually, very little or no preparation is needed. But if you need to get your eyes dilated as part of your retinal imaging or eye exam, ask someone to drive you home. Bring sunglasses to wear after your appointment, as your eyes may be sensitive to light for a few hours.
Are There Any Risks or Side Effects of Retinal Imaging?
Not usually. If you get dilation as part of retinal imaging, you might have blurry vision for a few hours afterward, and light will bother your eyes. You also might get a headache.
If you get fluorescein angiography, there's a small chance your skin could become slightly yellowish for a short time. And your urine may look dark yellow or orange. Side effects like these tend to go away within a day.
The IV needle that goes into a vein in your arm may hurt briefly. Staying hydrated with a drink like water can make it easier for your doctor to place the needle, Fekrat says.
It's rare, but some people have an allergic reaction, such as hives or itching, to fluorescein. The risk of a severe allergic reaction, also called anaphylaxis, is very small.
How Often Should You Get Retinal Imaging?
Talk with your eye doctor about how often you should get retinal imaging. It depends on things such as whether you have a known eye condition and how often your doctor wants to check for changes in the condition or see how well the treatment is working.
How Much Does Retinal Imaging Cost and Is It Covered by Insurance?
"The cost of retinal imaging depends on what retinal image is obtained, where you live, and whether your insurance covers it and how much they cover. The cost may be within $50 per eye per image obtained," Fekrat says.
"Major health plans often do cover the cost of retinal imaging if there is a reason to obtain it. However, insurance companies may not pay for more than one imaging test on the same day if there is some overlap in the information that the testing provides to the doctor."
Can Retinal Imaging Detect Non-Eye Conditions?
Yes. Fekrat says that the test can help doctors detect some conditions that don't start in the eye, such as:
- Diabetes
- High blood pressure
- Certain blood cancers
- Certain metastatic cancers that have spread to other parts of the body
- Brain tumors
- Toxicities to some medications taken by mouth (caused by the buildup of the medicine in your bloodstream)
- Viral illnesses
Research is also being done to detect many other non-eye conditions, including heart disease and kidney disease, Fekrat says.
What's more, some researchers are looking into whether retinal imaging might someday be a reliable way to help doctors diagnose neurodegenerative conditions (such as Alzheimer's disease), which damage the nervous system over time.
"We are starting to understand that there are changes in the way the retina looks on high-powered imaging in neurodegenerative diseases," McCannel says. "This may be used for early diagnosis of some of these neurodegenerative conditions like Alzheimer's and Parkinson's disease in the future."
Takeaways
Retinal imaging takes digital pictures of the back of your eye, including the part that light and images hit, called the retina. This type of testing can help your eye doctor find or get more information about certain diseases you have and track the health of your eyes. Ask your eye doctor if you need retinal imaging and how often you should get it. If you have health insurance, check with your health plan to see if it covers the test.
Retinal Imaging FAQs
Why is retinal imaging recommended by eye doctors?
Your doctor may recommend retinal imaging to track your eye health if you have conditions such as diabetes, glaucoma, or macular degeneration. Some eye clinics and optometry offices also might offer routine retinal imaging tests to check for conditions before you have symptoms.
Is retinal imaging necessary or worth it?
If you have certain health conditions, your eye doctor might tell you that retinal imaging is necessary to keep tabs on your health or find out if a treatment is working. Retinal imaging that checks for certain conditions before you have symptoms comes with pros and cons. It could spot a serious condition, but in other cases, it could detect signs that are mistaken for a possible health problem, leading to doctor visits or more tests that possibly weren't needed, McCannel says.
Can I drive after retinal imaging?
If your doctor dilates your eyes as part of retinal imaging, you'll need to have someone drive you home after the exam. If you don't get dilation, you'll likely be able to drive afterward.
What machine is used for retinal imaging?
"There are many machines. Most often, it is a type of tabletop camera/imaging machine. They are all so different and often are not comparable between each other," Fekrat says. "The camera is often on a table and may have a tablet or desktop computer or tablet associated with it. Sometimes, the imaging camera may be handheld."
What is the difference between OCT and retinal imaging?
Optical coherence tomography (OCT) is one of the main methods of doing retinal imaging, while OCT scans your eyes and makes 3D images that let your doctor see each layer of your retina.
