Retina Glossary: Key Terms for Your Eye Health
Anatomy of the Eye and Retina
The retina is a thin layer of light-sensitive nerve tissue that lines the back of the eye. It works like the film in a camera, capturing images and converting them into electrical signals. Those signals travel through the optic nerve to the brain, where they become the images you recognize.
The macula is a small area near the center of the retina. It is responsible for sharp central vision, the kind you use to read, drive, and recognize faces. The fovea is a tiny pit at the very center of the macula that provides the sharpest vision of all.
Because the macula handles detailed central vision, diseases that affect it can have a major impact on daily life even when side vision remains intact.
Photoreceptors are the cells in the retina that detect light. There are two types: rods and cones. The average human retina has 100 to many millions rods and 6 to many millions cones (AAO, Retinal Anatomy and Histology).
Rods handle night vision and peripheral vision. Cones are concentrated in the macula and handle color vision and fine detail.
The vitreous is a clear, gel-like substance that fills the inside of the eye. It helps the eye maintain its round shape and allows light to pass through to the retina.
As people age, the vitreous can shrink and pull away from the retina. This process is called a posterior vitreous detachment (PVD). While PVD is common and usually harmless, it can sometimes lead to a retinal tear.
The choroid is a layer of blood vessels beneath the retina. It supplies oxygen and nutrients to the outer retinal layers, especially the photoreceptors.
The retinal pigment epithelium (RPE) is a single layer of cells between the retina and the choroid. The RPE supports photoreceptors by recycling visual pigments and removing waste. Damage to the RPE plays a central role in age-related macular degeneration.
The optic nerve is a bundle of more than one million nerve fibers. It carries electrical signals from the retina to the brain and connects at the back of the eye at the optic disc.
The optic disc has no photoreceptors, creating a natural blind spot in each eye. Your brain fills in this gap so you do not notice it.
Common Retinal Conditions
Age-related macular degeneration (AMD) is a disease that damages the macula, causing gradual loss of central vision. It is the leading cause of vision loss in Americans over age 50. Approximately 19.8 million Americans have AMD (Retina Today, 2025).
AMD has two distinct forms that require different treatments. Dry AMD involves thinning of the macula and accumulation of deposits called drusen. Geographic atrophy is an advanced form of dry AMD where patches of retinal tissue waste away. Wet AMD involves abnormal blood vessel growth under the retina that leaks fluid or blood, causing rapid vision loss.
Diabetic retinopathy (DR) is a complication of diabetes that damages retinal blood vessels. Approximately 9.6 million Americans have DR (Retina Today, 2025). High blood sugar weakens retinal blood vessels over time, causing them to leak or close off.
Diabetic macular edema (DME) occurs when fluid from damaged vessels leaks into the macula, causing swelling. Proliferative diabetic retinopathy (PDR) is the advanced stage where fragile new blood vessels grow on the retinal surface and can bleed into the eye.
A retinal detachment happens when the retina separates from its supporting tissue. Without treatment, it can lead to severe, lasting vision loss. It is a medical emergency.
There are three types. A rhegmatogenous detachment starts with a tear or hole in the retina. A tractional detachment occurs when scar tissue pulls the retina away. An exudative detachment is caused by fluid collecting under the retina without a tear.
A retinal vein occlusion (RVO) occurs when a vein carrying blood away from the retina becomes blocked. This causes blood and fluid to leak into the retina, leading to swelling and vision loss.
A branch retinal vein occlusion (BRVO) affects a smaller branch vein. A central retinal vein occlusion (CRVO) affects the main vein and tends to cause more severe vision loss. Risk factors include high blood pressure, diabetes, and glaucoma.
A macular hole is a small break in the macula that causes blurred and distorted central vision. Most macular holes develop with age as the vitreous shrinks and pulls on the macula.
An epiretinal membrane (ERM), also called a macular pucker, is a thin sheet of scar tissue on the macula surface. It can wrinkle the macula, leading to distorted or blurry vision.
Diagnostic Tests and Imaging
A dilated eye exam is the most basic and important test for retinal health. Eye drops widen the pupil, allowing the retina, macula, and optic nerve to be seen in detail.
This exam can detect early signs of retinal disease before symptoms appear. Regular dilated exams are especially important for people with diabetes, high blood pressure, or a family history of retinal disease.
Optical coherence tomography (OCT) is a non-invasive imaging test that uses light waves to create cross-sectional images of the retina. It allows a retina specialist to see each layer and measure thickness.
OCT is essential for diagnosing and monitoring conditions like AMD, DME, macular holes, and epiretinal membranes.
Fluorescein angiography (FA) uses a special dye to examine blood flow in the retina. A yellow dye called fluorescein is injected into a vein in the arm, and a camera takes rapid photographs as the dye circulates.
This test identifies leaking blood vessels, areas of poor blood flow, and abnormal new vessel growth. It is commonly used for diabetic retinopathy, retinal vein occlusions, and wet AMD.
Fundus photography takes high-resolution color photographs of the retina. These images create a lasting record that helps track changes over time.
Fundus autofluorescence (FAF) detects the natural fluorescence of the RPE. It is particularly useful for monitoring geographic atrophy in dry AMD.
Ocular ultrasonography, or B-scan ultrasound, uses sound waves to create images of the inside of the eye. It is used when a dense cataract or vitreous hemorrhage (bleeding inside the eye) blocks the direct view of the retina.
Ultrasound can help detect retinal detachments, tumors, and other abnormalities. The test is painless and performed in the office.
Treatments and Procedures
Anti-VEGF injections are the most common treatment for wet AMD, DME, and retinal vein occlusions. VEGF stands for vascular endothelial growth factor, a protein that promotes abnormal blood vessel growth and fluid leakage. Anti-VEGF medications block this protein.
These medications are delivered as intravitreal injections (injections directly into the eye). Common anti-VEGF medications include:
- Eylea (aflibercept): given every 4 to 8 weeks after a loading phase
- Eylea HD (high-dose aflibercept): allows longer intervals, up to every 8 to 16 weeks after loading
- Lucentis (ranibizumab): the first anti-VEGF approved for eye use, given every 4 weeks
- Avastin (bevacizumab): FDA-approved for cancer but widely used off-label for retinal conditions, given every 4 to 6 weeks
- Vabysmo (faricimab): a bispecific antibody targeting two pathways, given every 4 to 16 weeks
Geographic atrophy (GA) is the advanced form of dry AMD. It is a separate condition from wet AMD and requires different treatment. Two complement inhibitors have been approved to slow GA progression:
- Syfovre (pegcetacoplan), a complement C3 inhibitor, given monthly or every other month
- Izervay (avacincaptad pegol), a complement C5 inhibitor, given monthly
These medications are given as intravitreal injections. They do not restore lost vision but may help slow further damage. They are not used for wet AMD. These complement inhibitor treatments are specifically for geographic atrophy associated with dry AMD and are different from wet AMD treatments.
Laser photocoagulation uses a focused beam of light to seal leaking blood vessels or destroy abnormal tissue. It is used for diabetic retinopathy, retinal vein occlusions, and retinal tears.
Panretinal photocoagulation (PRP) targets the peripheral retina to reduce abnormal vessel growth in proliferative diabetic retinopathy. Photodynamic therapy (PDT) uses a light-activated drug called verteporfin to treat certain abnormal blood vessels.
A vitrectomy is a surgery to remove the vitreous gel from inside the eye. The vitreous is replaced with saline, a gas bubble, or silicone oil to help the retina stay in place.
Vitrectomy treats retinal detachment, vitreous hemorrhage, macular hole, epiretinal membrane, and complications of diabetic retinopathy. Modern vitrectomy uses very small instruments and tiny incisions, allowing faster healing.
Several procedures can repair a retinal detachment. A scleral buckle places a silicone band around the eye to push the wall inward against the detached retina.
Pneumatic retinopexy injects a gas bubble to press the retina back into place. Cryopexy uses a freezing probe to seal a retinal tear, and laser retinopexy uses a laser for the same purpose. The approach depends on the location and extent of the detachment.
Steroid implants deliver anti-inflammatory medication inside the eye over an extended period. Ozurdex (dexamethasone implant) releases medication for several months. Iluvien (fluocinolone acetonide implant) can release medication for up to three years.
These implants treat conditions involving inflammation and swelling, such as DME and retinal vein occlusion. They are typically considered when anti-VEGF injections have not provided adequate results.
Understanding Your Risk Factors
Advanced age is the strongest risk factor for many retinal diseases, particularly AMD. The risk increases significantly after age 50. A family history of retinal disease also raises your risk.
If close family members have been diagnosed with AMD or other retinal conditions, mention this to your eye care provider. Earlier screening may be recommended.
Diabetes is the primary risk factor for diabetic retinopathy and DME. The longer a person has diabetes, the higher the risk. High blood pressure, high cholesterol, and smoking also raise the risk of retinal vascular diseases.
Managing these conditions through medication, diet, and exercise can help protect your retinal health.
High myopia (severe nearsightedness) stretches the eye and thins the retina. This increases the risk of retinal tears, retinal detachment, and myopic macular degeneration.
Previous eye surgery or eye trauma can also raise the risk of retinal problems. If you have had cataract surgery, LASIK, or any eye injury, let your retina specialist know.
When to See a Retina Specialist
Certain symptoms require immediate evaluation by a retina specialist or an emergency room visit. These may indicate a retinal tear, retinal detachment, or other serious condition that can cause lasting vision loss without prompt treatment:
- A sudden increase in floaters (small spots or cobwebs drifting in your vision)
- Flashes of light, especially in your peripheral vision
- A curtain or shadow spreading across your field of vision
- Sudden loss of vision in one eye
Not all retinal problems present as emergencies. Gradual changes also warrant evaluation. These include increasing difficulty with reading, distorted or wavy lines, trouble recognizing faces, and a dark or empty area in the center of your vision.
If you notice any of these changes, schedule an appointment with your eye care provider promptly. Early intervention provides the best chance of preserving your remaining vision.
Many retinal diseases cause no symptoms in their early stages. Regular dilated eye exams allow for early detection, when treatment is most effective. People with diabetes should have a dilated eye exam at least once a year.
Early treatment can often prevent or slow vision loss, even if it cannot fully restore vision that has been lost. Staying consistent with recommended exams is one of the most important steps you can take.
Questions and Answers
A retina specialist is an ophthalmologist who has completed one or two additional years of fellowship training focused on diseases and surgery of the retina and vitreous. General ophthalmologists and optometrists can diagnose many retinal conditions and provide referrals, but retina specialists handle complex diagnoses, intravitreal injections, and retinal surgeries.
Most patients report feeling pressure or mild discomfort rather than sharp pain. Numbing drops and sometimes a small injection of local anesthetic are applied before the procedure. The injection itself takes only a few seconds. Some soreness or a gritty feeling may last a day or two afterward.
Visit frequency depends on your specific condition and its severity. Patients receiving anti-VEGF injections may need visits every 4 to 16 weeks depending on their medication and response. Your retina specialist will create a personalized schedule based on your imaging results and overall eye health.
In most cases, retinal damage that has occurred cannot be fully reversed. However, many treatments can stop or slow further damage and help preserve remaining vision. In some conditions, such as DME, reducing swelling with treatment can improve vision. The goal of retinal care is to protect as much vision as possible.
Research into retinal treatments is very active. Scientists are developing longer-lasting anti-VEGF medications to reduce injection frequency. There are over 20 therapies under investigation for AMD, including 11 potential gene therapies (Retina Today, 2025). Other areas of research include optogenetics and retinal prostheses for people with severe retinal degeneration.