Retina Glossary: Understanding Key Eye Terms
Anatomy of the Eye and Retina
Before exploring what can go wrong with the retina, it helps to understand how the eye is built and what each part does.
The retina is a thin layer of light-sensitive nerve tissue that lines the inside back wall of the eye. It functions similarly to the film in a camera. When light enters the eye, the retina captures the image and converts it into electrical signals. Those signals travel through the optic nerve to the brain, where they are processed into the images you see.
Because the retina does so much of the visual work, damage to even a small area can significantly affect your sight.
The macula is a small, specialized area near the center of the retina. It is responsible for sharp, detailed central vision, the kind you use for reading, driving, and recognizing faces.
The fovea is a tiny pit at the very center of the macula that delivers 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 (peripheral) vision remains intact.
Photoreceptors are specialized cells in the retina that detect light. There are two types: rods and cones, and each plays a different role in how we see.
Rods are responsible for night vision and peripheral vision. Cones are concentrated in the macula and handle color vision and fine detail. When photoreceptors are lost or damaged by disease, vision loss can occur in ways that reflect which type was affected.
The vitreous is the clear, gel-like substance that fills the large central chamber of the eye. It helps the eye maintain its round shape and allows light to pass cleanly through to the retina.
As people age, the vitreous slowly shrinks and may pull away from the retina. This is called a posterior vitreous detachment, or PVD. PVD is common and usually harmless, but it can sometimes tug on the retina and create a tear. This is why a sudden increase in floaters or flashes of light should always be evaluated promptly.
The choroid is a dense layer of blood vessels beneath the retina. It supplies oxygen and nutrients to the outer retinal layers, particularly the photoreceptors, which have high energy demands.
Directly between the retina and the choroid sits the retinal pigment epithelium, or RPE. The RPE is a single layer of cells that recycles the visual pigments photoreceptors need to detect light and clears away cellular waste products. Damage to the RPE is a central feature of several retinal diseases, including age-related macular degeneration.
The optic nerve is a thick bundle of more than one million nerve fibers. It connects the retina to the brain and carries the electrical signals that become vision. The point where the optic nerve meets the retina is called the optic disc.
Because the optic disc has no photoreceptors, each eye has a natural blind spot at that location. The brain compensates for this automatically, so most people are entirely unaware of it.
Common Retinal Conditions
Retinal diseases vary widely in their causes, symptoms, and treatments. Knowing the names of these conditions and what they involve can make a diagnosis easier to process and discuss with your care team.
Age-related macular degeneration, commonly called AMD, is a disease that damages the macula and causes gradual central vision loss. It is the leading cause of vision loss in adults over age 50 in the United States.
AMD exists in two main forms. Dry AMD involves the slow thinning of the macula and the buildup of small deposits called drusen beneath the retina. Geographic atrophy is the advanced form of dry AMD, in which patches of retinal tissue gradually waste away. Wet AMD is a more aggressive form in which abnormal blood vessels grow under the retina and leak fluid or blood, often causing faster vision loss. Dry and wet AMD are distinct conditions that require different treatments.
Diabetic retinopathy (DR) is a complication of diabetes in which high blood sugar gradually weakens and damages the small blood vessels supplying the retina. Over time, these vessels can leak, become blocked, or trigger the growth of new, fragile vessels on the retinal surface.
Diabetic macular edema (DME) occurs when fluid from damaged blood vessels leaks into the macula, causing swelling that blurs central vision. Proliferative diabetic retinopathy (PDR) is an advanced stage in which new blood vessels grow across the retinal surface and may bleed into the interior of the eye, a condition called vitreous hemorrhage. Both are serious and require timely treatment.
A retinal detachment occurs when the retina separates from the underlying layer of tissue that supports and nourishes it. Without prompt treatment, a detachment can cause severe and permanent vision loss. It is a medical emergency.
There are three main types. A rhegmatogenous detachment begins with a tear or break in the retina, allowing fluid to seep underneath and lift it away. A tractional detachment occurs when scar tissue on the retinal surface pulls the retina away from its support layer, which is most common in advanced diabetic retinopathy. An exudative detachment is caused by fluid accumulating under the retina without a tear, often due to inflammation or an intraocular tumor.
A retinal vein occlusion (RVO) occurs when one of the veins that carries blood away from the retina becomes blocked. The blockage causes blood and fluid to back up and leak into the retina, leading to swelling and vision loss.
A branch retinal vein occlusion (BRVO) affects a smaller vein in one section of the retina. A central retinal vein occlusion (CRVO) affects the main vein and typically causes more widespread vision loss. Common risk factors include high blood pressure, diabetes, high cholesterol, and glaucoma, which refers to increased pressure inside the eye.
A macular hole is a small break or opening in the center of the macula. It typically causes blurred, distorted, or missing central vision and most often develops as a result of age-related changes in the vitreous that gradually pull on the macula over time.
An epiretinal membrane (ERM), also known as a macular pucker, is a thin layer of scar tissue that forms on the surface of the macula. As this membrane contracts, it can wrinkle or pucker the underlying retinal tissue, causing distorted or blurry vision. Both conditions are diagnosed with imaging tests and may be candidates for surgical treatment.
Diagnostic Tests and Imaging
Retina specialists rely on a range of tests to examine the retina in detail, monitor disease over time, and guide treatment decisions. Here is what each test involves and why it matters.
A dilated eye exam is the most fundamental tool for evaluating retinal health. Eye drops are placed in the eye to widen, or dilate, the pupil, which gives the retina specialist a much broader and clearer view of the retina, macula, and optic nerve.
This exam can detect early signs of retinal disease before symptoms develop, which is especially valuable because many retinal conditions cause no noticeable changes in the early stages. People with diabetes, high blood pressure, or a family history of retinal disease should have dilated exams on a regular schedule as recommended by their care team.
Optical coherence tomography, known as OCT, is a non-invasive imaging test that uses light waves to create detailed, cross-sectional images of the retinal layers. It does not require injections or dye and takes only a few minutes to perform in the office.
OCT allows a retina specialist to visualize each individual layer of the retina and measure its thickness precisely. It is essential for diagnosing and monitoring conditions such as AMD, DME, macular holes, and epiretinal membranes. OCT angiography (OCTA) is an advanced variation that maps blood flow in the retinal vessels without the need for injected dye.
Fluorescein angiography (FA) is an imaging test that evaluates blood flow in the retina and the choroid beneath it. A yellow dye called fluorescein is injected into a vein in the arm, and as the dye circulates through the eye's blood vessels, a specialized camera captures a rapid sequence of photographs.
This test is particularly effective at identifying leaking blood vessels, areas with poor circulation, and abnormal new vessel growth. It is commonly used in the evaluation and management of diabetic retinopathy, retinal vein occlusions, and wet AMD.
Fundus photography produces high-resolution color images of the retina. These photographs create a detailed visual record that allows the care team to compare images over months or years and detect subtle changes.
Fundus autofluorescence (FAF) is a related imaging technique that detects the natural fluorescence emitted by the retinal pigment epithelium without requiring any dye. FAF is particularly useful for monitoring the progression of geographic atrophy in dry AMD, as it clearly shows areas where the RPE has been lost.
Ocular ultrasonography, also called B-scan ultrasound, uses sound waves to create images of the inside of the eye. It is used when a dense cataract, vitreous hemorrhage, or other opacity prevents a direct optical view of the retina.
Ultrasound can detect retinal detachments, intraocular tumors, and other structural abnormalities even when standard imaging is not possible. The test is painless and is performed in the office.
Treatments and Procedures
Many retinal conditions can be treated effectively, especially when detected early. The right treatment depends on the specific diagnosis, disease severity, and individual patient factors, and is always determined by your retina specialist.
Anti-VEGF injections are among the most widely used treatments in retina care. VEGF stands for vascular endothelial growth factor, a protein that drives abnormal blood vessel growth and fluid leakage in conditions such as wet AMD, DME, and retinal vein occlusion. Anti-VEGF medications work by blocking this protein to reduce leakage and slow disease progression.
These medications are delivered directly into the eye through an intravitreal injection, meaning an injection into the vitreous cavity. The most commonly used anti-VEGF agents include the following:
- Eylea (aflibercept): typically given every four to eight weeks after an initial loading phase
- Eylea HD (high-dose aflibercept): designed to allow longer treatment intervals, potentially every eight to sixteen weeks after loading
- Lucentis (ranibizumab): the first anti-VEGF medication approved specifically for eye conditions, often given every four weeks
- Avastin (bevacizumab): FDA-approved for cancer treatment and widely used off-label for retinal conditions, typically given every four to six weeks
- Vabysmo (faricimab): a newer bispecific antibody that targets two pathways involved in abnormal vessel growth and leakage, given every four to sixteen weeks
Your retina specialist will recommend the medication and schedule best suited to your diagnosis and how your eye responds to treatment.
Geographic atrophy (GA) is the advanced form of dry AMD and a distinct condition from wet AMD, requiring its own specifically approved treatments. Two complement inhibitors have been approved by the FDA to help slow the progression of GA.
- Syfovre (pegcetacoplan): a complement C3 inhibitor given as a monthly or every-other-month intravitreal injection
- Izervay (avacincaptad pegol): a complement C5 inhibitor given as a monthly intravitreal injection
These medications are designed to slow the rate at which retinal tissue is lost. They do not restore vision that has already been affected, and they are not used for wet AMD. As with all treatments, the decision to begin therapy is made in partnership with your retina specialist based on your imaging and overall health history.
Laser therapy uses focused light energy to treat several retinal conditions. The specific type of laser used depends on the condition being treated and its severity.
- Laser photocoagulation seals leaking blood vessels or destroys abnormal tissue and is used for diabetic retinopathy, retinal vein occlusions, and retinal tears
- Panretinal photocoagulation (PRP) applies laser to the peripheral retina to reduce abnormal vessel growth in proliferative diabetic retinopathy
- Photodynamic therapy (PDT) uses a light-activated drug called verteporfin to target and close certain types of abnormal blood vessels
- Non-thermal transscleral diode laser is an additional modality used in select clinical situations
Your retina specialist will explain which approach is most appropriate for your condition and what to expect during and after treatment.
A vitrectomy is a surgical procedure in which the vitreous gel is carefully removed from inside the eye. Once removed, the vitreous is replaced with a saline solution, a gas bubble, or silicone oil to support the retina and maintain the shape of the eye during healing.
Vitrectomy is used to treat retinal detachment, vitreous hemorrhage, macular holes, epiretinal membranes, and complications of advanced diabetic retinopathy. Modern vitrectomy techniques use very small instruments and tiny incisions, which supports a faster and more comfortable recovery compared to older surgical approaches.
The approach to repairing a retinal detachment depends on the type, location, and extent of the separation. Several procedures may be used, sometimes in combination, and the choice is guided by your retina specialist.
- Scleral buckle: a flexible silicone band placed around the outside of the eye to gently push the eye wall inward against the detached retina
- Pneumatic retinopexy: a small gas bubble injected into the eye to press the retina back into its correct position
- Cryopexy: a freezing probe used to seal a retinal tear by creating a controlled scar around it
- Laser retinopexy: laser energy used to seal a retinal tear in a similar way to cryopexy
Vitrectomy may also be performed as part of detachment repair, particularly for complex cases. Your care team will determine the safest and most effective combination of techniques for your specific situation.
Steroid-based treatments deliver anti-inflammatory medication inside the eye over an extended period. They are most often considered for diabetic macular edema, retinal vein occlusion, and uveitis (inflammation inside the eye) when anti-VEGF therapy alone has not provided adequate results.
- Ozurdex (dexamethasone implant): a small, biodegradable implant that releases medication for several months
- Iluvien (fluocinolone acetonide implant): a longer-acting implant that can release medication for up to three years
Steroid injections without an implant may also be appropriate in some situations. As with all treatments, the choice and timing are guided by your retina specialist based on your individual response and overall eye health.
Understanding Your Risk Factors
Some risk factors for retinal disease cannot be changed, but many can be managed. Understanding your personal risk helps you and your care team make proactive decisions about monitoring and prevention.
Advanced age is the single strongest risk factor for many retinal diseases, particularly AMD. The risk increases notably after age 50 and continues to rise with each passing decade. A family history of AMD or other retinal conditions also raises your individual risk.
If close relatives have been diagnosed with a retinal disease, let your eye care provider know. Earlier or more frequent screening may be recommended, even before you notice any change in your vision.
Diabetes is the primary risk factor for diabetic retinopathy and diabetic macular edema. The longer a person has lived with diabetes, and the less controlled blood sugar levels are, the higher the risk that retinal blood vessels will be affected. High blood pressure, elevated cholesterol, and smoking also increase the risk of retinal vascular disease.
Managing these underlying conditions through medication, diet, and consistent medical care is one of the most effective ways to protect your retinal health over time.
High myopia, also called severe nearsightedness, causes the eye to grow longer than normal, which stretches and thins the retinal tissue. This increases the risk of retinal tears, retinal detachment, and a condition called myopic macular degeneration.
Previous eye surgery, such as cataract removal or LASIK, and any history of eye injury can also raise the risk of retinal complications. If any of these apply to you, be sure to share that information with your retina specialist so your care can be appropriately tailored.
When to See a Retina Specialist
Knowing when to seek care can make a meaningful difference in the outcome of a retinal problem. Some situations call for immediate attention, while others should be addressed promptly but not necessarily as emergencies.
The following symptoms may indicate a retinal tear, retinal detachment, or another serious condition. They require immediate evaluation at a retina specialist's office or, if unavailable, at an emergency room. Do not wait to schedule a routine appointment if you experience any of these:
- A sudden increase in floaters (dark spots, strings, or cobwebs drifting through your vision)
- Flashes of light, especially in your peripheral (side) vision
- A shadow, curtain, or veil spreading across any part of your visual field
- Sudden loss of vision in one eye
Not all retinal problems develop suddenly. Gradual vision changes should also be evaluated by a care provider, even if they seem minor at first. These include increasing difficulty reading, straight lines appearing wavy or distorted, trouble recognizing faces, and a dim or empty area developing in the center of your vision.
Scheduling an appointment promptly when you notice gradual changes gives your care team the best opportunity to identify the cause and begin treatment when it is most effective.
Many retinal diseases produce no symptoms in their early stages, which makes regular dilated eye exams the most reliable way to catch these conditions before significant vision loss occurs. People with diabetes should have a dilated eye exam at least once a year and more frequently if their care team advises it.
Early detection typically means more treatment options and a better chance of preserving useful vision. Staying consistent with your scheduled exams is one of the most important steps you can take for your long-term visual health.
Frequently Asked Questions
These answers address questions we hear often from patients who are new to retina care or adjusting to a diagnosis. If you have a question not covered here, our care team is always happy to help.
A retina specialist is a medical doctor who completed four years of medical school, internship, three years of ophthalmology residency, and then one to two additional years of fellowship training focused specifically on diseases and surgery of the retina and vitreous. This additional training is what enables a retina specialist to perform intravitreal injections and complex retinal surgeries. Your optometrist or general ophthalmologist plays an important role in detecting early signs of retinal disease and coordinating referrals, but once a retinal condition is confirmed, a specialist is typically needed for ongoing management. Patients may also self-refer to a retina specialist if they are experiencing symptoms or have concerns about their retinal health.
After dilation, your vision may be blurry and your eyes more sensitive to bright light for several hours, which can make driving uncomfortable or unsafe for some patients. We recommend arranging a ride to and from your appointment when possible, particularly for a first-time dilation or if you know your light sensitivity tends to be prolonged. Wearing sunglasses can help manage light sensitivity during this period. If you are unsure whether you are safe to drive after your visit, wait until your vision returns fully to normal before getting behind the wheel.
For conditions managed with regular anti-VEGF injections, staying close to the recommended schedule matters. Missing or delaying an appointment can allow fluid to return or worsen, which may affect your vision. If you need to reschedule, contact our office as soon as possible so we can find the earliest available time. Your retina specialist will review your imaging at the rescheduled visit to assess whether any adjustment to your treatment plan is needed. Please reach out rather than simply skipping an appointment, even if your vision feels stable.
In most cases, retinal tissue that has been permanently lost cannot be fully restored. However, not all treatment goals involve restoration. For many conditions, such as wet AMD or diabetic macular edema, reducing fluid and stopping abnormal vessel activity can stabilize vision and, in some cases, allow for meaningful improvement. How much improvement is possible depends on how much damage occurred before treatment began and how the individual retina responds over time. This is why early diagnosis and consistent follow-up care have such a significant impact on outcomes.
A thorough first visit typically includes a review of your medical and eye health history, a dilated eye exam, and one or more imaging tests. To make the appointment as efficient as possible, bring a complete list of your current medications including dosages, any prior eye records or imaging you have access to, and your glasses or contact lens prescription if applicable. If you have a systemic condition such as diabetes or high blood pressure, it helps to have recent lab results available. The visit may take longer than a routine eye exam, sometimes up to two hours, particularly if multiple tests are needed, so plan accordingly.
Research into retinal diseases is very active, and clinical research programs offer some patients access to investigational approaches that are not yet broadly available. Areas of ongoing investigation include longer-acting anti-VEGF therapies intended to reduce injection frequency, gene therapy approaches for inherited and acquired retinal conditions, and new treatments for geographic atrophy and other forms of macular disease. Whether a research opportunity is appropriate for any individual depends on their diagnosis, disease stage, and other health factors. If you are curious about whether a clinical research opportunity may be relevant to your care, your retina specialist is the right person to ask.
Expert Retina Care Across Connecticut
At New England Retina Associates, our fellowship-trained vitreoretinal surgeons provide expert, compassionate care for the full range of retinal conditions across Connecticut. We welcome both self-referred patients and those referred by their eye care providers, and we are committed to making sure every patient understands their diagnosis and feels supported at every stage of their care. We invite you to contact our practice to schedule an evaluation and take an important step toward protecting your long-term vision.