Retinal degeneration is the progressive breakdown and death of light-sensing cells in the retina, the thin layer of tissue lining the back of your eye. It encompasses a wide range of conditions, from age-related macular degeneration (AMD) to inherited diseases like retinitis pigmentosa, and it remains one of the leading causes of irreversible blindness worldwide. In 2021, AMD alone caused vision impairment in roughly 8 million people globally, more than double the number affected in 1990.
What Happens Inside the Retina
Your retina contains specialized cells called photoreceptors, which convert light into electrical signals your brain interprets as vision. Two types do the heavy lifting: rods, which handle dim-light and peripheral vision, and cones, concentrated in the central retina (the macula), which provide sharp detail and color. Supporting these photoreceptors is a single layer of cells called the retinal pigment epithelium (RPE), which recycles visual pigments, removes waste, and delivers nutrients.
In retinal degeneration, photoreceptors, RPE cells, or the blood vessel layer beneath them (the choroid) deteriorate and eventually die. The specific trigger varies by disease, but several damaging processes show up repeatedly: oxidative stress that overwhelms the cell’s defenses, chronic low-grade inflammation, buildup of toxic waste products the RPE can no longer clear, and disrupted communication between blood vessels and nerve cells. Once enough cells are lost, the retina undergoes irreversible structural remodeling, and the vision those cells served cannot be recovered.
Major Types of Retinal Degeneration
Age-Related Macular Degeneration
AMD is the most common form of retinal degeneration in older adults. It comes in two varieties. Dry AMD, which accounts for the vast majority of cases, involves the slow accumulation of yellowish waste deposits called drusen beneath the RPE. Over time the RPE and overlying photoreceptors atrophy, creating patches of dead tissue known as geographic atrophy. Dry AMD behaves somewhat like a metabolic storage disease: cells gradually choke on debris they can no longer process, including non-degradable material called lipofuscin that builds up with age.
Wet AMD is less common but more abrupt. Immature blood vessels grow from the choroid into the retina, where they leak fluid and blood. This leakage can distort or destroy central vision within weeks. The RPE drives much of this process by releasing a growth signal (VEGF) in response to oxidative stress and inflammation, essentially calling for new blood vessels that end up causing more harm than help.
Retinitis Pigmentosa
Retinitis pigmentosa (RP) is a group of inherited conditions in which rod photoreceptors die first, followed later by cones. It typically begins with difficulty seeing in dim light (night blindness) and a gradual narrowing of peripheral vision, often described as tunnel vision. Central vision may be preserved for years or even decades before it, too, declines. RP can appear at any age, from childhood to middle adulthood, depending on the genetic variant involved.
The genetics behind RP are remarkably complex. Mutations in more than 50 different genes have been linked to the disease. It can be inherited in several patterns: autosomal dominant (20 to 25% of cases), autosomal recessive (15 to 20%), X-linked (10 to 15%), or as sporadic cases with no clear family history (about 30%). In the dominant form, a single gene called RHO, which encodes the light-sensing protein rhodopsin, accounts for 30 to 40% of cases. In X-linked RP, which tends to be more severe, roughly 70% of patients carry mutations in the RPGR gene.
Other Inherited Forms
Stargardt disease is the most common inherited macular degeneration, typically starting in childhood or adolescence and primarily affecting central vision. Late-onset retinal degeneration (L-ORD) is rarer, with symptoms usually beginning in the 40s or 50s as difficulty adapting to darkness. Vision in L-ORD can decline over one to two decades, sometimes progressing to complete blindness, though some patients retain islands of peripheral vision even at advanced stages.
Symptoms and How Vision Loss Progresses
Early retinal degeneration often produces no obvious symptoms. In AMD, the first sign may be slightly blurred central vision or a need for brighter light when reading. In RP and L-ORD, the earliest complaint is usually night blindness, a noticeable delay in adjusting when you walk into a dark room or drive at dusk.
As the disease advances, symptoms depend on which part of the retina is affected. Conditions that target the macula (AMD, Stargardt) erode central vision: straight lines appear wavy, faces become hard to recognize, and reading grows difficult. Conditions that begin in the peripheral retina (RP) shrink the visual field inward over years, eventually leaving only a small central window. In L-ORD, patients in their 30s and 40s may show normal results on standard eye charts even while subtle changes are already visible on imaging. Once atrophy reaches the central macula, however, visual acuity can drop rapidly.
The pace varies enormously. Non-neovascular AMD generally follows a slow, steady course beginning in the 60s. L-ORD compresses a similar degree of damage into one to two decades. Wet AMD can cause sudden, dramatic vision loss if untreated. And RP ranges from childhood-onset blindness to cases where functional vision persists well into middle age.
How Retinal Degeneration Is Diagnosed
An ophthalmologist typically starts with a dilated eye exam to look for drusen, pigment changes, or thinning of the retina. Optical coherence tomography (OCT) provides cross-sectional images of the retina’s layers, revealing atrophy, fluid accumulation, or subretinal deposits that may not be visible to the naked eye.
For inherited conditions, a full-field electroretinogram (ERG) is a key tool. It measures the electrical response of rod and cone photoreceptors across the entire retina, helping to determine how much function remains and whether the disease primarily affects rods, cones, or both. Genetic testing has become increasingly important for confirming a specific diagnosis, clarifying inheritance patterns so family members can understand their risk, and determining whether a patient is eligible for gene-targeted treatments.
Current Treatments
Wet AMD
Treatment for wet AMD centers on injections directly into the eye that block the growth signal driving abnormal blood vessel formation. Several of these drugs are FDA-approved, and they stabilize or improve vision in the vast majority of patients. Newer formulations allow longer intervals between injections, with some patients needing treatment only every three to four months rather than monthly.
Dry AMD
For years there was no treatment for dry AMD beyond antioxidant vitamin supplements (the AREDS2 formula), which reduce the risk of progression in people with intermediate disease. Two newer drugs that target the complement system, a part of the immune response that contributes to retinal cell death, have now been approved for geographic atrophy. These treatments slow the expansion of atrophic areas by up to 20%, but they do not restore lost vision.
Inherited Retinal Diseases
The first gene therapy for an inherited retinal degeneration was approved in 2017. It delivers a functional copy of the RPE65 gene directly to retinal cells in patients with a specific mutation that causes severe vision loss in childhood. Vitamin A and the omega-3 fatty acid DHA have shown modest reductions in the rate of progression for some RP patients, though the benefit is limited.
Experimental Approaches
Two areas of research are generating particular interest for patients whose photoreceptors are already too damaged for conventional treatment.
Optogenetic therapy aims to make surviving retinal cells light-sensitive by introducing genes for light-activated proteins. Multiple clinical trials are underway in patients with advanced RP. In an early case report, patients treated with one such protein (ChrimsonR) showed partial recovery of visual function, including the ability to detect and locate objects. At least five trials are currently testing different optogenetic approaches, and one has expanded into Stargardt disease.
Stem cell transplantation seeks to replace dead RPE cells with healthy ones grown from stem cells. In a phase 2a trial, patients who received lab-grown RPE cells showed signs that geographic atrophy progression may have slowed or even partially reversed, with a median improvement of about 7.6 letters on a standard eye chart at one year. Significant challenges remain: transplanted cells don’t always integrate properly into the existing tissue, and in AMD patients the aged membrane beneath the RPE can interfere with cell attachment. Researchers are exploring both scaffold-based patches and simple cell suspensions, each with its own tradeoffs in surgical complexity and long-term cell survival.