Macular Degeneration (AMD)

Macular Degeneration (AMD) is a multifactorial disease with no single cause. The pathogenesis—the biological mechanism by which the disease develops—involves aging, genetic susceptibility, oxidative stress, lipid accumulation, complement system dysregulation, and chronic low-grade inflammation, all converging on dysfunction and progressive loss of the photoreceptor, RPE, Bruch’s membrane, and choriocapillaris complex that supports central vision.

The foundation of AMD pathogenesis is the gradual failure of the functional unit that sustains central vision. The retinal pigment epithelium (RPE) is a single layer of cells that performs essential maintenance for the adjacent photoreceptors—recycling visual pigments, removing shed photoreceptor outer segments, maintaining the blood-retina barrier, and delivering oxygen and nutrients from the underlying choriocapillaris. With aging, RPE cells accumulate a toxic yellow-brown waste material called lipofuscin (including a particularly damaging component called A2E) from incomplete photoreceptor outer segment recycling. Their waste removal capacity declines, their mitochondria accumulate oxidative damage, and their ability to maintain Bruch’s membrane—the thin basement membrane they rest on—deteriorates. Bruch’s membrane thickens, stiffens from collagen crosslinking and advanced glycation end-products, and becomes less permeable, impairing the bidirectional exchange between RPE and the underlying choroidal blood supply. Choroidal blood flow itself decreases with age, reducing oxygen and nutrient delivery to the RPE. The net result is a metabolic stress state in which cellular waste products—lipoproteins, cholesterol, complement proteins, and other molecules—accumulate between the RPE and Bruch’s membrane, forming the drusen that are the cardinal hallmark of AMD.

Dysregulation of the alternative complement pathway—a branch of the immune system’s early defense mechanism—is now recognized as a primary molecular driver of AMD. Under normal conditions, regulatory proteins, including complement factor H (CFH), prevent complement activation from damaging the body’s own tissues. In AMD, genetic variants reduce the efficacy of these regulators, allowing the complement cascade to activate unchecked on the surfaces of the RPE and choriocapillaris. Overactivated complement generates C3a and C5a—pro-inflammatory proteins that recruit immune cells to the macula—and ultimately assembles the membrane attack complex (MAC/C5b-9) on choriocapillaris endothelial cells. MAC formation kills capillary endothelial cells, creating the choriocapillaris dropout that drives RPE hypoxia. Hypoxic RPE cells upregulate VEGF, which drives the abnormal blood vessel growth of wet AMD. The complement-targeted treatments approved for geographic atrophy in 2023 (pegcetacoplan and avacincaptad pegol) directly interrupt this cascade. Impaired complement regulation also disrupts RPE energy metabolism and lysosomal function, impairing the RPE’s ability to clear the waste products that accumulate in drusen.

The transition from dry to wet AMD is driven by vascular endothelial growth factor A (VEGFA) produced by oxygen-deprived RPE cells. VEGF is a powerful stimulator of new blood vessel growth and vascular permeability. In wet AMD, VEGF promotes the proliferation and migration of choroidal endothelial cells through breaks in Bruch’s membrane into the sub-RPE or subretinal space, forming the abnormal vessel network of choroidal neovascularization. Angiopoietin-2 (Ang-2) simultaneously destabilizes the walls of these new vessels, promoting leakage and inflammatory cell recruitment. The result is exudation—fluid, blood, and lipids spilling into and beneath the retina—that physically displaces and kills photoreceptors. All approved anti-VEGF drugs for wet AMD block this pathway.

The macula is uniquely vulnerable to oxidative damage. High photoreceptor metabolic rate, elevated oxygen tension from the adjacent choroid, decades of cumulative light exposure, and accumulating lipofuscin all generate reactive oxygen species (ROS) that damage RPE cell membranes, proteins, and deoxyribonucleic acid (DNA). Oxidative damage to Bruch’s membrane facilitates lipid accumulation and triggers complement activation—creating a feedforward cycle that accelerates AMD progression. This oxidative pathway is the biological rationale for the antioxidant components of the AREDS2 supplementation formula.

• Age: the single strongest risk factor for AMD. Risk approximately doubles with each decade after age 50. The National Eye Institute (NEI) and Centers for Disease Control and Prevention (CDC) identify age 55 as the key screening threshold. Approximately 22% of people over 70 and 34% of those over 80 are affected in at least one eye in Western countries.
• Race and ethnicity: AMD has the highest prevalence in Caucasian/white populations, driven largely by the high frequency of the CFH Y402H risk variant in European-ancestry individuals. Wet AMD in particular is overrepresented in this population. Black Americans have lower AMD prevalence overall, but when diagnosed often face similar rates of late-stage vision loss, partly related to patterns of underdiagnosis. Asian populations have lower AMD prevalence overall but higher rates of polypoidal choroidal vasculopathy (PCV), the nAMD variant that requires a different treatment approach.
• Female sex: Women have a slightly higher lifetime AMD risk, attributable partly to longer average lifespan and partly to hormonal factors.
• Family history: Having a first-degree relative (parent, sibling, or child) with AMD significantly elevates personal risk. AMD heritability is estimated at 45–70% in twin studies. Having late AMD in one eye greatly increases the risk of developing late AMD in the fellow eye.
• Genetic risk alleles: CFH Y402H homozygous and ARMS2 homozygous individuals each face approximately seven-fold elevated AMD risk. Combined high-risk genotype across both loci can confer more than a 50-fold elevated risk. Genetic testing is available but not required for routine clinical management.

• Cigarette smoking: the strongest modifiable risk factor. Active smokers have two to four times the risk of AMD compared to non-smokers, in a dose-dependent relationship. The risk acts through multiple mechanisms: oxidative stress, complement activation, and choroidal vasoconstriction. Risk decreases progressively after cessation and approaches non-smoker levels after approximately 20 years.
• Cardiovascular disease and hypertension: These are associated with AMD through shared vascular mechanisms, particularly impaired choroidal perfusion.
• High body mass index (BMI) and obesity: These are associated with increased AMD risk through metabolic inflammation.
• Diet low in antioxidants: Low dietary intake of lutein, zeaxanthin, omega-3 fatty acids, vitamin C, vitamin E, and zinc is associated with higher AMD risk. Adherence to a Mediterranean diet pattern—high in leafy green vegetables, fish, colorful fruits, nuts, and olive oil—is associated with significantly decreased AMD incidence. Higher fish and omega-3 intake is specifically associated with decreased risk of wet AMD.
• Low physical activity: A sedentary lifestyle is associated with higher AMD risk.
• Cumulative ultraviolet (UV) and blue light exposure: Phototoxic damage to RPE cells is biologically plausible; wearing UV-blocking sunglasses is reasonable, though causal proof is not definitive.

Early, presymptomatic detection of AMD is critically important because vision lost to AMD is irreversible once it occurs, and because the window for effective wet AMD treatment is time-sensitive—delays from symptom onset significantly worsen visual outcomes. Screening should prioritize individuals over age 55, those with a first-degree family history of AMD, and current or former smokers. The gold standard screening test is the comprehensive dilated eye examination, in which pupil-dilating drops allow direct visualization of the macula, drusen, RPE changes, and any evidence of fluid or neovascularization.

The NEI and American Academy of Ophthalmology (AAO) recommend the following examination frequency: adults aged 40 to 54 at lower risk every two to four years; adults aged 55 to 64 every one to three years, and adults aged 65 and older every one to two years (or annually with risk factors). Anyone with a family history of AMD or known AMD in one eye should follow their retinal specialist’s recommended schedule, which is typically annual or more frequent. Specific diagnostic tools used in AMD screening and monitoring include:

• Amsler grid: a simple home monitoring tool available from the NEI. The patient covers one eye and stares at a central dot on a grid of horizontal and vertical lines. Distorted, wavy, blurred, or missing lines (called metamorphopsia or scotoma) are warning signals of possible progression to late AMD. All patients with intermediate AMD should test each eye separately every day. Any new distortion should prompt urgent evaluation by an eye doctor—it may indicate conversion from dry to wet AMD, when treatment is most time-sensitive.
• Optical coherence tomography (OCT): The most important clinical imaging tool for AMD monitoring, it detects fluid above, below, and within the retina—including subretinal and intraretinal fluid that may be present before or alongside visual symptoms—and monitors RPE integrity, drusen morphology, and geographic atrophy area.
• Dilated fundoscopy: It gives direct visualization of drusen character and size, RPE changes, subretinal fluid, hemorrhage, and lipid exudates at every clinical visit.
• Fundus photography: This provides baseline photographic documentation of drusen pattern and RPE changes for longitudinal comparison over years.
• Visual acuity testing: This gives serial measurement with the Early Treatment Diabetic Retinopathy Study (ETDRS) or Snellen chart; loss of lines indicates functional progression.

Community-based and teleophthalmology screening programs are expanding access to AMD detection in underserved populations, and artificial intelligence (AI)-based retinal image analysis is emerging as an automated AMD screening tool with the potential to extend reach beyond traditional clinical settings.

AMD’s hallmark is that early and intermediate disease typically causes no symptoms—most patients do not notice any vision change until late AMD develops. This silent progression is why scheduled dilated eye examinations are so important. As the disease advances from early to intermediate to late stages, symptoms gradually emerge and worsen.

No symptoms. Disease is detected only on dilated eye examination, where drusen are visible. Central vision remains intact. There is no functional impairment at this stage.

Some patients remain entirely asymptomatic. Those with symptoms may notice mild central blurring, slightly reduced sharpness for fine-detail tasks, difficulty seeing clearly in dim lighting conditions, and an increased adaptation time when transitioning from brightly lit to darker environments.

• Metamorphopsia: Straight lines appear wavy, curved, bent, or distorted. This is the hallmark warning symptom of late AMD and should prompt urgent evaluation by an eye doctor. Doorframes, telephone poles, text on a page, and window frames that appear bent or wavy—especially in one eye—may indicate conversion from dry to wet AMD, when anti-VEGF treatment is most urgently needed.
• Central scotoma: A blurry, dark, or blank spot at or near the center of vision that gradually enlarges over time as more macular tissue is lost.
• Reduced visual acuity: Loss of the ability to read fine print, recognize faces, or perform close-up tasks with the affected eye.
• Reduced color perception: Colors appear less vivid, less saturated, or washed out.
• Difficulty with low-light vision: This is particularly prominent in geographic atrophy and in patients with subretinal drusenoid deposits; dark adaptation is impaired.
• Increased sensitivity to glare
• Difficulty reading: Letters may appear missing, blurry, or distorted; a line of text may appear to have gaps where letters have dropped out.
• Reduced contrast sensitivity: There may be difficulty distinguishing objects against similar-luminance backgrounds.
• Peripheral vision preserved: AMD does not cause total blindness; peripheral navigation is retained even in advanced disease, though central functional tasks become progressively impossible.

Wet AMD typically causes faster and more dramatic symptom onset than geographic atrophy—central vision distortion or loss can develop over days to weeks. A sudden, rapid change in central vision—new wavy lines, a new dark spot, or a sudden decline in reading vision—should be treated as an urgent symptom requiring same-day or next-day evaluation. Subretinal hemorrhage (bleeding beneath the retina) may cause a reddish-brown patch in central vision. Subretinal fluid from leaking CNV causes visual distortion and an elevation of the macula detectable on OCT before symptoms fully develop.

Geographic atrophy causes gradual, progressive central vision loss over months to years—characteristically slower than wet AMD. Reading becomes progressively more difficult as letters in the central field drop out or disappear. The scotoma first appears just outside the fovea (parafoveally) before eventually involving the foveal center; at that point, the most demanding central vision tasks become impossible with the affected eye.

AMD is diagnosed by a retinal specialist or ophthalmologist through a combination of fundoscopic examination and retinal imaging. No laboratory blood tests are required for diagnosis. Early and intermediate AMD are often discovered incidentally on routine dilated eye examination in asymptomatic individuals over age 55. Late dry AMD (geographic atrophy) is identified by the combination of progressive vision loss and characteristic atrophic lesions on imaging. Wet AMD typically presents with symptomatic sudden central distortion or blur and requires urgent evaluation. Genetic testing is available but not required for routine diagnosis; it is used for research, family counseling, and emerging genotype-stratified treatment decisions.

Dilated fundoscopy—direct visualization of the macula through the dilated pupil—identifies drusen size, character, and distribution; RPE abnormalities; subretinal fluid and hemorrhage; lipid exudates; fibrovascular scarring, and geographic atrophy. Drusen are graded by size: hard drusen (less than 63 micrometers, well-defined) indicate minimal risk, and soft drusen (greater than 125 micrometers, poorly defined borders) indicate substantially elevated risk. Drusen pattern and severity are scored using the AREDS Simplified Severity Scale (0 to 4 points based on drusen size and RPE abnormalities). Visual acuity is measured at every visit using the ETDRS chart (the gold standard for AMD clinical trials) or the standard Snellen chart.

Spectral-domain optical coherence tomography (SD-OCT) is the most widely used and clinically essential imaging tool for AMD. It provides high-resolution cross-sectional images of every retinal layer in micron-scale detail without dye injection or contact with the eye. OCT detects subretinal fluid (between the retina and RPE), intraretinal fluid (within the retinal layers), pigment epithelial detachment (PED—a dome-shaped elevation of the RPE from the underlying Bruch’s membrane), drusen morphology and volume, the integrity of the RPE band, and the outer segments of the photoreceptors. OCT is the primary tool for identifying wet AMD fluid before or alongside symptoms and for monitoring the treatment response to anti-VEGF injections. In geographic atrophy, OCT shows the progressive loss of the RPE band and the degeneration of photoreceptor outer segments in cross-section. Subretinal drusenoid deposits appear on OCT as hyperreflective material above the RPE layer. OCT angiography (OCT-A) provides noninvasive, dye-free visualization of retinal and choroidal blood flow, detecting the flow signals of choroidal neovascularization and distinguishing active CNV from inactive fibrotic lesions. OCT-A does not replace fluorescein angiography for assessing active leakage.

Fluorescein angiography (FA) involves an intravenous injection of sodium fluorescein dye followed by sequential retinal photographs documenting the dye’s passage through the retinal and choroidal circulation. FA is the gold standard for characterizing the type and activity of CNV in wet AMD. Classic CNV (well-defined, hyperfluorescent early with late leakage) and occult CNV (poorly defined, fibrovascular pigment epithelial detachment) are the two primary FA-defined patterns with implications for treatment and prognosis. Retinal angiomatous proliferation (RAP, also called type 3 CNV)—intraretinal neovascularization that grows downward to contact CNV—is a distinct pattern with its own clinical behavior. FA is essential for establishing treatment eligibility for photodynamic therapy and for treatment monitoring. Indocyanine green angiography (ICGA), using near-infrared excitation, provides superior visualization of the choroidal vasculature compared to fluorescein and is required for the diagnosis of polypoidal choroidal vasculopathy—the aneurysmal choroidal “polyps” of PCV are visible only on ICGA.

AMD is not curable—no treatment reverses existing retinal damage or restores vision that has already been lost. Treatment goals differ by disease stage. For early AMD, the approach is monitoring and lifestyle counseling. For intermediate AMD, AREDS2 supplementation reduces the risk of progression to late AMD. For wet AMD (neovascular AMD), intravitreal anti-VEGF injections preserve and, in many patients, improve vision by stopping the abnormal blood vessel growth and clearing the fluid causing damage. For geographic atrophy (dry late AMD), two complement inhibitor treatments approved in 2023 slow the rate of lesion growth, preserving more vision over time. Your retinal specialist will develop a treatment plan tailored to your specific AMD type, stage, and overall health. Early treatment initiation—especially for wet AMD—is critical: delays from symptom onset to first injection significantly worsen visual outcomes.

There is no FDA-approved pharmacologic treatment for early AMD. Management consists of annual dilated eye examinations, patient education about warning symptoms, daily Amsler grid home monitoring for any sign of metamorphopsia, and comprehensive lifestyle counseling: smoking cessation, Mediterranean diet adherence, regular aerobic exercise, UV protection, and cardiovascular risk factor management. These steps reduce the risk of progression to more advanced stages and address the modifiable contributors to AMD pathogenesis.

The Age-Related Eye Disease Study 2 (AREDS2)—a large, multicenter, NIH)-funded randomized controlled trial—established the evidence base for nutritional supplementation in intermediate AMD. The AREDS2 formula is recommended for patients with intermediate AMD in one or both eyes, or late AMD in one eye. It reduces the risk of progression to late AMD by approximately 25% over 5 to 10 years of use. The formula contains vitamin C (500 mg), vitamin E (400 IU), lutein (10 mg), zeaxanthin (2 mg), zinc oxide (80 mg, or 25 mg per updated analysis), and cupric oxide (2 mg to prevent zinc-induced copper deficiency). Importantly, the AREDS2 formula uses lutein and zeaxanthin in place of the beta-carotene that was in the original AREDS formula—beta-carotene was found to nearly double the risk of lung cancer in smokers and former smokers and should not be taken by this group. AREDS2 supplementation is not indicated for early AMD, where no benefit has been demonstrated, and is not a treatment for late AMD—it does not reverse existing damage.

Anti-VEGF therapy is the standard of care for neovascular (wet) AMD and has transformed the prognosis of this previously devastating condition. All anti-VEGF agents are administered by intravitreal injection—a brief, well-tolerated in-office procedure in which the drug is injected directly into the vitreous cavity through a small-gauge needle under topical anesthetic, allowing the drug to reach therapeutic concentrations within the eye. The general injection procedure risks common to all agents include a small risk of endophthalmitis (intraocular infection, less than 0.1% per injection), retinal detachment, transient intraocular pressure (IOP) spike, and subconjunctival hemorrhage at the injection site.

• Ranibizumab (Lucentis®, FDA-approved 2006): a recombinant humanized antibody fragment (Fab) targeting all isoforms of VEGF-A, designed specifically for ophthalmic use. Given as an intravitreal injection of 0.5 mg monthly during an initial loading phase, then on a pro re nata (as needed) or treat-and-extend schedule. The pivotal ANCHOR and MARINA clinical trials demonstrated that ranibizumab prevented vision loss in more than 90% of wet AMD patients and resulted in 30–40% of patients gaining 15 or more letters of vision. Susvimo®—a ranibizumab port delivery system implant surgically inserted into the vitreous that can be refilled in the clinic every six months—received FDA approval in 2021 for patients already responsive to ranibizumab injections, substantially reducing the injection frequency burden.
• Bevacizumab (Avastin®, off-label): a full-length humanized monoclonal antibody against all VEGF-A isoforms. FDA-approved for colorectal cancer but widely used off-label for wet AMD because of its substantially lower cost. The NEI’s Comparison of AMD Treatments Trials (CATT, 2011) demonstrated equivalent visual acuity outcomes to ranibizumab over two years, making bevacizumab the most cost-effective anti-VEGF option. It is prepared by compounding pharmacies and administered at a 1.25 mg dose. The same-treatment-effect at lower cost makes it an important access option, particularly in resource-limited settings.
• Aflibercept (Eylea®, FDA-approved 2011; Eylea HD FDA-approved 2023): a VEGF trap fusion protein that binds all isoforms of VEGF-A, VEGF-B, and placental growth factor (PlGF) with higher binding affinity than ranibizumab or bevacizumab. The standard 2 mg dose is given monthly for three loading doses, then every two months—fewer injections than ranibizumab while maintaining equivalent efficacy, established in the VIEW 1 and VIEW 2 clinical trials. High-dose aflibercept 8 mg (Eylea® HD) extends treatment intervals to every 12 to 16 weeks after loading doses for many patients, further reducing the injection burden.
• Faricimab (Vabysmo®, FDA-approved January 2022): the first bispecific antibody approved for an ophthalmic indication. Faricimab simultaneously neutralizes both VEGF-A and angiopoietin-2 (Ang-2)—a molecule that destabilizes vessel walls and promotes leakage. By blocking both targets, faricimab addresses both abnormal vessel growth (via VEGF inhibition) and vascular instability (via Ang-2 inhibition and Tie2 receptor activation). The TENAYA and LUCERNE Phase III trials demonstrated non-inferiority to aflibercept at one year, and up to 45% of patients qualified for every-16-week dosing at one year—the longest approved treatment interval of any anti-VEGF agent for wet AMD.
• Brolucizumab (Beovu, FDA-approved 2019): a single-chain antibody fragment against VEGF-A that achieves a higher molar concentration per injection than larger molecules, allowing up to every-12-week dosing intervals in many patients. Important safety note: brolucizumab carries a higher incidence of intraocular inflammation (approximately 2.1%), retinal vasculitis, and retinal artery occlusion compared to aflibercept, identified in clinical trials and post-marketing surveillance. It is generally used in refractory cases rather than as a first-line agent.

In February 2023, pegcetacoplan (Syfovre®) became the first FDA-approved treatment for geographic atrophy secondary to AMD—the first approved therapy for any form of dry AMD. A second complement inhibitor, avacincaptad pegol (Izervay®), received FDA approval in August 2023. Both are administered by intravitreal injection and work by interrupting the overactivated complement cascade that drives RPE cell death and GA lesion expansion. Neither treatment restores vision that has already been lost, but both slow the rate at which the GA lesion grows and additional retinal tissue is destroyed.

• Pegcetacoplan (Syfovre®): targets complement factor C3, the central intersection point of all three complement activation pathways. By inhibiting C3, pegcetacoplan blocks the generation of all downstream complement effectors, including C3a, C5a, and the membrane attack complex. Administered by intravitreal injection of 15 mg monthly or every other month. The OAK and DERBY Phase III trials demonstrated approximately 36% reduction in GA lesion growth rate with monthly dosing versus sham injection at 18 to 24 months—with the greatest benefit emerging over time. An important safety consideration: pegcetacoplan is associated with a small increase in the risk of choroidal neovascularization (wet AMD conversion) in treated eyes—approximately 2–3% higher than sham. All patients receiving pegcetacoplan require monitoring for new CNV development, and any new symptoms of wet AMD during treatment should be evaluated promptly.
• Avacincaptad pegol (Izervay®): a ribonucleic acid (RNA) aptamer targeting complement factor C5, the step immediately before MAC assembly, blocking both C5a formation and MAC-mediated choriocapillaris endothelial cell death. Administered as a monthly intravitreal injection of 2 mg. The GATHER1 and GATHER2 Phase III trials demonstrated approximately 27–29% reduction in GA lesion growth rate versus sham at 12 months. The same risk of wet AMD conversion as pegcetacoplan applies; monitoring for nAMD development is required.

Photodynamic therapy (PDT) with verteporfin (Visudyne®) uses a two-step process: an intravenous infusion of the photosensitizing drug verteporfin (which accumulates preferentially in actively proliferating neovascular endothelial cells), followed within 15 minutes by illumination of the CNV lesion with a 689 nm nonthermal laser for 83 seconds. The activated verteporfin generates reactive oxygen species that selectively occlude the CNV blood vessels with minimal damage to the overlying retina. PDT was the first approved treatment for wet AMD (2000) but has been largely replaced by anti-VEGF therapy as first-line treatment. Its current primary indications are polypoidal choroidal vasculopathy (where PDT combined with anti-VEGF is the preferred treatment approach), selected occult CNV cases refractory to anti-VEGF monotherapy, and central serous chorioretinopathy (where half-dose verteporfin PDT is now the primary treatment). Patients must avoid direct sunlight and bright indoor lighting for 48 hours after verteporfin infusion due to photosensitivity.

Surgical options for AMD are limited and generally reserved for specific complications. Vitrectomy with submacular hemorrhage evacuation addresses large submacular bleeds associated with wet AMD, improving the ability to continue anti-VEGF treatment, though it does not reliably restore vision independently. Submacular surgery (surgical removal of CNV membranes) and macular translocation surgery (moving the fovea away from the CNV) are largely historical procedures that have been replaced by anti-VEGF therapy. Retinal pigment epithelium transplantation using cells derived from induced pluripotent stem cells (iPSC) or embryonic stem cells (ESC) is currently under investigation in NIH-funded Phase I and II clinical trials for geographic atrophy; no such treatment is FDA-approved as of 2026, but this is an active area of research.