Age-Related Macular Degeneration

• Retinal pigment epithelium dysfunction and drusen formation: The RPE normally maintains the outer retina through phagocytosis of photoreceptor outer segments and delivery of nutrients from the choroid. With aging, lysosomal dysfunction impairs complete degradation of ingested material, leading to accumulation of lipofuscin and oxidized lipids. These residual debris, along with complement components (C3, C5b-9), apolipoprotein B, and amyloid-beta, aggregate as drusen—the pathologic hallmark of AMD. Drusen represent thickening of Bruch's membrane and contribute to RPE detachment. The complement cascade becomes hyperactivated in AMD (particularly the alternative pathway), driven by chronic local inflammation from pattern recognition receptors responding to drusen components and oxidized lipids. This perpetuates a cycle of RPE damage and photoreceptor loss in dry AMD.

• Oxidative stress and mitochondrial dysfunction: The retina, particularly the photoreceptor-rich macula, has exceptionally high metabolic demands and oxygen consumption, making it uniquely vulnerable to reactive oxygen species (ROS) generation. Lipofuscin and other oxidative products within RPE cells generate additional ROS through electron transport chain dysfunction. Antioxidant defenses (superoxide dismutase, catalase, glutathione peroxidase) decline with age, allowing accumulation of oxidized lipoproteins and protein aggregates. Mitochondrial DNA mutations increase with age in RPE cells, further compromising antioxidant capacity and energy production. This oxidative environment damages photoreceptor membranes through lipid peroxidation and impairs RPE tight junctions, compromising the blood-retinal barrier.

• Choroidal neovascularization in exudative AMD: In wet AMD, pathologic neovascular endothelial growth factor (VEGF)-mediated angiogenesis occurs beneath the retina. RPE cells and infiltrating inflammatory cells (macrophages) respond to hypoxia and ischemia by upregulating vascular endothelial growth factor (VEGF)-A, the principal angiogenic driver. VEGF-A binds to VEGFR2 on endothelial cells, triggering sprouting angiogenesis and destabilizing the choroidal vasculature. These immature, permeable neovessels leak fluid and blood into the subretinal space, causing rapid photoreceptor damage through mechanical disruption and ischemia. Additionally, angiopoietin dysregulation, inflammatory cytokine accumulation (TNF-α, IL-6), and loss of pericyte support contribute to the pathologic angiogenic response. Choroidal neovascularization (CNV) can be classified histologically as occult (hidden beneath RPE) or classic (visible on angiography), each with different prognoses.

• Genetic susceptibility and immune dysregulation: Genome-wide association studies have identified >30 genetic loci associated with AMD risk, with the strongest signals in complement factor H (CFH), complement component 3 (C3), and complement factor B (CFB)—all components of the alternative complement pathway. The CFH Y402H polymorphism increases complement dysregulation and AMD risk approximately 2-3 fold. Additional susceptibility loci include ARMS2/HTRA1 (age-related maculopathy susceptibility protein), APOE (apolipoprotein E), and ABCA4 genes. These genetic factors likely modify the threshold for developing AMD when combined with environmental triggers. Increasingly, AMD is recognized as a complex innate immune-mediated disease where complement activation on drusen recruits and activates tissue macrophages, perpetuating chronic inflammation and accelerating RPE degeneration.

• Geographic atrophy development: In some patients with dry AMD, progressive RPE loss occurs in a relatively well-demarcated pattern, termed geographic atrophy (GA). This represents focal, severe loss of the RPE-photoreceptor complex with exposure of underlying choroid. The mechanism involves RPE cell death through multiple pathways: complement-mediated direct lysis (from membrane attack complex deposition), oxidative stress-induced apoptosis, and senescence. RPE cells surrounding the atrophic area undergo senescence, characterized by cell cycle arrest and pro-inflammatory secretory phenotype, which fuels continued expansion of the atrophic region. Loss of the RPE's tight junction barrier allows inflammatory cells and mediators to access the photoreceptor layer, accelerating photoreceptor death.

• Advanced age: Age is the single most powerful risk factor; prevalence increases exponentially after age 60, with dramatic acceleration beyond 75 years. Aging itself drives accumulation of cellular damage, mitochondrial dysfunction, shortened telomeres, impaired autophagy, and increased oxidative stress—all central to AMD pathogenesis. This is not merely coincidental but reflects fundamental loss of cellular homeostasis with advancing years.

• Genetic predisposition: As discussed above, polymorphisms in complement genes (CFH, C3, CFB) and ARMS2/HTRA1 confer substantial risk. Carriers of high-risk CFH variants have an approximate threefold increased risk. A positive family history of AMD increases an individual's risk by 2-3 fold, even accounting for shared environmental factors. Genetic risk factors appear particularly important in determining not only AMD development but also its progression rate and severity.

• Smoking: Active smoking is among the most modifiable risk factors for AMD, approximately doubling AMD risk through multiple mechanisms: increased oxidative stress, impaired RPE function, reduced antioxidant levels (particularly carotenoids), and enhanced inflammation. Even former smokers retain elevated risk for years after cessation, though continued smoking shows a dose-response relationship with risk. Smoking is thought to accelerate drusen formation and increase progression to neovascular disease.

• Hypertension and cardiovascular disease: Elevated blood pressure correlates with AMD progression, likely through endothelial dysfunction, increased vascular permeability, and enhanced oxidative stress within the choroid. Some studies suggest that antihypertensive medications, particularly calcium channel blockers, may confer modest protection. Atherosclerosis and dyslipidemia similarly increase risk by promoting systemic inflammation and oxidative stress affecting the choroidal vasculature.

• Obesity and metabolic syndrome: Higher BMI correlates with increased AMD incidence and progression, particularly in those with metabolic syndrome. The mechanism likely involves chronic systemic inflammation (elevated C-reactive protein, TNF-α, IL-6), oxidative stress, and impaired glucose metabolism. Obesity-associated adipose tissue inflammation promotes macrophage recruitment to the retina.

• Nutritional factors: Low dietary intake of carotenoids (especially lutein and zeaxanthin—the pigments of the macula) and omega-3 polyunsaturated fatty acids increases AMD risk. The Age-Related Eye Disease Study (AREDS) demonstrated that antioxidants (vitamins C and E, beta-carotene) and zinc modestly reduced progression in intermediate-to-advanced dry AMD. This reflects the oxidative vulnerability of the photoreceptor-rich macula and the importance of dietary antioxidants.

• Light exposure and UV radiation: Chronic exposure to blue light and UV radiation over decades may accelerate photoreceptor and RPE damage through photo-oxidative mechanisms. However, the contribution of light exposure to overall AMD risk, separate from age, remains uncertain. Some evidence suggests that cumulative lifetime UV exposure increases risk.

• Systemic inflammation and C-reactive protein: Elevated inflammatory markers, particularly high-sensitivity C-reactive protein (hsCRP), correlate with AMD presence and progression, consistent with the inflammatory model of AMD pathogenesis. Chronic systemic infections and periodontal disease have also been epidemiologically associated with AMD risk, though causality remains unproven.

• Blurred or distorted central vision (metamorphopsia): Patients with exudative AMD and some with advanced dry AMD report wavy or distorted appearance of straight lines (e.g., door frames, grid patterns)—a phenomenon termed metamorphopsia. This results from subretinal fluid accumulation or scarring that mechanically distorts the photoreceptor layer alignment. Metamorphopsia is particularly significant as it may be the earliest symptom of wet AMD and warrants urgent ophthalmology evaluation. The distortion is central and progressive, unlike the peripheral field defects of glaucoma.

• Difficulty reading and recognizing faces: Patients report progressive difficulty with reading, writing, and facial recognition due to loss of central visual acuity. Unlike cortical visual impairment, patients typically retain good ability to navigate spaces using peripheral vision. This dissociation—preserved navigation but impaired reading—is characteristic of macular disease and helps distinguish AMD from other causes of vision loss.

• Dark spot or scotoma in central vision (central scotoma): In intermediate-to-advanced disease, patients may notice a dark spot or missing area in the center of their visual field corresponding to the location of drusen or atrophy. This scotoma expands as disease progresses. The scotoma's size and location determine functional impact; a scotoma in the fovea causes the most severe acuity loss.

• Photopsia (flashing lights): Patients with exudative AMD, particularly those with retinal tears or hemorrhage, may report sudden onset of flashing lights (photopsia) or shower of floaters, signaling acute retinal pathology requiring emergent evaluation.

• Decreased contrast sensitivity: Even with preserved acuity on standard charts, patients report difficulty seeing in dim lighting and reduced ability to distinguish objects from background—reflecting early RPE dysfunction before major structural changes occur.

• Physical exam findings—drusen: On dilated funduscopic examination, the hallmark of dry AMD is the presence of drusen, which appear as small yellowish spots beneath the retina in the macula. Drusen are classified by size: hard drusen (<63 micrometers, usually associated with normal vision), intermediate drusen (63-125 micrometers, associated with increased risk of progression), and soft drusen (>125 micrometers, associated with higher AMD risk). Confluent or numerous soft drusen constitute the primary anatomic feature of intermediate AMD. The irregular, hypodense appearance of soft drusen on fundoscopy contrasts with the better-defined hard drusen.

• Physical exam findings—retinal pigmentation changes: Along with drusen, areas of irregular pigmentation appear, including hyperpigmentation (clumping of RPE) and hypopigmentation (patchy RPE loss/depigmentation). These changes reflect heterogeneous RPE dysfunction and early atrophy. RPE changes often precede visible structural damage and indicate progression of disease.

• Physical exam findings—geographic atrophy: In advanced dry AMD, well-demarcated areas of RPE and photoreceptor loss appear as sharply bordered regions of choroidal hypopigmentation, exposing the underlying white sclera and choroidal vessels. The atrophic patches may be small and focal or large and confluent, and their location determines functional impact (foveal involvement causes severe acuity loss; extrafoveal atrophy may spare reading vision).

• Physical exam findings—exudative changes: In wet AMD, dilated examination reveals subretinal hemorrhage (dark red areas), subretinal fluid (dull, grayish appearance), retinal elevation indicating CNV, hard exudates (yellow lipid deposits), and sometimes a gray or greenish neovascular membrane. Retinal pigment epithelium detachment (PED) may also be visible—a smooth elevation of the RPE from Bruch's membrane, which can be avascular (drusenoid PED) or vascularized (indicating CNV).

• Important clinical variant—polypoidal choroidal vasculopathy (PCV): This is a variant of exudative AMD, more common in Asian populations, characterized by branching choroidal vessels with terminal nodular aneurysms that leak fluid. Clinically, patients may present with recurrent hemorrhage despite treatment, and imaging reveals a distinctive branching vascular pattern. PCV has somewhat different treatment response characteristics compared to typical CNV.

• Dilated retinal examination (dilated fundus exam): The foundational diagnostic step; dilated examination with indirect or direct ophthalmoscopy allows visualization of drusen, RPE changes, atrophy, and exudative features. However, formal diagnosis increasingly relies on imaging rather than clinical examination alone, as subtle findings may be missed clinically. The pupil dilation should ideally last 4-6 hours, requiring patient caution with driving. A systematic approach examining the macula for drusen characteristics, pigmentation changes, and choroidal visibility is essential.

• Optical coherence tomography (OCT): This is the gold standard imaging modality for AMD diagnosis and monitoring, providing cross-sectional images of retinal structure at near-histologic resolution. On OCT, drusen appear as subretinal nodules with variable reflectivity; soft drusen show poorly defined boundaries and heterogeneous internal reflectivity, while hard drusen have well-defined borders. Geographic atrophy appears as a well-defined region of RPE loss with underlying choroidal hyporeflectivity and photoreceptor layer disruption. In exudative AMD, OCT reveals intraretinal or subretinal fluid as hyporeflective (dark) spaces and allows measurement of fluid volume and photoreceptor layer thickness—critical for monitoring treatment response. The presence and status of the photoreceptor inner segment/outer segment (IS/OS) junction predicts visual prognosis; preservation of this junction indicates better potential for functional recovery with treatment. OCT angiography (OCTA), a non-contrast enhancement of OCT, visualizes neovascular flow without dye, allowing detection of choroidal neovascularization as a tangle of vessels with flow signal at the level of or beneath the RPE.

• Fundus autofluorescence (FAF): This imaging modality detects lipofuscin accumulation in RPE cells, appearing as areas of hyperautofluorescence (bright areas indicating lipofuscin accumulation and RPE damage). Areas of hypoautofluorescence (dark regions) indicate RPE loss or atrophy. FAF is particularly valuable for detecting and monitoring geographic atrophy, as it clearly delineates atrophic boundaries and can predict progression at the edges of atrophy. Speckled hyperautofluorescence in regions of drusen correlates with RPE metabolic dysfunction.

• Fluorescein angiography (FA): Though largely supplemented by OCT and OCTA, FA remains useful in specific scenarios. FA classification of CNV as "classic" (well-demarcated hyperfluorescent area on early frames, corresponding to angiographically visible neovascular membrane) versus "occult" (stippled hyperfluorescence without classic appearance) has prognostic significance; classic CNV is more amenable to anti-VEGF treatment. FA also identifies retinal hemorrhage and areas of RPE window defects (appearing as hyperfluorescent areas from underlying choroidal fluorescence).

• AMD disease staging and severity classification: The simplified AMD classification system (used clinically and in research) stratifies patients as follows: (1) Normal or minimal changes (no drusen or minimal hard drusen); (2) Early AMD (multiple hard drusen or nonconfluent soft drusen); (3) Intermediate AMD (one or more drusen ≥125 μm or RPE abnormalities); (4) Advanced AMD, subdivided into (a) geographic atrophy (focal RPE loss in dry AMD) or (b) exudative AMD with CNV. This classification scheme predicts progression risk; patients with intermediate AMD have approximately 25% risk of progressing to advanced disease within

Immediate step in suspected wet AMD

• Urgent ophthalmology referral (days, not weeks): new metamorphopsia or acute central vision loss implies active choroidal neovascularization; photoreceptors lost to subretinal fluid and hemorrhage do not recover, so time-to-injection drives final acuity.

Dry (non-exudative) AMD

• AREDS2 oral supplement: antioxidants plus zinc — vitamin C 500 mg, vitamin E 400 IU, lutein 10 mg, zeaxanthin 2 mg, zinc oxide 80 mg, cupric oxide 2 mg daily. Reduces progression to advanced AMD in intermediate AMD (extensive intermediate/large drusen) or advanced AMD in one eye. Copper is included to prevent zinc-induced copper deficiency (myelopathy, sideroblastic-appearing anemia).
• Beta-carotene is contraindicated in current and former smokers (increased lung cancer incidence in prior chemoprevention trials); lutein/zeaxanthin replaced it in AREDS2 for this reason.
• Complement inhibitors for geographic atrophy: intravitreal pegcetacoplan (C3 inhibitor) and avacincaptad pegol (C5 inhibitor) slow lesion enlargement but have not been shown to improve visual acuity; both increase the risk of conversion to neovascular AMD (requiring ongoing OCT surveillance), and intraocular inflammation — including rare occlusive retinal vasculitis with pegcetacoplan — has been reported.
• Risk-factor modification: smoking cessation, blood pressure and lipid control, dark leafy greens/omega-3-rich diet, home Amsler grid self-monitoring.

Wet (exudative) AMD

• Intravitreal anti-VEGF agents — first line (AAO PPP): aflibercept, ranibizumab, faricimab (bispecific VEGF-A/angiopoietin-2), or off-label bevacizumab, given monthly initially then by treat-and-extend or PRN dosing guided by OCT fluid.
• Escalation: switch agents for persistent fluid; extend intervals with longer-acting or higher-dose agents. Implantable refillable delivery devices exist but are a niche, specialty-center option, not routine escalation.
• Second line/adjunct: verteporfin photodynamic therapy, particularly for polypoidal choroidal vasculopathy; thermal laser photocoagulation is now rarely used (extrafoveal lesions only) because it destroys overlying retina.
• Contraindicated: intravitreal injection into an eye with active ocular or periocular infection.

Complications of the disease

• Disciform scar: organized subretinal fibrosis replacing the neovascular complex after chronic leakage and hemorrhage; funduscopy shows a dense white/yellow subfoveal plaque with permanent dense central scotoma. Signals the end stage of untreated wet AMD.
• Submacular or breakthrough vitreous hemorrhage: rupture of fragile, pericyte-poor neovessels. Sudden painless profound vision loss with loss of the red reflex — an emergency referral, as pneumatic displacement or vitrectomy may be considered.
• Retinal pigment epithelium tear: a vascularized pigment epithelial detachment under hydrostatic and contractile stress rips, most often shortly after starting anti-VEGF; OCT shows a free, scrolled RPE edge with adjacent bare Bruch's membrane and abrupt acuity drop.
• Conversion of dry to wet AMD: hypoxia-driven VEGF upregulation; heralded by new metamorphopsia on the Amsler grid — urgent, not routine, follow-up.
• Expanding geographic atrophy with foveal involvement: progressive absolute central scotoma; legal blindness with preserved ambulation.
• Charles Bonnet syndrome: formed visual hallucinations from cortical release phenomena in a patient with intact insight and normal cognition — reassurance, not antipsychotics.
• Functional sequelae: loss of reading and driving, depression, falls and hip fracture.

Complications of treatment

• Infectious endophthalmitis: the feared injection complication — pain, hypopyon, worsening vision, and vitritis within days. A true ophthalmologic emergency requiring same-day vitreous tap and intravitreal antibiotics.
• Sterile intraocular inflammation / retinal vasculitis and occlusion: an immune-mediated reaction reported particularly with brolucizumab and also with the complement inhibitor pegcetacoplan; painless floaters and vision loss must still be treated as endophthalmitis until excluded.
• Exudative conversion on complement inhibitors: pegcetacoplan and avacincaptad pegol increase the rate of new neovascular AMD in treated eyes, mandating scheduled OCT monitoring.
• Transient IOP elevation, subconjunctival hemorrhage, traumatic cataract, rhegmatogenous retinal detachment: mechanical consequences of the needle and injected volume.
• Theoretical systemic thromboembolic risk from escaped VEGF blockade; clinically small but relevant in recent stroke or MI.
• Verteporfin photodynamic therapy: cutaneous photosensitivity for 5 days after infusion (strict avoidance of direct sunlight and bright indoor light; protective clothing and dark glasses) per the verteporfin label, plus transient acute vision decline.
• Zinc-only supplementation: copper deficiency.

• **Painless, gradual, bilateral loss of central vision with preserved peripheral navigation in a patient over 50 = AMD.** Contrast with open-angle glaucoma (peripheral field loss first) and cataract (diffuse blur, glare, dimmed red reflex).
• Drusen are the buzzword for dry AMD; metamorphopsia — straight lines appearing wavy on the Amsler grid — is the buzzword for conversion to wet AMD and the single most testable red-flag symptom.
• Single best next step for new metamorphopsia: urgent ophthalmology referral for dilated exam and OCT, not reassurance, not repeat acuity in 6 months. OCT showing intraretinal/subretinal fluid confirms neovascular AMD; fluorescein angiography is the classic older answer choice.
• Wet AMD is treated with intravitreal anti-VEGF (aflibercept, ranibizumab, faricimab, off-label bevacizumab) per the AAO Preferred Practice Pattern. Thermal laser photocoagulation is essentially historical; verteporfin photodynamic therapy is largely historical for typical choroidal neovascularization but retains a real adjunctive role in polypoidal choroidal vasculopathy.
• AREDS2 supplements are for intermediate AMD or advanced AMD in one eye only — they do not prevent AMD in patients with no or only small hard drusen, and they do not treat wet AMD. The classic trap: giving beta-carotene to a smoker (lung cancer risk); lutein/zeaxanthin replaced it.
• Complement inhibitors (pegcetacoplan, avacincaptad pegol) slow geographic atrophy growth but do not restore acuity and raise the risk of conversion to neovascular AMD — a nuance increasingly appearing in newer question banks.
• Smoking is the leading modifiable risk factor — cessation counseling is a correct answer in essentially every AMD stem. The genetic association examiners favor is complement factor H (CFH Y402H) and alternative-pathway dysregulation.
• Post-injection eye pain, hypopyon, and worsening vision = endophthalmitis, a same-day emergency for vitreous tap and intravitreal antibiotics — never attribute it to expected post-injection irritation.
• **Formed visual hallucinations with full insight in a visually impaired elder is *Charles Bonnet syndrome***, not psychosis, delirium, or Lewy body dementia; management is reassurance and vision rehabilitation.