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Age-related macular degeneration (AMD) is the leading cause of irreversible central vision loss in adults over 50 in developed countries, affecting approximately 11 million Americans. For the COA, AMD is an important clinical topic because it appears across multiple exam domains -- Assessments (Amsler grid, visual acuity), Imaging (fundus photography, OCT), and Assisting with Procedures (anti-VEGF injection preparation, patient education).
AMD affects the macula -- the central 5-6mm of the retina responsible for high-acuity central vision and color perception. The disease is driven by accumulation of drusen (metabolic waste deposits between the RPE and Bruch's membrane), RPE dysfunction, and in its advanced forms, either geographic atrophy of the RPE (dry AMD) or choroidal neovascularization with subretinal exudation (wet AMD).
This guide covers the clinical classification of AMD stages, the distinct features of dry and wet AMD, Amsler grid testing technique, fundus and OCT findings, the AREDS2 supplement recommendation, anti-VEGF injection preparation, and patient education for home monitoring.
| Feature | Dry AMD | Wet AMD |
|---|---|---|
| Prevalence | 85-90% of AMD cases | 10-15% of AMD cases |
| Key pathology | Drusen, RPE atrophy, geographic atrophy (GA) | Choroidal neovascularization (CNV), leakage, bleeding |
| Vision loss | Slow, progressive central blur | Rapid (days to weeks) if untreated |
| Amsler grid | May be normal until advanced; possible mild distortion | Metamorphopsia (wavy lines), central scotoma |
| OCT findings | Drusen (sub-RPE deposits), RPE irregularity, GA (outer retinal atrophy) | Subretinal fluid, intraretinal fluid, PED, subretinal blood |
| Fundus appearance | Yellow-white drusen deposits, pigmentary changes | Grayish-green CNV membrane, blood, hard exudates, fluid |
| Treatment | AREDS2 supplements (intermediate/advanced); monitoring | Anti-VEGF intravitreal injections (Eylea, Lucentis, etc.) |
The AREDS2 study established the most widely used clinical staging system for AMD. The stage determines risk of progression and guides treatment decisions, including whether to recommend supplements. The COA should understand the stages well enough to document findings accurately.
No drusen or only a few small drusen (<63 microns). No pigmentary changes. Normal-appearing macula. No supplementation indicated.
Multiple small drusen (<63 microns), a few medium drusen (63-124 microns), or RPE pigmentary abnormalities. Vision is usually normal. Risk of progression to advanced AMD over 5 years: ~1.3%.
AREDS2 supplements NOT recommended at this stage (insufficient evidence of benefit).
At least one large drusen (≥125 microns) in either eye, OR extensive medium drusen, OR geographic atrophy not involving the foveal center. Mild to moderate visual symptoms. Risk of progression: ~18% over 5 years.
AREDS2 supplements RECOMMENDED.
Geographic atrophy involving the foveal center, OR wet AMD (neovascular AMD with CNV) in one or both eyes. Significant central vision loss. Risk of fellow eye progression: ~47% over 5 years in those with advanced AMD in one eye only.
AREDS2 supplements recommended for the fellow eye. Active wet AMD treated with anti-VEGF injections.
Small Drusen
<63 microns (smaller than a vein at disc margin)
Often called "hard drusen" -- discrete, well-defined borders
Medium Drusen
63-124 microns
Yellow-white subretinal deposits; can be hard or soft
Large Drusen
≥125 microns (larger than a large vein at disc margin)
"Soft drusen" -- soft, indistinct borders; higher risk marker
The Amsler grid is the most commonly used chair-side screening test for macular function. It tests the central 20 degrees of visual field (10 degrees on each side of fixation) and is particularly sensitive to metamorphopsia (distortion) -- the symptom most commonly reported in early wet AMD. The COA performs and documents Amsler grid testing at AMD monitoring visits.
New Amsler Grid Changes: Urgent Notification
A patient with known AMD who reports new metamorphopsia or a new scotoma on the Amsler grid should be seen urgently -- same day or next day. This finding may represent conversion from dry to wet AMD, and anti-VEGF treatment started within days to weeks of symptom onset gives the best visual outcomes. The COA who takes this call at the front desk should escalate to the physician or senior staff immediately.
Opterio's COA practice questions cover AMD staging, Amsler grid findings, OCT interpretation, and anti-VEGF preparation with detailed explanations.
OCT (optical coherence tomography) has become the primary imaging modality for AMD monitoring and treatment decisions. The COA performs OCT scans and should have a basic ability to recognize key findings in the OCT printout, even though interpretation is the physician's responsibility.
Drusen on OCT
Appear as dome-shaped elevations of the RPE band (hyporeflective or variably reflective beneath the RPE). Hard drusen have well-defined margins; soft drusen have indistinct margins and may coalesce. Drusen under the fovea are the highest-risk location for progression.
Subretinal Fluid (SRF) -- Wet AMD
Hyporeflective (dark) space between the photoreceptor layer and the RPE. Indicates active CNV leakage. The height, extent, and change from previous visit are documented. Resolution of SRF after anti-VEGF injection is a treatment success marker. Some degree of SRF may be tolerated ("treat-and-extend" protocols) if vision is stable.
Intraretinal Fluid (IRF) -- Wet AMD
Dark cystic spaces (intraretinal cysts) within the retinal layers -- most commonly in the outer plexiform and outer nuclear layers. IRF is generally a worse prognostic indicator than SRF and is typically treated more aggressively. The presence of IRF at anti-VEGF follow-up visits usually triggers retreatment.
Geographic Atrophy (GA) -- Advanced Dry AMD
On OCT, GA appears as complete absence of the outer retinal layers (photoreceptors, RPE) with increased signal penetration into the choroid ("hypertransmission"). On fundus photography, GA appears as sharply demarcated areas of RPE loss with visible underlying choroidal vessels. GA is measured in area (mm²) at each visit. Pegcetacoplan (Syfovre) and avacincaptad pegol (Izervay) are FDA-approved treatments for GA (2023-2024).
Camera technique, image documentation, and identifying retinal pathology in photos.
DR staging, imaging findings, and patient education for the COA exam.
Retinal layers, macular anatomy, and foveal structure relevant to COA clinical knowledge.
Full domain breakdown, study timeline, and practice strategies for the COA exam.
Dry AMD (non-neovascular) is the more common form, accounting for approximately 85-90% of AMD cases. It progresses through drusen accumulation, retinal pigment epithelium (RPE) changes, and eventually geographic atrophy (GA) -- areas of complete RPE and photoreceptor loss. Vision loss in dry AMD is gradual and central. Wet AMD (neovascular) involves the growth of abnormal blood vessels (choroidal neovascularization, CNV) from the choroid through the RPE and Bruch's membrane. These vessels can leak fluid, blood, and lipid, causing rapid central vision loss. Wet AMD is less common (10-15%) but accounts for the majority of severe vision loss from AMD. Any patient with dry AMD can convert to wet AMD at any time.
The Amsler grid is a 10x10cm grid of horizontal and vertical lines with a central fixation dot. Testing procedure: (1) Patient wears their near correction (reading glasses). (2) Test one eye at a time, covering the other eye. (3) Hold the grid at standard reading distance (~14 inches or 33cm). (4) Patient fixates on the central dot. (5) Ask specifically: "Are all the lines straight?" "Are there any wavy, distorted, or missing areas?" (6) If abnormalities are present, ask the patient to mark or describe them. Documentation should note which eye, location of distortion, and nature of change (wavy lines = metamorphopsia, missing area = scotoma). Patients with AMD are given Amsler grids for home monitoring and instructed to call immediately if they notice new distortion or a new scotoma -- this is a red flag for conversion to wet AMD.
In dry AMD, OCT shows drusen (elevations under the RPE layer), RPE irregularities, and in advanced cases, areas of geographic atrophy where the outer retinal layers and RPE are completely absent (the OCT signal transmits through clearly to the choroid, showing "hypertransmission"). In wet AMD, the key OCT findings indicating active CNV and leakage are: subretinal fluid (SRF) -- fluid between the photoreceptor layer and RPE; intraretinal fluid (IRF) -- dark cystic spaces within the retinal layers; and sub-RPE fluid (pigment epithelial detachment or PED) -- elevation and detachment of the RPE layer from Bruch's membrane. These fluid signs are the primary targets for anti-VEGF treatment, and monitoring their resolution drives treatment timing decisions.
The AREDS2 (Age-Related Eye Disease Study 2) formula is recommended for patients with intermediate AMD or advanced AMD in one eye to reduce the risk of progression. The AREDS2 formula contains: Vitamin C 500mg, Vitamin E 400 IU, Zinc 80mg (as zinc oxide), Copper 2mg (as cupric oxide, added to prevent zinc-induced copper deficiency), Lutein 10mg, and Zeaxanthin 2mg. The original AREDS formula included beta-carotene, but AREDS2 replaced it with lutein/zeaxanthin because beta-carotene increases lung cancer risk in current or former smokers. The supplements are not recommended for early AMD (small drusen only) because the evidence does not support benefit at that stage.
Anti-VEGF injections (bevacizumab/Avastin, ranibizumab/Lucentis, aflibercept/Eylea, brolucizumab/Beovu, faricimab/Vabysmo) are intravitreal injections given in the office for wet AMD. The COA prepares for the injection by: (1) Performing pre-injection visual acuity (documented for comparison). (2) Measuring IOP (baseline and post-injection check). (3) Instilling topical anesthetic drops (e.g., proparacaine). (4) Instilling topical povidone-iodine 5% solution to the conjunctival surface (key antisepsis step -- must dwell for at least 1 minute). (5) Placing a sterile drape and speculum. (6) Preparing the injection syringe under sterile technique. After injection, the COA checks for perception of hand motion or light (verifies optic nerve perfusion) and documents post-injection IOP.