Age-Related Macular Degeneration: COA Guide to Testing and Patient Care

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.

Dry AMD vs. Wet AMD: Core Comparison

AREDS2 Classification: Staging AMD

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.

No AMD (Category 1)

No drusen or only a few small drusen (<63 microns). No pigmentary changes. Normal-appearing macula. No supplementation indicated.

Early AMD (Category 2)

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).

Intermediate AMD (Category 3)

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.

Advanced AMD (Category 4)

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.

Amsler Grid Testing: Technique and Documentation

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.

Testing Procedure

1. Patient wears near correction (reading glasses)
2. Test one eye at a time (cover fellow eye)
3. Hold grid at 33cm (standard reading distance)
4. Patient fixates on the central dot
5. Ask: "Are all lines straight? Any wavy or missing areas?"
6. Ask patient to mark any abnormal areas on the grid
7. Document findings for each eye separately

Abnormal Findings to Document

• Metamorphopsia: Wavy, distorted lines — most common wet AMD symptom
• Scotoma: Missing or blank area in the grid — absolute or relative
• Micropsia/macropsia: Lines appear smaller/larger than normal
• Location: Central vs. paracentral — document which quadrant
• Change from baseline: Any new or worsening finding = urgent physician notification

OCT in AMD: What the COA Needs to Recognize

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. 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 in "treat-and-extend" protocols if vision is stable.

Intraretinal Fluid (IRF) — Wet AMD

Dark cystic spaces 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 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. Pegcetacoplan (Syfovre) and avacincaptad pegol (Izervay) are FDA-approved treatments for GA (2023–2024).

AMD Risk Factors and Patient Education

Major Risk Factors

• Age: Risk doubles every decade over 50. Most AMD occurs in people over 65.
• Smoking: 2–4× increased risk. The single most important modifiable risk factor.
• Family history: First-degree relative with AMD significantly elevates risk. CFH and ARMS2 gene variants are most relevant.
• Race: More prevalent in people of European descent.
• Large soft drusen: Presence in fellow eye substantially increases risk of progression.

Patient Education Points (COA Role)

• Quit smoking — most impactful modifiable factor
• Take AREDS2 supplements daily if recommended (intermediate/advanced AMD)
• Use Amsler grid at home — check each eye separately every day
• Call immediately if new distortion, new blind spot, or sudden vision change
• Wear UV-blocking sunglasses
• Eat leafy greens, fish (omega-3s), and a Mediterranean-style diet

Anti-VEGF Injection: The COA's Preparation Role

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 plays a key role in preparation:

1. Perform pre-injection visual acuity (documented for comparison)
2. Measure IOP (baseline)
3. Instill topical anesthetic drops (e.g., proparacaine 0.5%)
4. Instill topical povidone-iodine 5% to the conjunctival surface — must dwell for at least 1 minute (key antisepsis step)
5. Place sterile drape and lid speculum
6. Prepare injection syringe under sterile technique

After injection, the COA checks perception of hand motion or light (verifies optic nerve perfusion is maintained) and documents post-injection IOP.