What is the difference between dry and wet AMD?

Dry AMD involves the gradual accumulation of drusen deposits under the retina and eventual geographic atrophy, progressing slowly over years. Wet AMD involves choroidal neovascularization, where abnormal blood vessels grow beneath the retina and leak blood or fluid, causing rapid vision loss. Dry AMD is more common (80-90% of cases), while wet AMD is more severe but treatable with anti-VEGF injections.

How does the Amsler grid help detect AMD progression?

The Amsler grid is a home monitoring tool with a grid pattern and central dot. Patients view it daily with each eye individually at reading distance. New areas of line distortion (metamorphopsia) or missing sections (scotomas) suggest macular changes that require immediate evaluation. It is especially important for detecting the onset of wet AMD in patients with existing dry AMD.

What is the AREDS2 supplement formula?

AREDS2 is a specific nutritional supplement combination shown to reduce the risk of AMD progression by about 25% in patients with intermediate or advanced disease. It contains vitamin C (500 mg), vitamin E (400 IU), lutein (10 mg), zeaxanthin (2 mg), zinc (80 mg), and copper (2 mg). It replaced the original AREDS formula by substituting lutein and zeaxanthin for beta-carotene, which was linked to increased lung cancer risk in smokers.

Can dry AMD turn into wet AMD?

Yes, dry AMD can convert to wet AMD at any stage. This is why regular monitoring with OCT and Amsler grid testing is so important. Conversion to wet AMD is considered an urgent situation because anti-VEGF treatment should begin promptly to prevent irreversible vision loss from subretinal fluid and hemorrhage.

AMD (Age-Related Macular Degeneration): COA Exam Guide

What Is Age-Related Macular Degeneration?

Age-Related Macular Degeneration (AMD) is a progressive disease that damages the macula, the small central portion of the retina responsible for sharp, detailed vision. It is the leading cause of irreversible central vision loss in adults over 50. As a COA, you will encounter AMD frequently and need to understand both its forms, risk factors, and the role you play in monitoring and patient education.

The macula contains the highest concentration of cone photoreceptors, making it essential for tasks like reading, driving, and recognizing faces. When AMD damages these cells, patients retain peripheral vision but lose the detailed central vision they rely on most.

Dry AMD vs. Wet AMD

Dry (Atrophic) AMD

Dry AMD accounts for roughly 80-90% of all AMD cases. It develops slowly as small yellowish deposits called drusen accumulate beneath the retinal pigment epithelium (RPE). Think of drusen as tiny pebbles building up under a smooth road surface. Over time, they disrupt the nutrient exchange between the RPE and photoreceptors, causing gradual cell loss.

Drusen are classified by size:

Small drusen (under 63 microns): common with aging, usually not clinically significant
Intermediate drusen (63-124 microns): associated with increased AMD risk
Large drusen (125 microns or more): strongly associated with progression to advanced AMD

In advanced dry AMD, large areas of RPE and photoreceptor loss develop, known as geographic atrophy (GA). This appears as well-defined patches of depigmentation on fundus examination.

Wet (Neovascular or Exudative) AMD

Wet AMD is less common but far more aggressive. It involves the growth of abnormal, fragile blood vessels beneath the retina, a process called choroidal neovascularization (CNV). These vessels leak blood and fluid into the subretinal space, causing rapid and severe vision loss. If dry AMD is like slow erosion of a road, wet AMD is like a sudden sinkhole opening beneath it.

Assuming dry AMD cannot convert to wet AMD. Patients with dry AMD should be monitored regularly because conversion to wet AMD can occur at any time and requires urgent treatment.

Risk Factors

Several factors increase the likelihood of developing AMD:

Age: risk increases significantly after 50, with highest prevalence over 75
Smoking: the most significant modifiable risk factor, doubling or tripling risk
Family history: genetics play a strong role, particularly complement factor H variants
Hypertension: chronic high blood pressure damages retinal vasculature
UV light exposure: cumulative sun exposure contributes to oxidative damage
Diet: low intake of antioxidants and omega-3 fatty acids is associated with higher risk

Diagnostic Tools and Monitoring

Amsler Grid

The Amsler grid is a simple but valuable home monitoring tool. It consists of a grid of horizontal and vertical lines with a central fixation dot. Patients view the grid at reading distance with each eye separately. Any metamorphopsia (wavy or distorted lines) or scotomas (missing areas) suggests macular pathology and warrants prompt evaluation.

When instructing patients on Amsler grid use, remind them to test each eye individually, wear their reading correction, and report any new distortion or missing areas immediately. Post the grid on a refrigerator or bathroom mirror for daily checks.

OCT and Fundus Imaging

Optical coherence tomography (OCT) is the gold standard for detecting subretinal fluid, drusen volume, and geographic atrophy. Fundus photography documents drusen distribution and pigmentary changes over time. Fluorescein angiography (FA) identifies active CNV leakage in wet AMD cases.

Treatment Approaches

Dry AMD Management

There is currently no cure for dry AMD, but the AREDS2 formula (Age-Related Eye Disease Study 2) has been shown to slow progression in patients with intermediate or advanced disease. This supplement includes vitamins C and E, lutein, zeaxanthin, zinc, and copper. Lifestyle modifications like smoking cessation, UV protection, and a diet rich in leafy greens also play important roles.

Wet AMD Treatment

Anti-VEGF injections are the primary treatment for wet AMD. Medications like ranibizumab (Lucentis), aflibercept (Eylea), and bevacizumab (Avastin) block vascular endothelial growth factor, reducing abnormal vessel growth and leakage. Injections are administered intravitreally and typically require ongoing treatment at regular intervals.

Anti-VEGF therapy does not cure wet AMD but can stabilize or improve vision when administered consistently. Missing appointments can lead to irreversible vision loss from continued CNV leakage.

Why This Matters for COAs

As a COA, you play a direct role in AMD care. You perform OCT scans, capture fundus photographs, instruct patients on Amsler grid use, and document visual acuity changes between visits. You are often the first to notice progression signs during pre-testing. Understanding AMD stages helps you prioritize urgent findings and communicate effectively with the physician.

Key Takeaways

AMD is classified as dry (drusen, geographic atrophy) or wet (choroidal neovascularization)
Dry AMD is more common; wet AMD causes more rapid, severe vision loss
Smoking is the strongest modifiable risk factor
The Amsler grid helps patients monitor for new distortion or scotomas at home
Anti-VEGF injections are the standard treatment for wet AMD
AREDS2 supplements can slow progression in intermediate and advanced dry AMD
OCT is the key imaging modality for monitoring fluid and drusen changes