What is the difference between dry and wet AMD?

Dry AMD (non-exudative) is the more common form (85-90%), characterized by drusen deposits and RPE changes that progress slowly. Wet AMD (exudative/neovascular) is less common but far more visually threatening -- abnormal blood vessels (CNV) grow under the retina and leak fluid, causing rapid distortion and vision loss. Dry AMD can convert to wet AMD.

What does the Amsler grid test for?

The Amsler grid is a simple grid of horizontal and vertical lines with a central fixation dot. Patients fixate on the center and note any distortion, wavy lines, or missing areas. It detects metamorphopsia and scotomas, which may indicate wet AMD or macular pathology. It is used at home for self-monitoring and at office visits for baseline comparison.

What are anti-VEGF injections and why are they given?

Anti-VEGF (anti-vascular endothelial growth factor) injections are intravitreal treatments for wet AMD. VEGF drives the growth of abnormal choroidal neovascularization (CNV) that leaks fluid and damages the retina. Anti-VEGF agents (ranibizumab, aflibercept, bevacizumab, faricimab) block VEGF, causing regression of CNV and reducing fluid. Injections are given monthly or on a treat-and-extend schedule.

What is the AREDS2 formula?

AREDS2 is a specific nutritional supplement formula studied in the Age-Related Eye Disease Study 2 clinical trial. It contains: vitamin C (500 mg), vitamin E (400 IU), zinc (80 mg), copper (2 mg), lutein (10 mg), and zeaxanthin (2 mg). It reduces the risk of progression to advanced AMD in patients with intermediate AMD or advanced AMD in one eye. It is not beneficial for those with no or only small drusen.

Why is sudden vision change in an AMD patient urgent?

Patients with dry AMD can convert to wet AMD, with new choroidal neovascularization causing rapid accumulation of sub- or intraretinal fluid. This can cause rapid central vision loss within days to weeks if untreated. Wet AMD responds well to anti-VEGF injections, but treatment delay significantly worsens outcomes. Any sudden new metamorphopsia or vision change in an AMD patient requires same-day or next-day evaluation.

Age-Related Macular Degeneration (AMD)

What Is Age-Related Macular Degeneration?

Age-related macular degeneration (AMD) is a degenerative disease affecting the macula -- the central area of the retina responsible for sharp, detailed vision. It is the leading cause of severe, irreversible central vision loss in people over age 50 in developed countries. AMD does not affect peripheral vision, so patients retain mobility and independence but often cannot read, drive, or recognize faces.

Dry AMD (Non-Exudative)

Dry AMD accounts for approximately 85-90% of all AMD cases. It is characterized by:

Drusen -- yellowish deposits of debris beneath the retinal pigment epithelium (RPE). Small hard drusen are normal aging; large soft drusen are a risk factor for progression.
RPE changes -- pigment irregularities, hyper- and hypopigmentation
Geographic atrophy (GA) -- advanced dry AMD where large areas of RPE and photoreceptors are lost, causing a scotoma (blind spot)

Dry AMD progresses slowly over years. There is no treatment that reverses dry AMD, but nutritional supplementation (AREDS2 formula) can slow progression in intermediate-to-advanced AMD.

💡 Clinical Tip: The AREDS2 formula (lutein/zeaxanthin, vitamin C, vitamin E, zinc, copper) has been shown in clinical trials to reduce the risk of advanced AMD in patients with intermediate AMD or advanced AMD in one eye. The CPOA may educate patients about supplementation and monitor for conversion to wet AMD.

Wet AMD (Exudative / Neovascular)

Wet AMD accounts for only 10-15% of AMD cases but causes about 90% of severe vision loss from AMD. It involves:

Growth of abnormal new blood vessels from the choroid beneath the RPE and retina (choroidal neovascularization, CNV)
These vessels are fragile and leak fluid and blood into the retinal layers (subretinal or intraretinal fluid)
Symptoms: rapid distortion or blurring of central vision, metamorphopsia (straight lines appear wavy), central scotoma

Wet AMD can progress rapidly (days to weeks) and requires urgent treatment.

Risk Factors

Advanced age (greatest risk factor)
Smoking (doubles the risk)
Family history / genetic variants (CFH and ARMS2 genes)
Caucasian race
Cardiovascular disease, obesity, hypertension
UV exposure

Diagnosis and Monitoring

The CPOA plays a key role in AMD monitoring through:

Amsler grid testing: Patient fixates on the central dot and reports any distortion, blurring, or missing areas in the grid. The standard Amsler grid detects metamorphopsia and scotomas. Changes from the patient's baseline may indicate wet AMD conversion.
OCT imaging: The primary tool for detecting and monitoring wet AMD. OCT shows drusen, fluid under or within the retina (subretinal fluid, intraretinal fluid), CNV, and retinal thickness.
Fundus photography: Documents drusen distribution and geographic atrophy extent.
Fluorescein angiography (FA) or OCT-A: Identifies CNV and guides treatment decisions.

⚠️ Common Mistake: If a patient with dry AMD reports sudden new distortion or vision change, do not schedule a routine follow-up -- alert the physician immediately. Conversion to wet AMD requires urgent treatment within days to preserve vision.

Treatment

Dry AMD

AREDS2 nutritional supplements for intermediate/advanced AMD
Lifestyle modification (smoking cessation, diet, exercise)
Low vision rehabilitation for geographic atrophy

Wet AMD

Anti-VEGF intravitreal injections are the standard of care. VEGF (vascular endothelial growth factor) drives CNV formation. Anti-VEGF agents suppress this:

Ranibizumab (Lucentis)
Bevacizumab (Avastin, off-label)
Aflibercept (Eylea)
Faricimab (Vabysmo)

Injections are given monthly initially, then spaced based on treatment response (treat-and-extend or PRN protocols). The CPOA prepares the patient, instills anesthetic drops, and ensures sterile preparation.

Key Takeaways

AMD is the leading cause of central vision loss in adults over 50; peripheral vision is preserved
Dry AMD (90%): drusen and RPE changes; geographic atrophy in advanced disease; AREDS2 slows progression
Wet AMD (10%): CNV causes rapid vision loss from fluid/blood; requires urgent anti-VEGF injection
Amsler grid at home monitors for metamorphopsia; changes require urgent physician notification
OCT is the primary imaging tool for monitoring AMD
Smoking cessation is the most important modifiable risk factor

Age-Related Macular Degeneration (AMD) | CPOA Exam