Age-related macular degeneration (AMD) is one of the leading causes of irreversible central vision loss in older adults worldwide. It affects the macula — the small central region of the retina responsible for sharp, detailed vision used in reading, recognizing faces, and driving. Because AMD strikes central vision while usually sparing the periphery, patients can navigate a room yet be unable to read a sentence. Understanding the two forms of AMD — dry and wet — is fundamental for every optometry and ophthalmology student, because their urgency, workup, and management differ profoundly.
What AMD Is
AMD is a degenerative condition of the macula that develops with age. The retinal pigment epithelium (RPE) and photoreceptors in the central retina gradually break down. Early disease may be asymptomatic and detectable only on a dilated fundus examination. As disease advances, central vision deteriorates — first subtly (needing more light to read, mild distortion), later severely.
A useful mental model: think of the RPE as the support layer that nourishes and maintains the photoreceptors. In AMD, this support system fails. In the dry form, the failure is slow and atrophic — cells waste away. In the wet form, the failure provokes abnormal new blood vessels that leak and bleed — damaging vision rapidly.
Risk Factors
Several factors increase the likelihood of developing AMD. Key ones to remember:
- Age — the single strongest risk factor; prevalence rises sharply after 50
- Genetics — family history and certain complement-system gene variants
- Smoking — the most important modifiable risk factor
- Cardiovascular factors — hypertension, elevated cholesterol, and obesity have been associated with increased risk
- Diet and lifestyle — diets low in leafy green vegetables and oily fish; chronic sun exposure has been studied as a possible contributor
- Ethnicity — more common in populations of European descent
As a student, the counseling implication is immediate: smoking cessation and a healthy diet are the two modifiable factors you will emphasize again and again.
Dry AMD: Drusen and Geographic Atrophy
Dry (atrophic) AMD accounts for the great majority of AMD cases and progresses slowly over years. Its hallmark features:
Drusen. Yellow-white deposits beneath the retina, visible on fundus examination. Drusen are the earliest clinical sign. Small, hard drusen in small numbers may be a normal age-related finding; large, soft drusen — especially when numerous and clustered in the macula — signal higher risk of progression.
RPE changes. Pigmentary abnormalities — hyperpigmentation or depigmentation — often accompany drusen and mark areas of stressed or failing RPE.
Geographic atrophy. In advanced dry AMD, well-demarcated zones of RPE and photoreceptor loss appear — “geographic” because the atrophic patches have map-like borders. When atrophy involves the fovea (the very center), central acuity drops substantially. Geographic atrophy is currently irreversible; the cells are gone.
Progression in dry AMD is typically measured in years. Vision may remain functional for a long time, with gradual decline. Importantly, dry AMD can convert to wet AMD at any time — which is why monitoring is essential and patients are taught self-testing.
Wet AMD: Choroidal Neovascularization
Wet (neovascular or exudative) AMD is less common but far more destructive. Abnormal new blood vessels — choroidal neovascularization (CNV) — grow from the choroid through Bruch’s membrane into or under the retina. These vessels are fragile and abnormal:
- They leak fluid, causing macular edema
- They bleed, causing subretinal or intraretinal hemorrhage
- The blood and fluid disrupt the retinal architecture, and subsequent scarring destroys photoreceptors
Why is wet AMD urgent? Because untreated, CNV can cause severe, permanent central vision loss within weeks to months. A patient who notices sudden distortion or a new blind spot needs same-day or next-day evaluation — this is a true clinical priority. The phrase to internalize: dry AMD is watched; wet AMD is acted upon immediately.
Symptoms Compared
| Feature | Dry AMD | Wet AMD |
|---|---|---|
| Onset | Gradual, over years | Sudden, over days to weeks |
| First symptom | Need for brighter light, mild blur | Distortion (straight lines look wavy), sudden blind spot |
| Metamorphopsia (wavy lines) | Usually absent or mild | Classic, prominent |
| Scotoma (blind spot) | Develops slowly, often paracentral | Can appear suddenly, central |
| Vision loss rate | Slow decline | Rapid if untreated |
| Pain | None | None |
| Peripheral vision | Preserved | Preserved |
The single most useful screening question for distinguishing them: “Have straight lines — door frames, tiles, text lines — started looking bent or wavy?” New-onset metamorphopsia points toward wet disease until proven otherwise.
Diagnostic Tools (Conceptual)
Dilated fundus examination. The foundation. With dilation and a slit lamp (or indirect ophthalmoscopy), you look for drusen, pigment changes, atrophy, subretinal fluid, hemorrhage, and hard exudates. Hemorrhage or fluid in the macula of an older patient should raise suspicion of wet AMD.
Optical coherence tomography (OCT). The workhorse of modern AMD diagnosis and follow-up. OCT gives a cross-sectional view of the retinal layers. In dry AMD you see drusen as elevations under the RPE and thinning in geographic atrophy; in wet AMD you see fluid — intraretinal cysts, subretinal fluid, and pigment epithelial detachments. OCT is also how treatment response is monitored over time.
Amsler grid. A simple home-monitoring tool — a grid of straight lines with a central fixation dot. The patient covers one eye, fixates the center, and watches for missing, wavy, or distorted squares. Teach every AMD patient to use it regularly: any new distortion is a reason to call promptly, not at the next routine visit.
Fundus photography and fluorescein angiography. Photography documents baseline appearance for comparison. Fluorescein angiography — dye injected intravenously, photographed as it circulates through retinal and choroidal vessels — can confirm and characterize CNV when the diagnosis is uncertain, showing leakage from abnormal vessels.
Management Overview
Management follows the dry/wet divide.
Dry AMD. There is no treatment that reverses geographic atrophy, so care centers on risk reduction and monitoring:
- Smoking cessation — the highest-yield intervention
- Nutrition — a diet rich in leafy greens, colorful vegetables, and oily fish; large clinical trials (the AREDS and AREDS2 studies) showed that a specific high-dose antioxidant and mineral formulation can slow progression in people with intermediate or advanced dry AMD in at least one eye. This is a nutritional risk-reduction strategy for a defined group — not a cure, and not indicated for early disease or the general public
- UV protection — sensible sunglass use outdoors
- Regular monitoring — scheduled fundus exams and OCT, plus home Amsler grid testing, to catch conversion to wet AMD early
- Low vision rehabilitation — when acuity drops despite everything, referral for magnifiers, lighting advice, eccentric viewing training, and daily-living adaptations (see below)
Wet AMD. The standard of care is anti-VEGF therapy — medications injected into the vitreous that block vascular endothelial growth factor, the signal driving abnormal vessel growth. These injections reduce leakage, often improve vision, and typically require a series of treatments followed by ongoing monitoring, with re-treatment guided by OCT findings. Because treatment works best when started early, rapid referral of suspected wet AMD is one of the most sight-saving actions in eye care. Adjunctive options such as photodynamic therapy or laser exist for selected cases and are specialist decisions.
Low Vision Rehabilitation
When central vision is permanently reduced — most often from advanced dry AMD — rehabilitation restores function, not acuity. Key elements:
- Optical aids — hand and stand magnifiers, telescopic systems, high-add reading spectacles
- Lighting — task lighting dramatically improves reading performance in macular disease
- Eccentric viewing training — teaching the patient to use a healthier paracentral retinal area as a “new fovea”
- Contrast and daily-living adaptations — large-print materials, talking devices, kitchen and mobility strategies
- Psychological support — vision loss in AMD carries real risks of depression and social withdrawal; acknowledging this is part of good care
Referral to low vision services should be proactive, not a last resort — patients benefit most when rehabilitation begins while they still have usable residual vision.
Key Takeaways
- AMD affects the macula, causing central vision loss with preserved peripheral vision.
- Dry AMD (drusen, geographic atrophy) is common and slow; wet AMD (choroidal neovascularization) is less common but urgent — leakage and bleeding can destroy central vision quickly.
- New-onset metamorphopsia (wavy lines) or a sudden scotoma in an older adult = suspect wet AMD and refer promptly.
- OCT is the key diagnostic and monitoring tool; the Amsler grid is the patient’s home early-warning system.
- Dry AMD management = risk reduction (stop smoking, healthy diet, AREDS-type nutrition for eligible patients) + vigilant monitoring.
- Wet AMD management = anti-VEGF therapy, where early treatment gives the best outcomes.
- Low vision rehabilitation — magnifiers, lighting, eccentric viewing, daily-living support — is essential care for advanced disease.
This material is for educational purposes only and does not constitute medical advice. Clinical decisions should always involve qualified supervision.