Changes seen on dilated fundus exam
To view the macula, ask the patient to look directly at the light during direct fundoscopy.
Dry ARMD displays drusen and changes in the retinal pigment epithelium. Drusen are discrete, round yellow lesions. Changes in the retinal pigment epithelium may be subtle tiny darkly colored patches in the macula near areas of lighter patches (see How ARMD develops).
Wet ARMD may appear as a dark red or green discoloration in the macula and requires immediate referral.
End-stage ARMD may demonstrate a well-delineated geographic pattern corresponding to retinal atrophy or scarring. Large blood vessels are usually visible in the base of these areas. Any macular lesions found in a patient without a diagnosis of ARMD or other maculopathy must have an ophthalmology referral (TABLE 1).
TABLE 1
Referral guide for age-related macular degeneration
| GROUP 1 | IMMEDIATE REFERRAL (THAT DAY) |
| New onset of decreased vision of unknown cause | |
| New onset of metamorphopsia (crooked telephone poles or new findings on the Amsler grid test) | |
| New onset of a scotoma (losing words while reading) | |
| Retinal hemorrhages | |
| GROUP 2 | PROMPT REFERRAL (WITHIN 1 MONTH) |
| Drusen or retinal pigment epithelium changes seen without a previous diagnosis of ARMD | |
| History of long-standing metamorphopsia or scotoma without a previous diagnosis of ARMD | |
| GROUP 3 | ROUTINE REFERRAL (WITHIN 6 MONTHS) |
| Diagnosis of ARMD, but has not seen an ophthalmologist in more than 1 year | |
| Age over 60, but has not seen an ophthalmologist in more than 2 years | |
How ARMD develops
Dry ARMD demonstrating yellow-white drusen with areas of patchy hyperpigmentation of the retinal pigment epithelium. This patient has 20/30 vision and metamorphopsia on Amsler grid testing.
The greenish hue indicates bleeding under the retina. The yellow-white lesions represent sub-retinal scarring. This patient has 20/400 vision and a large scotoma on Amsler grid testing.
Pathologically, ARMD damages the macula in 1 of 2 ways, giving rise to the 2 forms of ARMD, wet and dry. Dry ARMD accounts for 80% of all cases of ARMD.12 In this form, the retinal pigment epithelium (RPE) degenerates as a result of the intracellular deposition of yellow metabolic waste products known as drusen. Drusen are typically accompanied by subtle, progressive changes in the pigmentation of the RPE (FIGURE 2). Without the nutritional support of the RPE, the overlying retina cells slowly atrophy causing a loss of central visual acuity. Wet ARMD is less common, but accounts for 80% of the severe vision loss from ARMD.12 In this form, neovascularization from the arterial system underlying the RPE breaks through the RPE barrier and quickly spreads underneath the retina, causing bleeding and fibrosis which can rapidly destroy the macula (FIGURE 3).
FIGURE 2
Dry ARMD
Dry ARMD demonstrating yellow-white drusen with areas of patchy hyperpigmentation of the retinal pigment epithelium. This patient has 20/30 vision and metamorphopsia on Amsler grid testing.
FIGURE 3
Wet ARMD
The greenish hue indicates bleeding under the retina. The yellow-white lesions represent sub-retinal scarring. This patient has 20/400 vision and a large scotoma on Amsler grid testing.
Treatment for dry macular degeneration
Vitamins confer modest benefit
Some patients with dry ARMD may benefit modestly from certain over-the-counter vitamin supplements. The Age-Related Eye Disease Study found that patients with extensive drusen but no advanced macular degeneration in either eye had an 11% chance of going from legal driving vision to legal blindness within 5 years. However, those who took the once-a-day formulation13 shown in TABLE 2 exhibited a modest drop in risk to 10% over 5 years. More encouraging, patients with advanced macular degeneration in the control eye reduced their chances of legal blindness from 28% to 17% with the supplement (strength of recommendation [SOR]: A14; level of evidence [LOE]: 1, randomized controlled trial [RCT]).
Ten mg of Lutein alone or combined with antioxidants has shown some promise in short-term studies15 (SOR: B; LOE: 2, RCT), but further research will be required.
TABLE 2
Recommended daily vitamin doses for dry ARMD patients
| VITAMIN | DOSE |
|---|---|
| Zinc | 80 mg |
| Vitamin C | 500 mg |
| Vitamin E | 400 IU |
| Beta-carotene | 15 mg |
| Copper | 2 mg |
| The recommended once a day dose from the Age-Related Eye Disease Study. Copper was included in the formulation to prevent a zinc-induced copper deficient anemia.13 It should also be noted that smokers may be at an increased risk of lung cancer from excessive beta-carotene use13 and special formulations for smokers are available. | |
Treatment for wet macular degeneration
Laser treatment most common choice
Though many types of therapy are available, patients with wet ARMD will usually undergo photodynamic therapy or conventional laser therapy.
Photodynamic therapy uses a photosensitizing agent with an affinity for neovascular tissue. After injection into the bloodstream, the agent is light-activated to induce thrombosis of the neovascular vessels.16 The Treatment of Age-Related Macular Degeneration with Photodynamic Therapy study showed that treated patients had a greater chance of retaining their vision compared with untreated patients, and that about 1 in 6 treated patients experienced some improvement in vision (SOR: A; LOE: 1, RCT).17 Unfortunately, recurrence of neovascular tissue is common and retreatment is often necessary.