Diagnosis: Age-related dry macular degeneration
This patient has age-related macular degeneration (ARMD or AMD). There are 2 forms: dry and exudative or “wet” AMD.
Dry Macular Degeneration
The etiology of macular degeneration has not been well elucidated, but it involves disruption of the retinal pigment epithelium (RPE). The RPE is one of the 10 layers of the retina, and one of its functions is to clear waste material. In macular degeneration, due to RPE changes, waste material builds up, and may appear as drusen, or light yellow deposits, in the macula.
Drusen are shown on the optical coherence tomography (OCT) scan of the retina (above left image) and can be seen in the fundus images of this case (image on left). Over time, as the degeneration progresses, photoreceptor damage may occur, leading to retinal atrophy, and significant visual decline. This retinal atrophy is described as geographic atrophy. Focal areas of macular degeneration can cause focal areas of “distortion” in vision, or metamorphopsia. An Amsler grid, can be used by patients to self-screen for any changes in their central vision and for development of metamorphopsia.
An Amsler grid is show in the image below on the left. With a healthy macula, all lines should appear straight. However, areas of the macula affected by macular degeneration, can cause the lines to appear wavy and cause focal scotomas (example shown in image below on right).
Exudative Macular Degeneration
In the exudative or “wet” form of macular degeneration, abnormal new blood vessels grow in the choroid, the layer underlying retina. This angiogenesis is referred to as choroidal neovascularization, and these blood vessels break through the choroid, into the subretinal space, and can bleed due to their abnormal formation. Bleeding into the subretinal space, in addition to causing sudden vision changes, can lead to scarring in the subretinal space, leading to irreversible vision loss. However, the development of intravitreal anti-VEGF injections, has revolutionized ophthalmologist’s ability to treat wet AMD (see “Treatment” section below). The above left fundus photo shows a subretinal hemorrhage centrally near the fovea from choroidal neovascularization. The yellow flecks along the retinal vessels represent lipid exudates. The left image represents an OCT through this area which shows subretinal and intraretinal fluid due to choroidal neovascularization. (Credit for Above and Left Images: © 2020 American Academy of Ophthalmology)
Studies have shown formulations containing Vitamin C, Vitamin E, Copper, Zinc, zeaxanthin, and lutein, referred to as the AREDS2 vitamins, have slowed the progression of dry macular degeneration. The prior formulation or “AREDS vitamins,” contained B-carotene and did not contain zeaxanthin and lutein. However, these modifications were made following beneficial findings in the AREDS2 study. Additionally, the Beta-carotene in the original AREDS formulation was associated with an increased risk of lung cancer in patients with smoking history. Therefore, a separate B-carotene free formulation, was recommended in these patients, prior to AREDS2.
Wet AMD responds well to intravitreal anti-VEGF injections, though multiple, recurrent injections may be necessary. The anti-VEGF is thought to decrease the neovascularization which occurs in wet AMD.
References and Additional Resources:
- “Eyewiki: Age Related Macular Degeneration.” Available at: https://eyewiki.aao.org/Age-related_macular_degeneration.
- Age-Related Eye Disease Study 2 (AREDS2) Research Group. Lutein + Zeaxanthin, and Omega-3 fatty acids for age-related macular degeneration: The AREDS2 Randomized Clinical Trial. JAMA. 2013;309(19):2005-2015.
- National Eye Institute: Age-Related Eye Disease Studies (AREDS/AREDS2). Available at: https://www.nei.nih.gov/research/clinical-trials/age-related-eye-disease-studies-aredsareds2.
Case 7 Index