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Wet versus Dry Macular Degenerative Changes

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Title: Wet versus Dry Macular Degenerative Changes

Author: Nina Boal, MSIV, Thomas Jefferson University

Photographer: James Gilman, CRA, FOPS

Location: Medical Student Education Outline > II. Anatomical Approach to Eye Disease > RETINA> 2. Wet versus Dry Macular degenerative changes

 Overview

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in industrialized countries among people 50 years or older [1]. It is a degenerative disease of the macula (central portion of the retina), that results in central vision loss. Clinically, it is divided into dry (atrophic) or wet (exudative or neovascular). The risk of progressing from dry AMD to wet AMD is estimated at 1 to 4.7 percent in one year and 13 to 18 percent at three years [2].

Dry age-related Macular Degeneration

Macular changes in dry AMD are characterized by subretinal drusen deposits, atrophy of the retinal pigment epithelium (RPE), pigment epithelial detachments, and subretinal pigment epithelial clumping. There is an absence of neovascularization [3]. Dry AMD affects 85 to 90 percent of everyone with AMD [4].

Figure 1. Drusen in Dry AMD

Figure 2. Geographic atrophy in Dry AMD

Wet age-related Macular Degeneration

In wet (or neovascular) AMD, abnormal vessels grow into the subretinal space from the choroidal circulation. These vessels can leak and lead to subretinal hemorrhage, seen in figure 3, and subretinal fluid collections, indicating choroidal neovascularization. The goal is to recognize these new vessels before they bleed and cause a hemorrhagic detachment of the retinal pigment epithelium. Wet AMD is less common than dry AMD, affecting only 10 to 15 percent of people with AMD. However, it accounts for more than 80% of patients with severe visual loss or legal blindness [4].

Figure 3A. Subretinal hemorrhage in Wet AMD

Figure 3B. Fluorescein dye retinal angiography of patient with wet AMD, area of leakage corresponds to hemorrhage in figure 3A

 Presentation

The main symptom of AMD is loss of central vision, but initially AMD may be asymptomatic. Patients with dry AMD describe a gradual loss of vision in the center of their visual field. Patients with wet AMD may describe a more acute visual distortion or loss of central vision as fluid or blood accumulates under the retina.

Work-up

Figure 4 Amsler Grid

 

Treatment of Dry AMD

 There is no proven effective treatment for dry AMD, however these patients may eventually develop wet AMD [3]. To prevent this progression, patients can be advised to stop smoking and take a combination of vitamins and minerals that make up the AREDS formula (Age-Related Eye Disease Study). A combination of antioxidant vitamins plus zinc was shown to protect the eye from further damage from AMD in patients who had more extensive dry and wet AMD [5,6].

Treatment of Wet AMD

In addition to the use of antioxidants and zinc, treatment of wet AMD attempts to stop and prevent neovascularization through:

 Summary Table

 

Dry AMD Wet AMD
85 to 90% of patients with AMD 10 to 15% of patients with AMD
Absence of neovascularization Choroidal neovascularization– subretinal hemorrhage and subretinal fluid collections
Drusen, RPE atrophy, pigment epithelial detachments, subretinal pigment epithelial clumping Drusen, RPE atrophy, pigment epithelial detachments, subretinal pigment epithelial clumping
Slow progression Rapid loss of central vision over weeks to months
Mild to Severe central vision loss More severe vision loss or legal blindness
Treatment:

–          Monitor progression to wet AMD with Amsler grid

–          Smoking cessation

–          AREDS antioxidants and zinc supplements (more effective for extensive dry AMD)

Treatment:

–          Smoking cessation

–          AREDS antioxidants and zinc supplements

–          Anti-VEGF therapy

–          If anti-VEGF therapy does not work consider PDT or thermal laser photocoagulation

Faculty Reviewer: Griffin Jardine, MD

References:

  1. Hyman L. Epidemiology of eye disease in the elderly. Eye (Lond) 1987; 1 ( Pt 2):330.
  2. Bressler NM. Age-related macular degeneration is the leading cause of blindness… JAMA 2004; 291:1900.
  3. Lietman MW. Manual for eye examination and diagnosis. 9th Hoboken, NJ: John Wiley & Sons Inc.; 2017.
  4. Jager RD, Mieler WF, Miller JW. Age-related macular degeneration. N Engl J Med 2008; 358:2606.
  5. Age-Related Eye Disease Study Research Group. A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no. 8. Arch Ophthalmol 2001; 119:1417.
  6. Tan JS, Mitchell P, Kifley A, et al. Smoking and the long-term incidence of age-related macular degeneration: the Blue Mountains Eye Study. Arch Ophthalmol 2007; 125:1089.
  7. Solomon SD, Lindsley K, Vedula SS, et al. Anti-vascular endothelial growth factor for neovascular age-related macular degeneration. Cochrane Database Syst Rev 2014.

Identifier: Moran_CORE_24645