Age-related macular degeneration – dry

Description

The term age-related maculopathy (ARM) refers to the preclinical form of age-related macular degeneration (AMD), before visual acuity is affected. There may be drusen and pigment abnormalities of the retinal pigment epithelium (RPE) and retina. Dry age-related macular degeneration (AMD) refers to the later stages of the disease, when vision is affected but without neovascular complications, and is also referred to as atrophic or nonexudative AMD. Loss of central vision in AMD occurs following the deposition of material in Bruch’s membrane (drusen), beneath the RPE. Vision is not affected unless there is an associated loss of pigment and atrophy of the RPE, degeneration of the choriocapillaris and photoreceptor atrophy. Ultimately a geographic atrophy may develop.

Symptoms

In the early stages of AMD, patients may note slight distortion(metamorphopsia) or blurring of vision.

Signs, classification, prevalence,
significance, differential diagnosis

See Age-related macular degeneration – classification

Consider also Intraretinal processes such as intraretinal lipid (exudates), retinal emboli and cotton-wool spots (infarcts)

Management

Currently, there are no available therapies for AMD that are proven to restore the patient’s visual acuity. However, some strategies are designed to reduce the risk of progression.

Advice Patients should be encouraged consume fruit on a daily basis and to give up smoking. A recent prospective study of

118 428 people showed a protective role for fruit intake (three or more servings per day) on the risk of neovascular ARM. Several studies have shown that smoking is a risk factor for the development of AMD, possibly due to oxidative stress, the promotion of atherosclerosis or some other mechanism. The patient’s general vascular status should be reviewed, because of possible effects on the choroidal circulation and lipid deposition within Bruch’s membrane. Associations havebeen documented between AMD and systemic conditions such as hypertension, cerebrovascular disease, atherosclerosis and serum cholesterol level.

Oral medication The Age-Related Eye Disease Study (AREDS) research group reported in 2001 that the antioxidants vitamin C (500 mg), vitamin E (400 IU) and P-carotene (15 mg), as well as zinc oxide (80 mg), provided some reduction in the risk of progressing to advanced AMD in patients with intermediate AMD. An effect for patients with mild ARM was not shown. Some studies have suggested that cholesterol-lowering medication is beneficial, but the effect is not considered proven.

Review Patients with AMD may be reviewed annually, but encouraged to attend immediately if signs of reduced vision or distortion are noted. They may be provided with an Amsler (grid) chart for home use to self-assess the vision in each eye for distortion.

Refractive correction or low vision aids Increasing the reading addition is often used as a first step in assisting with reduced acuity in patients with macular degeneration. Other options for low-vision assistance include telescopes, hand magnifiers, increased screen size for television or computer monitors, and closed-circuit television or computer magnification systems.