Nonexudative (Dry) Age-Related Macular Degeneration (AMD) Clinical Presentation

Updated: Aug 16, 2018
  • Author: Raj K Maturi, MD; Chief Editor: Andrew A Dahl, MD, FACS  more...
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Presentation

History

Patients with age-related macular degeneration (AMD or ARMD) usually report a family history of decreased vision late in life.

They often report difficulty with night vision and with changing light conditions. Specifically, patients report changes in Amsler grid self-evaluation and trouble with reading.

Commonly, AMD patients report visual fluctuation (ie, days when vision is poor and other days when it appears improved).

Patients report difficulty with reading and making out faces.

Metamorphopsia is not a major complaint, but it may be present as the atrophy slowly progresses.

An association between AMD and Alzheimer disease has been reported. [14]

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Physical

Funduscopic examination in age-related macular degeneration (AMD or ARMD) is significant for drusen in the early stages of disease. These drusen usually are confluent with significant pigment changes and accumulation of pigment in the posterior pole. RPE often appears atrophic with an easier visualization of the underlying choroidal plexus.

In advanced stages of dry ARD, these focal islands of atrophy coalesce and form large zones of atrophy with severely affected vision.

Signs of choroidal neovascularization include RPE elevation, exudate, or subretinal fluid. The presence of these symptoms may indicate that neovascularization is occurring and that fluorescein angiography may be indicated to evaluate the retina.

The periphery of patients with ARMD often has areas of drusen, as well as RPE mottling and atrophy.

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Causes

Oxidative stress is believed to play a major role in the pathogenesis of age-related macular degeneration (AMD or ARMD) because of combined exposures of the retina to light and oxygen. Additionally, AMD is now widely accepted as a genetically inherited disorder with late onset.

Groundbreaking studies in the genetics of AMD have changed the way in which most specialists perceive the disease. Specifically, a majority of the risk of developing AMD is determined by variations in 3 specific genes, as follows:

  • CFH gene (chromosome 1)

  • BF (complement factor B) gene and C2 (complement component 2) gene (chromosome 6)

  • LOC gene (chromosome 10)

Maller and others showed that polymorphisms in the above 3 genes independently raise the risk of AMD. [15] The above genetic factors contribute to approximately 50% of the sibling risk of developing AMD.

  • Smoking and a higher body mass index are 2 of the most common other environmental factors that contribute independently to the increase in the risk of developing AMD. Smoking has been clearly identified as increasing the risk of AMD by 2 times.

  • Large studies have not shown hypertension or heart disease to increase the odds of developing AMD.

  • Serum lipids were extensively studied regarding their relationship with AMD in the National Eye Institute–sponsored AREDS. One report suggests dietary total omega-3 long-chain polyunsaturated fatty acid (LCPUFA) intake was inversely associated with the development of neovascular AMD (although not nonexudative AMD). [16] Similarly, individuals with higher fish consumption had a slightly lower incidence of developing neovascular AMD.

  • A study looking at whether the regular consumption of omega-3 fatty acids and fish may affect the onset of AMD in women found that incidence of the disease was significantly decreased among women who ate 1 or more servings of fish per week. [17]

  • Studying twins with AMD, Seddon and others arrived at some interesting conclusions. [18] Current cigarette smoking increased the risk of developing AMD by 1.9-fold, and past smoking still increased the risk by 1.7-fold. Increased consumption of fish (>2 servings of fish per week) and a higher intake of omega-3 fatty acids both were protective and reduced the odds of developing AMD by 0.55-fold.

These studies have generally been performed in individuals from the United States of European descent. Thus, the results may not apply to individuals of other races.

Blue light emitted from device screens (eg, smartphones, laptops) also causes vision damage and hastens blindness. Ratnayake et al (2018) found that blue light interacts with retinal, resulting in creation of toxic molecules within photoreceptor and nonphotoreceptor cells, which can cause macular degeneration. [19]

Patients with glaucoma should be asked about cognitive status, since an association between Alzheimer disease and glaucoma has been found. [14]

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Complications

The major complication of dry age-related macular degeneration (AMD or ARMD) is the conversion to wet (or exudative/neovascular) AMD.

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