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macular degeneration

breakdown of cells in the macula lutea, resulting in a loss of central vision in the affected eye; peripheral vision is not affected. There are several varieties; most appear in persons 50 to 60 years of age (age-related macular degeneration), but one variety is congenital and is seen in younger people (stargardt's disease or Stargardt's macular degeneration). In about 75 per cent of cases the cause is not known, and nothing can be done to prevent, arrest, or reverse the process.
Patient Care. Since a large majority of cases of macular degeneration cannot be arrested or treated, care is aimed at making the most of the vision that the patient has. The condition does not progress to total blindness and usually is self-limiting. The inability to perceive detail can be compensated for in part by using large-type books and magazines and a magnifying lens for reading, and having adequate lighting whenever detail work is necessary.

Patients with macular degeneration are given a sheet of paper on which is printed a grid of horizontal and vertical lines. They are instructed to look at this grid daily and note whether there is any change in distortion of lines in the center of vision. This same technique can be used as a screening test to evaluate central vision. However, seeing distorted lines in the grid is not necessarily symptomatic of macular degeneration. Further examination by an ophthalmologist is necessary for a definitive diagnosis.
Grid for evaluating macular degeneration.
age-related macular degeneration (ARMD) a type having its onset between the ages of 50 and 60, the leading cause of blindness in persons over the age of 65. There are two main types, involutional and exudative age-related macular degeneration.

The involutional (dry or non-exudative) type accounts for 90 per cent of cases and is characterized by the gradual wearing out of the cells in the retinal pigment epithelium, resulting in a slow, progressive loss of central vision. Although visual acuity loss usually does not progress beyond the 20/200 level, this is a significant disability. Treatment is not generally available.

The exudative (neovascular or wet) type is characterized by the growth of a neovascular membrane within or very close to the macula, resulting in distorted and blurred vision. The vision loss from this type of macular degeneration may be only of hand movements. Laser photocoagulation of this form of macular degeneration is aimed at destroying the neovascular membrane; if diagnosed and treated very early when the membrane is small, significant loss of central vision may be avoided.
Patient Care. Health care providers can be of great help for early diagnosis of this devastating disease through ongoing patient education programs. After laser treatment, which is performed under a retrobulbar anesthetic, the patient should be instructed to leave the patch in place for at least six hours. Any increase in distortion or blurred vision should be immediately reported and followed up by an urgent outpatient exam. Low vision aids and services can improve quality of life for persons with this disorder.
Stargardt's macular degeneration Stargardt's disease.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


Age-related macular degeneration, see there.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

Age-related macular degeneration (ARMD)

Degeneration of the macula (the central part of the retina where the rods and cones are most dense) that leads to loss of central vision in people over 60.
Mentioned in: Cataract Surgery
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
In other words, the mean increase in drusen number in patients with drusiform dry ARMD was 4.17 drusen for the right eye and 5.05 drusen for the left eye over 2-year period (Table 1).
Genetic Background of ARMD. Single-nucleotide polymorphisms (SNPs), mutations of mitochondrial DNA (mtDNA), and micro-RNAs (mi-RNAs) consist of the genetic background of ARMD.
In a recent study, Dutch scientist found that study participants that ate more fruits, vegetables and whole grains lowered this risk of ARMD by 35% compared to those that did not.
They found that study participants who ate the most fruits, vegetables and whole grains lowered their risk of ARMD by 35% compared to those who ate the least.
Though everyone over 40 should have an ophthalmologic exam every year or 2, many patients that may routinely see their primary care physician will not consult an ophthalmologist until a problem manifests (see Demographics of ARMD).
Patients carrying a diagnosis of cataracts, glaucoma, ARMD, or diabetic retinopathy were included.
Among persons with diagnosed ARMD, only 1 percent was selected for the ARMD sample based on diagnoses recorded before 1991.
ARMD sneaks up on its victims, robbing them of precious vision a fraction at a time.
* RESULTS Patients with no ARMD (category 1) and mild or borderline ARMD (category 2) did not benefit from antioxidant and/or zinc supplementation.
Fortunately, peripheral vision is spared, so ARMD doesn't lead to complete blindness.
Vision loss from ARMD appears to be triggered, at least in part, by cumulative oxidative damage to the eyes, a reason why ARMD occurs mostly in older people.