Encyclopedia of Health and Medicine

A
age-related macular degeneration (ARMD) A
progressive condition that results in the gradual
deterioration of the macula, the portion of the
RETINA that provides the ability to see fine detail,
and loss of vision from the center of the field of
vision. ARMD is the leading cause of VISION IMPAIR-
MENT, resulting in functional limitations and legal
blindness in people over the age of 50. ARMD
develops when the retina’s BLOOD supply diminishes.
The macula’s high concentration of cones,
the cells responsible for color and fine detail
vision, makes it especially vulnerable to damage
and its cells begin to die. The death of the cells
result in diminished vision. ARMD may affect one
eye at first, though nearly always affects both eyes
as it progresses.
There are two forms of ARMD, atrophic (commonly
known as dry) and neovascular (commonly
known as wet). All ARMD begins as the atrophic
form, in which the nourishing outer layer of the
retina withers, or atrophies. Approximately 90
percent of ARMD remains in this form and progresses
slowly. In the remaining 10 percent, new
blood vessels begin to grow erratically within the
choroid, the blood-rich membrane that nourishes
the retina. These blood vessels are thin and fragile,
and bleed easily. The resulting hemorrhages cause
the retina to swell, distorting the macula and
accelerating the loss of cells.
Symptoms and Diagnostic Path
ARMD begins insidiously and people tend to
attribute early symptoms to the normal changes of
aging. Early symptoms include
• blurring of words when reading
• “missing pieces” in the field of vision, such as
parts of words or gaps in the appearance of
lines or objects
• the need for increased light to perform tasks
that require close vision
• faded colors
• tendency to look slightly to the side of objects
to see them clearly
• distorted or wavy lines on linear objects such as
signs, doorways, and railings (suggests wet
ARMD)
As the macular degeneration progresses, a blind
spot in the center of vision becomes apparent and
enlarges. Wet ARMD progresses far more rapidly
than dry ARMD. A simple screening test called the
AMSLER GRID can show the gaps in vision that
occur with either form of ARMD. The ophthalmologist
uses further procedures, such as OPHTHAL-
MOSCOPY and SLIT LAMP EXAMINATION, to visualize the
retina and macula and determine which form of
ARMD is present and how extensive the damage.
The ophthalmologist looks for signs of exudation
(swelling of the tissue that oozes fluid) that suggests
wet ARMD, and for drusen (spots of depigmentation
on the macula that signal the loss of
retinal cells). For wet ARMD, the ophthalmologist
may perform a diagnostic procedure called fluorescein
angiography, in which the ophthalmologist
injects fluorescein dye into a VEIN and then takes
photographs of the retina as the dye flows
through its blood vessels.
Treatment Options
Treatment options for ARMD are limited, and at
this time there really are no treatments for dry
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