macular degeneration (ARMD) is the most common cause
of vision loss in those over 50s and its prevalence
increases with age. It is caused by degeneration
of the macula, the central, and most sensitive part of
the retina at the back of the eye.
The macula is the part of the retina that
allows the eye to see fine details at the center of
the field of vision. Degeneration results from a
partial breakdown of the retinal pigment epithelium
The RPE is the insulating layer between the retina and
the choroid (the layer of blood vessels behind the
retina). The RPE acts as a selective filter to
determine what nutrients reach the retina from the
choroid. Many components of blood are harmful to the
retina and are kept away from the retina by normal
Breakdown of the RPE interferes with the metabolism of
the retina, causing thinning of the retina (the "dry"
phase of macular degeneration). These harmful elements
may also promote new blood vessel formation and fluid
leakage (the "wet" phase of macular degeneration).
This disorder results in the loss of central vision
only -- peripheral fields are always maintained.
Although loss of ability to read and drive may be
caused by macular degeneration, the disease does not
lead to complete blindness.
The disease becomes increasingly common amongst people
in each succeeding decade over 50. By age 75, almost
15% of people have this condition. Other risk factors
are family history, cigarette smoking, and being
|This is an example of
what a patient with advanced macular
degeneration might see.