Age-related macular degeneration (ARMD) is a degenerative
condition of the macula (the central retina). It is one of the most
common causes of vision loss in the United Kingdom in those 50 or
older, and its prevalence increases with age. AMD is caused by hardening
of the arteries that nourish the retina. This deprives the sensitive
retinal tissue of oxygen and nutrients that it needs to function
and thrive. As a result, the central vision deteriorates.
Macular degeneration varies widely in severity. In the worst cases,
it causes a complete loss of central vision, making reading or driving
impossible. For others, it may only cause slight distortion. Fortunately,
macular degeneration does not cause total blindness since it does
not affect the peripheral vision.
AMD is classified as either wet (neovascular) or dry (non-neovascular).
About 10% of patients who suffer from macular degeneration have
wet AMD. This type occurs when new vessels form to improve the blood
supply to oxygen-deprived retinal tissue. However, the new vessels
are very delicate and break easily, causing bleeding and damage
to surrounding tissue.
Patients with wet macular degeneration develop new blood vessels
under the retina. This causes hemorrhage, swelling, and scar tissue
but it can be treated with laser in some cases.
Dry macular degeneration, although more common,
typically results in a less severe, more gradual loss of vision.
The dry type is much more common and is characterized by drusen
and loss of pigment in the retina. Drusen are small, yellowish deposits
that form within the layers of the retina.
Macular degeneration may be caused by variety of factors. Genetics,
age, nutrition, smoking, and sunlight exposure may all play a role. |