| There
are two main types of AMD: the "dry" form and the "wet" form, based on the absence
or the presence of abnormal growth of blood vessels under the retina. Most
people with AMD have the dry form.
Currently there is
no proven treatment for the dry type, but the loss of vision tends to be
milder and the disease progression is rather slow.
Approximately 15%
of patients with AMD have the wet form, where there is a growth of abnormal
blood vessels under the retina, which can cause leakage, bleeding, and
scarring, resulting in more rapid and severe vision loss. About 80% of
severe vision loss is due to the wet form as compared to 20% due to the
dry form.
The wet form can
manifest in two types: classic or occult. Over 70% of patients with the
wet form have the occult type. So far, only the classic wet type is treated
with conventional laser photocoagulation to stabilize vision or to limit
the growth of abnormal blood vessels. The remaining majority of patients
with wet AMD cannot be treated with the laser procedure. Also, the current
laser treatment does not improve vision in most treated eyes because the
laser destroys not only the abnormal blood vessel but also the overlying
macula. Better treatment options are obviously needed. |
