3
Types and progress
The interaction of oxygen within our body releases certain harmful
substances that are called free radicals. These can cause a wide range
of diseases elsewhere in the body, and also seems to play a vital role
in the pathogenesis of ARMD.
There are two types of age related macular degeneration:
Dry
macular
degeneration and
Wet
macular degeneration.
Dry ARMD can follow a chronic progression for many years with
few or no symptoms. About 10 to 15% of patients with dry ARMD
will develop wet ARMD, with sudden symptoms of deterioration of
vision.
In the initial, early stage of dry ARMD, the characteristic sign is the
appearance of yellow deposits containing lipids and proteins that
are called
Drusen
. The patient at this stage is usually asymptomatic.
Over time, these deposits rise in number and volume and cause
complications to the central vision.
In more advanced forms of Dry ARMD, the retina appears with well-
defined areas of atrophy which can also be defined as
geographical
atrophy
due to the macula appearance as a geographical map.
ARMD dry type
Geographic Atrophy.
Left: Color photograph of the retina
Right: Fundus autofluorescence photography, i.e. with the use of
fluorescence-angiography filters before the injection of fluorescence dye
