Wet AMD
AMD is classified into two types: dry AMD and wet AMD (also known as
exudative or neovascular). Wet AMD only accounts for about ten per
cent of cases, but it progresses more rapidly and can be more
damaging.
What Happens
Wet AMD occurs when abnormal blood vessels begin to grow under the
macula (the central part of the retina). These new blood vessels
leak fluid or blood. When the fluid or blood begins to accumulate in
the macula, light-sensing cone cells degenerate and die. Damage to
the macula occurs rapidly, sometimes within months, resulting in
blurred or even lost central vision. For a more detailed look at how
wet AMD affects the eye, take the AMD Challenge.
Vision loss resulting from wet AMD in one eye may not cause
noticeable changes to overall vision, at least initially. People may
still be able to drive, read and see fine details with the eye that
still sees clearly.
Illustration of a normal macula versus macula with wet AMD
Symptoms
A common early symptom of wet AMD is that straight lines appear
wavy. People who notice this condition or other changes are strongly
encouraged to contact an eye care professional immediately for a
comprehensive dilated eye exam. Early detection can go a long way to
preserving your vision when you have wet AMD, so a prompt diagnosis
is important.
In addition to straight lines appearing wavy, people with wet AMD
also tend to see a dark spot or spots as a result of the blood or
fluid under the macula. About 43 per cent of people with wet AMD in
one eye progress to wet AMD in both eyes within five years.
Types of Wet AMD
There are three different subtypes of wet AMD, and they are
classified based on the extent of the abnormal blood vessels in the
eye. The classifications are: predominantly classic, minimally
classic, and occult.
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Predominantly Classic : This subtype accounts for approximately 25
per cent of wet AMD cases. Studies suggest that this subtype leads
to more rapid vision loss than the other subtypes. Lesions (cuts or
injuries in the macula) are well defined.
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Minimally Classic: This subtype has a less rapid rate of vision
loss than the predominantly classic subtype.
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Occult: In the occult subtype the lesions are not well defined,
and they have less leakage than the classic subtypes. This subtype
generally has a less rapid rate of vision loss than predominantly
classic, and together with the minimally classic subtype, accounts
for approximately 75 per cent of wet AMD cases.