الفهرس 
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Abstract
Indocyanine green (ICG) dye is a tricarbocyanine water soluble dye
with a molecular weight of 775. It binds almost totally (98%) to plasma
proteins.
It has peak absorption at 805 nm, and fluorescence peak (emission)
at 835 run, in the near infrared (IR) portion of the spectrum. The ICG dye
has potential advantages over fluorescein sodium for ophthalmic
angiography.
First, being active m the IR range, it penetrates through nonnxal
and abnormal obstacles such as pigments, haemorrhages, and eudates.
Second, being totally, bound to plasma proteins, it shows relatively
slo~v leakage from the fenestrated normal and abnormal choroidal
vasculature.
These allow enhanced imaging of the choroid and its pathological
changes. In contrast the fluorescein which has its peak absorption (465nm)
and emission (525 nm) in the visible portion of the spectrum, and is only
partially protein bound (60-80 %).
Choroidal angiography usmg ICG was initially described in the
earl v 1970’s. However visualization of the choroidal vasculature using
ICG- angiography failed to gain a wide spread clinical use in the past. This
because of low sensitivity ofIR films, poor molecular fluorescence of the
dye which is 4% of the fluorescein, and insufficient light in the near IR
range.
___________ C’ll SUMMARY f0 _
In the last few years developing recent technical advances in
unagmg technologies allowing good visualization of the choroidal
pathology. This include the usc of videoangiography technique, the
incorporation of a digital computer system and scanning laser
ophthalmoscope.
ICG angiography allows study a varieties of choroidal
abnormalities, such as congenital, ischaemic, inflammatory neovascular
and degenerative disorders.
As the absorption spectrum of leG is similar to the emISSIOn
spectrum of the diode laser. Therefore, it may provide a dye enhanced for
IR laser photocagulation therapy. This help selective neovascular closure
with relative sparing of neighbouring neurosensory retina.