Ophthalmic Diagnostic Photography
Fluorescein Angiography
A contrast medium called Sodium Fluorescein is injected into a vein in
the arm. The dye travels quickly through the body's circulatory system,
and is photographed with black and white film it travels through the eye.
The same camera which is used for fundus photography is employed for this
procedure. Two special filters are used to limit the image to the color
of light being emitted from the fluorescent dye.
About twelve seconds after the injection, the dye appears in the arteries
of the retina. Over a two to five second period, the dye travels through
the very small vessels, or capillaries, and fills the veins. Ten minutes
after the injection, the dye has mostly evacuated from the eye, having
stained the optic nerve head.
Fluorescein angiogram of photographer, Stefani Karakas
taken by Ray Northway
This normal progression of dye is interrupted by many diseases of
the choroid, retina, and retinal vasculature. A fluorescein angiogram
of a patient with ocular complications due to diabetes (diabetic retinopathy)
reveals vascular irregularities when compared with the normal angiogram.
Fluorescein angiography is a test which helps in the differentiation
of retinal disease and is used to determine if laser treatment of the
retina is warranted. The Diagnostic Photography Unit performs about
300 fluorescein angiograms per month.
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