Biomedical Engineering Reference
In-Depth Information
Fig. 58 A Kowa Genesis-D
®
fundus camera
Fluorescein angiography is used to evaluate the vascular integrity of
the intraocular arteriolar and venous vasculature. While it is most
commonly used for examination of the retinal and choroidal ves-
sels, it can be applied to iris vasculature as well. It is most frequently
used in toxicology studies to evaluate a compounds effect on neo-
vascularization. It has been applied to various laboratory animals
with 10 % fluorescein most commonly used, but with the use of
indocyanine green also described [
61
,
82
,
108
-
117
].
The technique of fluorescein angiography requires sedation or
anesthesia and pupil dilation [
115
]. The excitable compound, fluo-
rescein, is injected intravenously and a series of timed images of the
tissue of interest (chorioretinal, iris) are obtained. Complications
associated with fluorescein injection may include extravasation and
tissue irritation, vomiting, and anyphylaxis. An excitation filter
(490 nm) and a barrier filter (520-520 nm) must be used on a fundus
camera that is capable of taking multiple, rapid sequenced images.
The Kowa Genesis-Df is designed for fluorescein angiography and is
portable. Prior to injection a baseline color image is obtained and
then sequential black and white images are taken every 20 s. As the
fluorescein fills the chorioretinal vasculature various phases of vascular
filling are described. They include the prearteriolar, retinal arteriolar,
capillary, early venous, late venous, and recirculation. Abnormalities
noted on fluorescein angiography may include vascular anomalies
(aneurysms, neovascularization), blocked fluorescence, leakage of
fluorescein, hypofluorescence, and hyperfluorescence.
3.5 Fluorescein
Angiography
