The Ischemic Index (ISI) is a measure of impaired perfusion associated with retinal vascular disease.
Method: ultra-widefield fluorescein angiography images
Parameters:
(1) total fundus area of the eye is measured in square mm
(2) area of nonperfusion in square mm
ischemic index in percent =
= (area of nonperfusion) / (total fundus area) * 100%
Interpretation:
• The larger the index the greater the degree of ischemia.
