Fluorescein Angiography Versus lndocyanine Green Angiography In The Diagnosis Of Central Serous Chorioretinopathy

Abstract

Central serous chorioretinopathy is a disease which has been known since 1866, with an obscure aetiology until recent years, where different theories have been postufated.

With the advent of ICG dye, it proved superior to FA in visualizing choroidal circulation.

ICG absorbs light in the infrared region of the spectrum (maximal absorption is approximately at 790 nm and fluoresces in the near infrared region with maximal emission approximately at 835 nm); Because of its activity at these longer wavelengths, ICG fluoresces through pigment layers. Also, approximately 98% of ICG is bound to plasma proteins and therefore the dye does not leak from the cnoriocapillaries. This property allows better visualization of the choroidal vessels. On the contrary, fluorescein dye excitation and fluorescence is between 465-525 nm which are blocked by melanin and macular xanthophyll. In addition, sodium fluorescein is 60%-80% bound to plasma albumin so it rapidly leaks from the fenestrated choriocapillaries and produces background fluorescence which further obscures the details of the choroidal vessels. Because of the above factors and former factors mentioned in the review, ICGA is very useful in delineating the choroidal vasculature and the probable pathological factors contributing to the occurrence of CSC much more than FA, and might be useful in the strategy of laser photocoagulation treatment.