Indocyanine green angiography features in toxoplasmic retinochoroiditis

Background: Indocyanine green (ICG) angiography detects the infrared fluorescence of ICG through the retinal pigment epithelium, providing visualization of the choroidal vascular network. The aim of this study was to analyze ICG angiographic features in toxoplasmic retinochoroiditis. Methods: Indocyanine green angiography was performed according to a standard uveitis angiographic protocol in 28 consecutive patients diagnosed with acute toxoplasmic retinochoroiditis. Indocyanine green angiographic data were compared with fundus color photographs and fluorescein angiography (FA). Evolution of ICG angiographic signs after therapy (pyrimethamine and sulfadiazine with or without a tapering course of oral corticosteroids) was further analyzed. Results: The main focus of retinochoroiditis was hypofluorescent at all phases of the ICG angiogram in 25/28 cases (89%), but late phase (35-45 minutes) ICG hyperfluorescence was seen in three cases, all of which had very superficial retinal involvement. The most striking features, however, were multiple hypofluorescent satellite dark dots (SDD), present in 21/28 cases (75%). in 17 of these 21 patients, hypofluorescent areas were silent on FA and fundus examination. After therapy, SDD disappeared from most of the cases. Furthermore, the hypofluorescence under the main lesion was markedly reduced or disappeared in some cases. Conclusions: Indocyanine green angiography showed that toxoplasmic retinochoroiditis is a more widespread process than is clinically suspected because it extends beyond the visible lesions. Indocyanine green angiography appears useful in assessing the extent of choroidal involvement and the evolution of lesions. It might become an important follow-up parameter and also may give new insights into the pathophysiology of this disease. Based on the findings gathered so far, ICG angiography appears indicated in the workup and management of toxoplasmic retinochoroiditis.