Indocyanine green angiography - An evaluation of image enhancement for theidentification of occult choroidal neovascular membranes

Purpose: To determine the diagnostic yield of occult choroidal neovasculari zation from examination of nonenhanced digital indocyanine green (ICG) angi ograms versus examination of both nonenhanced and contrast-enhanced angiogr ams. Methods: Fifty consecutive occult choroidal neovascular membranes were exam ined using ICG angiography at the Queen's University Eye Department. These studies were retrospectively reviewed in a masked fashion using the nonenha nced images. A subsequent examination of the same images was then performed using both the nonenhanced and contrast-enhanced images. Each study was gr aded as focal hyperfluorescence, plaque hyperfluorescence, isofluorescence, or hypofluorescence. Results: Of the cases reviewed, only 36% (18/50) of the membranes were well -defined on nonenhanced ICG angiography, compared with 58% (28/50) using im age enhancement in addition to the nonenhanced images. This was a statistic ally significant difference in image definition between the two groups (chi -square test; P < 0.005). Conclusion: Contrast-enhanced angiograms, when used in conjunction with non enhanced ICG images, allowed for a significantly higher diagnostic yield wh en compared with the study of nonenhanced images alone.