Classification of choroidal neovascularization by digital indocyanine green videoangiography

Abstract

Purpose: The majority of patients with exudative maculopathy due to age-related macular degeneration present with poorly defined or occult choroidal neovascularization (CNV) that cannot be imaged adequately by fluorescein angiography. Digital indocyanine green (ICG) videoangiography is a new technique that allows enhanced imaging of these poorly defined or occult vessels. The authors studied 1000 consecutive cases of occult CNV using digital ICG angiography to describe the various types of neovascularization observed by this technique and to determine the frequency and natural history of the various lesions.

Materials and methods: Digital ICG videoangiography was performed as described previously on 1000 consecutive eyes with occult CNV by fluorescein angiography.

Results: One thousand consecutive eyes with occult CNV by fluorescein angiography were imaged using digital ICG videoangiography. Three morphologic types of CNV were noted by ICG videoangiography, which included focal spots, plaques (well-defined or poorly defined), and combination lesions (in which both focal spots and plaques are noted). Combination lesions can be subdivided into marginal spots (focal spots at the edge of plaques of neovascularization), overlying spots (hot spots overlying plaques of neovascularization), or remote spots (a focal spot remote from a plaque of neovascularization). The relative frequency of these lesions was as follows: there were 283 cases (29%) of focal spots; 597 cases (61%) of plaques, consisting of 265 cases (27%) of well-defined plaques and 332 cases (34%) of poorly defined plaques; and 84 cases (8%) of combination lesions, consisting of 35 cases (3%) of marginal spots, 37 cases (4%) of overlying spots, and 12 cases (1%) of remote spots. In seven additional cases (1%), a mixture of the above lesions was noted. In 13 additional eyes (1%), no lesions were noted on the ICG angiogram. The studies of 16 eyes were unreadable or unobtainable.

Conclusions: There are three types of CNV that can be observed by digital ICG videoangiography. Plaques are the most common type and have a poor natural history. Focal spots or hot spots are the next most frequently seen lesion and can potentially be treated by ICG-guided laser photocoagulation. Combination lesions, in which both focal spots and plaques are present, are rare. This study of 1000 consecutive cases of eyes with occult neovascularization that were imaged with digital ICG videoangiography serves to classify the various types of neovascularization observed by this technique. Digital ICG videoangiography is an important tool in better delineating eyes with occult CNV. Future studies are necessary to validate our findings.