Indocyanine green angiography and histopathology of choroidal neovascular membrane in age-related macular degeneration

Purpose: Histopathological investigation of the choroidal neovascular membr ane (CNM) in age-related macular degeneration (AMD) patients who showed var ious findings in indocyanine green angiography (IA). Methods: Before surgery, 20 eyes of 20 patients were classified into four t ypes based on IA findings (Type I: both early and late phase hyperfluoresce nce; Type II: hyperfluorescence only in the early phase; Type UI: hyperfluo rescence only in the late phase, Type IV: virtually no hyperfluorescence in any phase). Seventeen surgically excised specimens stained with hematoxyli n-eosin and azan, were examined by light microscopy. Three other specimens were examined by electron microscopy. Results: Type I membrane showed many vascular channels not present in the s urrounding retinal pigment epithelium (RPE) cells, and little fibrous tissu e. Type II membrane had many vascular channels but RPE cells surrounded the CNM. Type III membrane showed few vascular channels and RPE cell prolifera tion. Type IV membrane showed dense fibrous tissue. Conclusion: The IA findings in AMD agreed with the CNM membrane structure i n regard to the number of vascular channels, maturity of vessels, the exten t of envelopment of RPE cells and the amount of fibrous tissue. (C) 2000 Ja panese Ophthalmological Society.