HISTOPATHOLOGIC EXAMINATION OF VASCULAR PATTERNS IN SUBFOVEAL NEOVASCULAR MEMBRANES

Background: Subfoveal neovascular membranes cause significant visual l oss in age-related macular degeneration (AMD) and the ocular histoplas mosis syndrome. The frequency of post-laser treatment persistence or r ecurrence of subfoveal membranes in AMD is as high as 51%. The reason for the high incidence of failure after laser treatment is unknown. Th e authors performed a histopathologic study of subfoveal membranes to determine the distribution of blood vessels within the neovascular com plex, and to see if the blood vessel pattern would provide insight int o the reason for laser treatment failure. Methods: The authors used li ght microscopy to examine serial sections of subfoveal membranes from six patients (4 with AMD, 2 with the ocular histoplasmosis syndrome). The data from this examination were used to create detailed two-dimens ional vascular maps of each membrane. Results: The authors found that subfoveal membranes from patients with AMD and the ocular histoplasmos is syndrome, whether occurring de novo or after laser treatment, have a nonuniform distribution of blood vessels, and that large areas which include the membrane margin may be avascular. Conclusions: Using curr ent laser treatment protocols, it is likely that avascular or poorly p erfused peripheral areas of the neovascular complex would be left untr eated after laser photocoagulation. Partial treatment of the neovascul ar complex may contribute to the high rate of post-laser treatment per sistence or recurrence of subfoveal membranes.