Evaluation of the human choroidal melanoma rabbit model for studying microcirculation patterns with confocal ICG and histology

The aim of this study was to develop consistently focal elevated choroidal masses of human choroidal melanoma in immunosuppressed rabbits and to corre late the visualization of prognostically significant microcirculation patte rns from confocal indocyanine green angiography with histologic microcircul ation patterns. A human choroidal melanoma cell line (OCM1) was implanted i n the choroid of 40 rabbit eyes using three different techniques: transscle ral choroidal injection of a cell suspension, injection of a cell suspensio n in a surgically induced cyclodialysis cleft, and implantation of solid tu mor fragments in a surgically induced cyclodialysis cleft. The rabbits were immunosuppressed with daily injections of Cyclosporin A to prevent host ve rsus graft reaction. The eyes were studied weekly with indirect ophthalmosc opy and fundus photography to monitor tumor growth and indocyanine green an giography using a confocal scanning laser ophthalmoscope to identify microc irculation patterns in vivo and correlate these findings with the histologi c demonstration of tumor microcirculation patterns. A tumor mass was identi fied by indirect ophthalmoscopy in 16 of the 40 implanted rabbit eyes (40 % ). Each of these tumors was confirmed histologically to represent a focal e levated choroidal mass. All 16 elevated choroidal masses grow in eyes in wh ich solid tumor fragments were implanted. In total, a melanoma was identifi ed histologically in 28 of the implanted 40 eyes (70%). In addition to the 16 eyes where the melanoma appeared as a focal elevated choroidal mass, 4 e yes contained a focal elevated mass in the sclera and 8 eyes contained a fl at choroidal tumor. Histologically, microcirculation patterns were identifi ed only in the 16 eyes with focal elevated choroidal masses. Confocal indoc yanine green angiography imaged microcirculation patterns in 13 of these 16 eyes (81%). The surgical implantation of small solid fragments of human ch oroidal melanoma in immunosuppressed rabbit eyes provides the best method t o consistently obtain focal elevated choroidal masses. These focal elevated choroidal masses resemble booth the localization and the growth pattern of choroidal melanomas in humans. In addition, they also contain microcircula tion patterns similar to those seen in humans that are detectable with conf ocal indocyanine green angiography. The use of indocyanine green angiograph y with this animal model may be especially useful in designing and evaluati ng anti-microcirculation treatments directed at uveal melanoma. (C) 1999 Ac ademic Press.