[Indocyanine green enhanced photocoagulation in the pigmented rabbit]

We performed histological studies of rabbit eyes after intravenous administration of indocyanine green (ICG) and fundus endophotocoagulation with diode laser at the wavelength of 810 nm. As continuation of our previous experiments in albino rabbits, we used 10 eyes of 5 pigmented rabbits which more simulate human eyes. We created weak photocoagulation spots 5 to 30 seconds after intravenous ICG, 4 mg/kg. Each photocoagulation lasted 0.2 sec and its irradiation power was averaged 170 mW. One hour after photocoagulation, there were no changes in the inner retinal layers. In the choroid, we observed occlusion of the choriocapillaris, destruction or loss of endothelial cells of large choroidal vessels, and stromal edema. One month after photocoagulation, large choroidal vessels had disappeared. Whole choroidal layers were replaced by fibrous scar tissue. The findings seemed to indicate that ICG enhanced photocoagulation effect can be observed in eyes with pigmented retinal pigment epithelium and that irreversible choroidal damages can be induced throughout the whole thickness of the choroid. The observed choroidal damages were less in intensity than those in albino rabbits.