Effects of indocyanine green dye enhanced diode laser photocoagulation in non-pigmented rabbit eyes

Dye enhanced photocoagulation using indocyanine green (ICG) and diode laser has recently been introduced for occlusion of the choroidal neovascular tissue of age-related maculopathy. However, the effects of photocoagulation generated only by dye enhancement have not yet been studied. To discover the threshold amount of ICG for the minimum effect of photocoagulation, various photocoagulation parameters were tried in the fundus of albino rabbit. That is to say, ICG dosage laser power and exposure time were varied at the range of 0.5 mg to 14.0 mg/Kg, 80 to 500 mW and 0.2 or 1.0 sec, respectively. Histopathologic evaluation revealed that the effect of the enhanced photocoagulation was more marked in the choroid than in the retina, and was particularly noticeable in the large vessels in the deep layer of the choroid, even in lower threshold lesions. In clinical application, we should take into consideration the excessive reaction in the choroid.