[Quantification of indocyanine-green enhancement of diode laser photocoagulation]

The enhancement by indocyanine-green (ICG) of diode laser photocoagulation was quantified. Since ICG concentration in blood increases and decreases rapidly after a single injection, it is difficult to quantify the exact enhancing effect of ICG. A steady-state plasma concentration (about 30 micrograms/ml) of ICG was achieved by injection of 2.5 mg/kg of ICG followed by continuous injection of 0.45 micrograms/kg/min of ICG. The threshold energy values to obtain grayish white retinal burn or choriocapillary occlusion were evaluated at this steady concentration of ICG, and compared with the values in the absence of ICG. The use of ICG decreased the energy values 7% for retinal burn and 8% for choriocapillary occlusion. Although the total dosage of ICG during the continuous injection was high, the enhancement of retinal burn and choriocapillary occlusion was small.