Transscleral and indirect ophthalmoscope diode laser retinal photocoagulation: experimental quantification of the therapeutic range for their application in the treatment of retinopathy of prematurity.

Laser indirect ophthalmoscope (LIO) photocoagulation and transscleral photocoagulation through the conjunctiva and subconjunctiva were performed in the fundus of chinchilla gray rabbits using various exposure times and powers, and the thresholds for retinal blanching and choroidal hemorrhage were determined. The therapeutic range was described for both applications as the ratio between energy values to produce grayish white lesions and hemorrhage at 50% probability. The therapeutic range appeared to remain almost constant with different exposure times. The mean ratio with LIO was 3.2 +/- 0.28, similar to that with slit-lamp delivery reported in our previous study. The mean ratio with transscleral photocoagulation through the conjunctiva and subconjunctiva were 2.48 +/- 0.28 and 2.38 +/- 0.26, respectively. The variability of LIO appeared to be a little lower than with transscleral photocoagulation. There was no significant difference between the variability with transscleral photocoagulation through the conjunctiva and subconjunctiva.