Comparison of techniques for transscleral diode photocoagulation in the rabbit

Purpose: To assess the optimum probe design and treatment parameters for transscleral diode laser retinopexy. Methods: Transscleral diode photocoagulation was performed on the eyes of Dutch-belted rabbits using three different transscleral probes: a straight, 400-μm diameter probe; a prism-tipped 400-μm diameter probe; and a prism-tipped 900-μm diameter probe. Results: Transscleral diode photocoagulation with all three probe types was an effective method of ablating the retina and creating chorioretinal adhesions. Both the burn diameter and the mean radiant output energy requirement increased as the burn duration and probe aperture diameter was increased. Explosive retinal holes were encountered in 12% of the burns created with the straight probe. The use of the prism-tipped probes significantly reduced the incidence of retinal holes to <4% (P < 0.005). Histopathologically, all burns were grade III in intensity with severe choroidal injury. In many of the burns, there was histopathologic evidence of thermal injury to the inner sclera. The frequency of these inner scleral changes was reduced with a long burn duration (5 seconds). Conclusion: This study confirms that diode transscleral photocoagulation is a feasible method of thermal retinopexy. The use of the prism-tipped probes and long duration burns resulted in the fewest adverse reactions.