Transscleral infrared laser for retinal ablation without retinal visualization in an experimental model.

PURPOSE: To investigate whether transscleral diode laser can create retinal photocoagulation reliably without creating retinal holes under conditions simulating opaque media.

METHODS

In New Zealand pigmented rabbits, optimal infrared diode laser power settings were determined, and transscleral retinal photocoagulation was then applied 4 mm and 6 mm from the limbus without retinal visualization. Transscleral testing was done using retina and cyclophotocoagulation probes placed directly on the sclera, on conjunctiva, and on silicone scleral buckles.

RESULTS

A retina probe placed on the sclera achieved moderate retinal photocoagulation intensity in 75% of spots 4 mm from the limbus and in 50% of spots 6 mm from the limbus. Retinal holes were only formed when using the transscleral cyclophotocoagulation (TSCPC) probe. An association between burn intensity and the presence of conjunctiva was seen for the TSCPC probe (P = 0.0001) but not for the retina probe (P = 0.125). Photocoagulation spots did not exceed moderate intensity through any of the silicone scleral buckles tested.

CONCLUSIONS

Transscleral infrared photocoagulation applied without retinal visualization did not cause retinal hole formation with a retina probe placed directly on conjunctiva, sclera, or scleral buckle material. A TSCPC probe created retinal holes when placed directly on sclera. A decrease in power was required for all treatments closer to the limbus.