Contact transscleral retinopexy using a sapphire crystal probe.

To examine the laser-tissue interactions for contact transscleral irradiation, argon and CW Nd:YAG light was delivered through a synthetic sapphire crystal which was held in direct conjunctival contact perpendicular to the peripheral retina. The threshold for retinal whitening was 0.5 J in the rabbit, 1.0-1.5 J in the monkey, and 1.0-4.0 J in human eyes. Histologic examination of the acute injury and at 2 days, 1, 3, 6, and 12 weeks, showed coagulative lesions centered around the pigmented layers in the rabbit. While severe chorioretinal disruption and hemorrhage did occur depending on species, energy level, and probe location, no scleral perforation was noted at any setting. These preliminary studies suggest that transscleral contact lasers may be used safely in clinical situations where selective ablation of the peripheral retina or pigmented tissues is the primary objective.