Erbium: YAG laser trabecular ablation with a sapphire optical fiber

The purpose of the study was to evaluate the effect of erbium (Er): yttrium aluminum garnet (YAG) laser trabecular ablation with a sapphire optical fiber on outflow facility. After obtaining baseline outflow facility using a computerized differential pressure perfusion system, human cadaver eyes were subjected to Er: YAG laser trabecular ablation using a sapphire optical fiber. Single pulses at varying energy levels (10 to 20 mJ pulse-1) were applied in a nearly contiguous fashion over four clock hours of meshwork. Post-laser outflow facility was then determined utilizing the same perfusion system and histopathologic analysis performed. Of the ten eyes, nine were perfused to steady baseline facility. One eye was excluded from the study because of a leak in our system during the initial perfusion. The mean baseline facility was 0.283+/-0.08 microl min-1 mmHg-1. There was a significant increase in outflow facility after trabecular ablation, with a mean post-laser facility of 0.62+/-0.15 microl min-1 mmHg-1 (P=0.01). Eyes which received a sham treatment showed no increase or a minimal increase in facility. Histopathologic analysis revealed ablation into Schlemm's canal with some thermal damage to the outer wall at all energy levels. Er: YAG laser trabecular ablation with a sapphire fiber is capable of increasing outflow facility in human cadaver eyes.