The authors undertook an investigation to evaluate the efficacy and complications of performing internal sclerostomy with the synthetic sapphire contact neodymium:YAG (Nd:YAG) laser compared with standard external thermal sclerostomy. Fifteen rabbits underwent internal laser sclerostomy in one eye; 12 additional rabbits underwent a standard external thermal sclerostomy in one eye. The fellow eyes served as controls. The differences between the groups in duration of functional blebs and pressure reduction were statistically significant (P = 0.034 and 0.0013, respectively). The evaluation of success (as determined by a pressure reduction greater than 3 mmHg between both eyes after digital pressure) using life-survival analysis indicated that the success rate of the laser-treated group was significantly different from the standard surgical group (P = 0.002). Histologically, there was less inflammation in the laser-treated group 2 days postoperatively. The complications of the laser treatment include focal injury to the overlying cornea, adjacent iris stroma, and lens.