OBJECTIVE Multiuse of the G-probe transscleral cyclophotocoagulation (TSCPC) device can lead to contamination. We evaluated the mechanical stability and clinical efficacy of a disposable sterile barrier for the G-probe footplate. METHODS We measured diode laser output with and without the G-probe barrier both before and after cadaver TSCPC (18 shots at 2000 mW for 2000mS). Qualitative analyses of the laser aiming beam were made before each trial in the barrier and nonbarrier state. After each trial, the G-probe barrier was examined for microperforations and footplate for debris and/or damage. Microbiology was taken on the cadaver eye and the G-probe before and after 20 cycles. Histologic analysis after TSCPC with and without barrier was carried out on a cadaver eye. RESULTS Qualitatively, laser focus dispersion was minimized by the G-probe cover. Mean (95% CI) laser output was measured for the nonbarrier, with barrier pre-TSCPC and with barrier post-TSCPC, respectively as 980 mW (899,1061), 1247 mW (1115, 1378), and 1240 mW (1132, 1347). The difference between the nonbarrier and barrier both preTSCPC and postTSCPC was statistically significant (df=2, F=36.26, P<0.01). No perforations in the G-probe barrier were evident and no debris or damage was detected on the G-probe. Pathology was consistent with earlier reports of TSCPC in cadaver eyes. Microbial segregation of the cadaver eye and the G-probe footplate was maintained. CONCLUSIONS The G-probe barrier is an effective and robust method to protect consecutive patients from contamination during TSCPC. Although energy levels were slightly higher in probes with barrier, histologic differences were not evident and the clinical significance of this finding is likely limited.