Evaluation of diode endoscopic cyclophotocoagulation in bovine cadaver eyes.

Abstract

OBJECTIVE: To evaluate the anterior chamber approach and energy levels for endoscopic cyclophotocoagulation (ECPC) and assess ECPC-induced tissue damage in phakic eyes of bovine cadavers. SAMPLE: 12 bovine cadaver eyes. PROCEDURES: Angle of reach was measured in 6 eyes following placement of a curved endoscopic probe through multiple corneal incisions. In another 6 eyes, each ocular quadrant underwent ECPC at 1 of 3 energy levels (0.75, 0.90, and 1.05 J) or remained untreated. Visible effects on tissues (whitening and contraction of ciliary processes) were scored (scale of 0 [no effects] to 6 [severe effects]), and severity and extent of histologic damage to the pigmented and nonpigmented ciliary epithelium and fibromuscular stroma were each scored (scale of 0 [no effect] to 3 [severe effect]) and summed for each quadrant. Overall mean scores for 6 quadrants/treatment were calculated. RESULTS: Mean ± SD combined angle of reach was 148 ± 24° (range, 123 ± 23° [ventromedial] to 174 ± 11° [dorsolateral]). At the 0.75-, 0.90-, and 1.05-J levels, mean visible tissue effect scores were 3.12 ± 0.47, 3.86 ± 0.35, and 4.68 ± 0.58, respectively; mean histologic damage scores were 4.79 ± 1.38 (mild damage), 6.82 ± 1.47 (moderate damage), and 9.37 ± 1.42 (severe damage), respectively. Occasional popping noises (venting of vaporized interstitial water) were heard at the 1.05-J level. CONCLUSIONS AND CLINICAL RELEVANCE: Multiple incisions were necessary to facilitate 360° ECPC treatment in bovine eyes. For ECPC in vivo, the 0.75- and 0.90-J energy levels had the potential to effectively treat the ciliary epithelium.