Endoscopic Cyclophotocoagulation and Other Cyclodestructive Methods: Histopathologic Comparison of In Vivo Treatment in Humans and Monkeys.

Purpose: To compare the histologic effects of endoscopic cyclophotocoagulation (ECP) with other ciliary body ablative procedures. A secondary aim was to correlate these findings with historical clinical success and complication rates.

Design: Prospective, qualitative comparison of histopathologic tissue analysis.

Participants: Two eyes of two patients who had undergone ECP for open-angle glaucoma were studied. Two eyes from a healthy monkey were treated with ECP and studied. For comparison, 1 eye each of patients who had undergone contact and noncontact neodymium:yttrium-aluminum-garnet transscleral cyclophotocoagulation (TCP) for open-angle glaucoma were analyzed.

Methods: The human globes were enucleated and submitted for analysis by gross examination and light and electron microscopy. Monkey eyes were studied by gross examination and light microscopy 1 week, 2 weeks, and 1 month after ECP.

Main Outcome Measures: Gross and histopathologic specimens of all eyes were analyzed with respect to location and type of tissue effects and degree of collateral damage.

Results: The gross analysis of all ECP specimens showed a uniform anterior-to-posterior whitening of each treated ciliary process. This correlated with microscopic evidence of loss of pigmentation from the pigmented ciliary epithelial cells seen with mostly preserved architecture and vasculature of the ciliary processes. By comparison, the TCP specimens showed erratic treatment of the ciliary processes with overlap into the pars plicata of the ciliary body. Microscopic analysis revealed significant disruption of the cells throughout the ciliary processes and loss of vessels within the stroma.

Conclusions: Treatment with ECP results in less overall tissue destruction and a targeted effect on the pigmented ciliary epithelium of the ciliary processes when compared with TCP.