Histopathologic changes in cadaver eyes after MicroPulse and continuous wave transscleral cyclophotocoagulation

The purpose of this study was to compare the acute histological effects of MicroPulse transscleral cyclophotocoagulation (MPCPC) using the MicroPulse P3 Device and continuous wave transscleral cyclophotocoagulation (CWCPC) on the ciliary body and adjacent structures in human cadaver eyes.

Quadrants of 6 human cadaver eyes from 3 different donors were subjected to traditional CWCPC, slow burn CWCPC, MPCPC, or no treatment (internal control). Sutures were used to differentiate different treatment areas on each eye. Differential inking was applied after treatments to aid in microscopic correlation. All specimens were subject to standard histologic processing. Tissue sections were cut at 4 microns and stained with hematoxylin and eosin according to established protocols. Pathologic evaluation by light microscopy was confirmed by a senior pathologist blinded to treatment groups.

In all 6 eyes, tissues treated with traditional and low burn CWCPC showed variable coagulative tissue damage to the ciliary body compared with untreated tissues. Minimal histologic changes were identified within the ciliary processes, although variable pigment clumping and streaming were noted within the pigmented ciliary epithelium. In contrast to CWCPC, MPCPC-treated tissues showed only minimal coagulative tissue damage to the ciliary body. Variable pigment clumping and streaming, however, were also noted in the pigmented ciliary epithelium in MPCPC-treated tissues.

In human cadaver eyes, MPCPC treatment caused less tissue disruption to the ciliary body compared with traditional and low burn CWCPC treatments. MPCPC may be a less destructive and more selective method of cyclophotocoagulation when compared with traditional and low burn CWCPC.