Investigation of corneal endothelial changes post selective laser trabeculoplasty

Importance: Transient corneal endothelial changes are routinely noted on slit-lamp examination immediately following selective laser trabeculoplasty (SLT).

Background: To determine the mechanism of transient corneal endothelial changes observed following SLT.

Design: University laboratory-based observational study.

Samples: Ten corneas from six human cadaveric donors.

Methods: Corneas were treated with SLT, direct laser or peroxide, or used as controls. Haematoxylin and eosin staining and immunolabelling for zonula occludens-1 (ZO-1) and beta-catenin were performed.

Main outcome measures: Histological appearance; ZO-1 and beta-catenin immunostaining.

Results: There were no differences in histological features between SLT-treated and control corneas. Corneas treated with SLT or peroxide showed reduced and less regular ZO-1 immunofluorescence along cell membranes compared with ZO-1 expression in controls. These changes were generalized across the endothelium. There was no effect on the ZO-1 immunostaining after direct laser. There was no difference in beta-catenin immunostaining patterns between control, SLT and peroxide-treated corneas.

Conclusions and relevance: Altered ZO-1 immunostaining may represent disassembly of tight junctions between corneal endothelial cells. The similarity of our findings between SLT-treated and peroxide-treated corneas suggests that both conditions trigger changes at the level of endothelial tight junctions, perhaps triggered by liberation of free radicals as previously proposed.