Aran Kanagaratnam, Keith Ong

Purpose: During selective laser trabeculoplasty, laser energy traverses the corneal endothelium to reach the trabecular meshwork. To investigate cor- neal endothelial changes after SLT, a retrospective cohort study using corneal specular microscopy was performed.
Method: 249 eyes from 136 consecutive patients who had SLT for open angle glaucoma were included. Corneal specular microscopy was per- formed immediately before and after SLT, and at one-month post-SLT. Microscopy data included quantitative measures such as cell density and cen- tral corneal thickness (CCT), and morphological measures including percentage of hexagonal cells and coefficient of variation in cell area (CV).
Results: A small decrease in cell density (2272 452 cells/mm2 vs. 2248 448 cells/mm2, P < 0.01) and increase in CCT (536 39 μm vs 539 41 μm, P < 0.05) were observed between baseline and immediately after SLT. However there was no differ- ence between these parameters at baseline and one month. A small increase in percentage of hexagonal cells was noted between immediately post-SLT and one month post-SLT (49 9 vs. 51 8, P < 0.05). No other changes to percentage of hexagonal cells or CV were found. Neither peak laser energy nor total laser energy were correlated with any of the cell parameter changes. Average total laser energy was lower than in previous studies (41 18 mJ). Conclusion: Small changes were observed immedi- ately post-SLT. The return to baseline at one month may be reflective of transient damage or migration of healthy cells to cover areas of damaged cells.