Evaluation of Changes in the Iridocorneal Angle and Anterior Segment Parameters Following Selective Laser Trabeculoplasty in Pseudoexfoliation Glaucoma

Objectives: To investigate the effects of selective laser trabeculoplasty (SLT) on the iridocorneal angle, anterior chamber, and iris in patients with pseudoexfoliation glaucoma (PEXG) and to evaluate the relationship between these structural changes and intraocular pressure (IOP) reduction. Materials and Methods: Thirty-two eyes of 32 PEXG patients were included in the study. Anterior segment optical coherence tomography (AS-OCT) images were obtained using the MS-39 combined Placido disk/AS-OCT system (Phoenix version 4.1.1.5) before SLT and at 1 week and 1 month after SLT. Anterior chamber angle (ACA), angle opening distance at 250 μm, 500 μm, and 750 μm (AOD250, AOD500, and AOD750), and trabecular-iris space area at 250 μm, 500 μm, and 750 μm (TISA250, TISA500, and TISA750) were measured from these images. In addition, iris thickness was assessed at 1000 μm, 2000 μm, and 3000 μm from the pupillary margin. Results: The mean IOP decreased significantly from 23.47±3.56 mmHg at baseline to 17.81±2.62 mmHg at 1 week and 16.12±2.57 mmHg at 1 month after SLT (p<0.001). At both 1 week and 1 month after SLT, temporal and nasal ACA values were significantly greater compared to baseline (all p<0.05). At 1 month, significant increases were observed in all temporal AOD and TISA values, as well as in the nasal AOD, TISA500, and TISA750 values (all p<0.05). No significant change in iris thickness was observed (p>0.05). Changes in IOP showed no significant correlation with baseline visual field parameters, baseline peripapillary retinal nerve fiber layer thickness, ACA, AOD, or TISA values (all p>0.05). Conclusion: In patients with PEXG, SLT effectively reduces IOP and leads to widening of iridocorneal angle parameters. However, the absence of a correlation between changes in angle parameters and IOP reduction strengthens the notion that the primary effect of SLT is related to cellular and biochemical mechanisms rather than a purely mechanical widening of the angle.