Short-Term Stability of Retinal Nerve Fiber Layer and Ganglion Cell Layer Thickness Following Direct Selective Laser Trabeculoplasty in Patients with Ocular Hypertension and Glaucoma

Background/Objectives: To evaluate the short-term effects of direct selective laser trabeculoplasty (DSLT) on retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thickness in patients with ocular hypertension (OHT) and primary open-angle glaucoma (POAG). Methods: This retrospective, single-center study included 45 eyes of 45 patients with OHT or POAG who underwent DSLT at Shaare Zedek Medical Center between February 2024 and February 2025. The primary outcome was the change in RNFL and GCL thickness, as measured by spectral-domain optical coherence tomography (SD-OCT) before and two months after treatment. Secondary outcomes included intraocular pressure (IOP) reduction, corrected distance visual acuity (CDVA), and safety. Only high-quality OCT scans (quality score > 25) were included in the analysis. Results: OCT analysis revealed no statistically significant changes in the inner retinal structure two months post-treatment. The mean RNFL thickness was 77.1 ± 17.2 µm at baseline and 77.4 ± 17.3 µm at follow-up (p = 0.285). The mean GCL thickness remained unchanged (42.4 ± 11.6 µm vs. 42.4 ± 11.3 µm, p = 0.750). CDVA remained stable (0.2 ± 0.4 vs. 0.2 ± 0.4 logMAR; p = 0.351), and no vision-threatening complications were observed. Mean IOP decreased significantly from 19.7 ± 4.0 mmHg at baseline to 16.2 ± 3.5 mmHg at two months (p < 0.001). The mean total laser energy delivered was 196.5 ± 10.2 mJ (range: 176–210 mJ). Conclusions: DSLT was not associated with significant short-term changes in RNFL or GCL thickness, supporting its structural safety in patients with OHT or glaucoma. Further long-term studies are warranted to determine the durability of these findings and the potential neuroprotective effects of DSLT.