Retinal nerve fiber layer changes following cataract surgery in patients with and without preperimetric glaucoma

Background: Preperimetric glaucoma (PPG) is characterized by structural optic nerve damage without detectable functional impairment. Optical coherence tomography (OCT) is increasingly utilized to monitor glaucoma, though its reliability can be compromised by lens opacities. This study investigates retinal nerve fiber layer (RNFL) thickness changes after cataract surgery in patients with and without PPG, aiming to assess potential diagnostic inaccuracies due to cataract-induced imaging artifacts. Methods: Thirty eyes from 30 patients undergoing cataract surgery were analyzed, divided into two groups: Group 1 (n = 15) without glaucoma and Group 2 (n = 15) with PPG diagnosed using the Global Glaucoma Staging System. RNFL thickness was measured using Spectral-Domain OCT before and one month after phacoemulsification. Statistical analysis was performed using SPSS v23.0. Results: Postoperative RNFL thickness increased significantly in both groups, with a greater mean change in the PPG group (mean increase: 13 µm vs. 7 µm in controls; p < 0.00001). The greatest changes were observed in the inferior quadrants (p < 0.001). Image quality improved by approximately 34% post-surgery (p < 0.001). Despite higher postoperative RNFL values, none of the PPG eyes were reclassified as normal. Conclusions: In eyes with mild nuclear cataract, lens-related signal attenuation reduces absolute RNFL values but, in this cohort, had negligible impact on structural diagnostic classification. OCT-based structural findings in early glaucoma should therefore be interpreted with caution in the presence of cataract—recognizing that measurement bias may alter thickness values without changing PPG classification. Cataract surgery improves OCT reliability and can refine subsequent glaucoma assessment.