Changes in Intraocular Pressure and Ganglion Cell Complex Thickness After Pars Plana Vitrectomy in Patients With and Without Diabetes Mellitus

Introduction Pars plana vitrectomy (PPV) is widely performed for various vitreoretinal disorders. However, postoperative elevation of intraocular pressure (IOP) and thinning of the ganglion cell complex (GCC) may adversely affect visual outcomes, particularly in diabetic patients. These changes may be attributed to altered ocular biomechanics, inflammation, and compromised microvascular perfusion in diabetes. Objective The objective of this study was to evaluate postoperative changes in IOP and GCC thickness following PPV and to compare outcomes between diabetic and non-diabetic patients. The study also aims to identify early postoperative trends that may predict long-term neuroretinal damage. Methods This prospective cohort study included 72 patients (36 diabetics and 36 non-diabetics) undergoing PPV for various vitreoretinal indications. IOP and GCC thickness were measured preoperatively and postoperatively on Day 1, Day 7, and at 1 month using Goldmann applanation tonometry and spectral-domain optical coherence tomography (SD-OCT). Patients were followed up at regular intervals, and any postoperative complications were documented. Statistical analysis was performed using SPSS, with p < 0.05 considered statistically significant. Results Baseline demographic and ocular parameters were comparable between the groups. Postoperative IOP was similar on Day 1 but was significantly higher in diabetic patients at Day 7 (p = 0.020) and at 1 month (p = 0.002). IOP spikes were observed only in the diabetic group, suggesting a higher susceptibility to pressure dysregulation. GCC thinning was significantly greater in diabetics at 1 month (p = 0.007), whereas non-diabetic patients showed minimal change. A trend toward progressive GCC reduction was noted in diabetics over time, indicating possible ongoing neurodegenerative changes. Conclusion Diabetes mellitus is associated with sustained postoperative IOP elevation and significant GCC thinning following PPV. These findings highlight the need for closer postoperative monitoring and early intervention in diabetic patients to prevent neuroretinal damage and optimize visual outcomes. Prophylactic IOP control and timely management strategies may play a crucial role in improving surgical outcomes in this high-risk group.