Pars plana vitrectomy for tractional and combined tractional rhegmatogenous retinal detachment in type 1 diabetes mellitus: outcomes, prognostic factors, and a proposed staging system.

Abstract

Background: Pars plana vitrectomy (PPV) in young type 1 diabetes mellitus (T1DM) patients presents greater surgical challenges than in type 2 (T2DM) cases. Despite advances in vitreoretinal surgery, there is no universally accepted classification system for tractional retinal detachment (TRD), and limited data exist on the comparative effectiveness of endotamponade agents and the prognostic significance of outer retinal biomarkers in T1DM cohorts. This study evaluates PPV outcomes for TRD and combined tractional rhegmatogenous retinal detachment (TRRD) in T1DM, introduces a proposed staging system for TRD, assesses the impact of tamponade selection on outcomes, and investigates the role of outer retinal structural biomarkers in predicting visual success.

Methods: A retrospective cohort study was conducted at King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia, on T1DM patients treated with PPV for TRD and combined TRRD between June 2014 and December 2022. A novel TRD staging system was proposed based on the extent of the tractional membrane, posterior hyaloid attachment status, and the presence of retinal breaks, classifying cases into simple TRD (stages 1, 2, 3a), complex TRD (stages 3b, 4, 5), and combined TRRD (acute and chronic). Anatomical success was defined as retinal reattachment, and visual success was defined as improvement in visual acuity of more than two Snellen lines. Postoperative optical coherence tomography (OCT) at 1 year assessed external limiting membrane (ELM) and ellipsoid zone (EZ) integrity.

Results: Among 339 eyes (255 patients), complex TRD was the most common presentation (41.6%). Iatrogenic retinal breaks occurred in 39.2%, and tamponade was used in 74.0% of cases. Anatomical success was achieved in 73.2% after a single surgery and 91.2% overall. Visual success was achieved in 55.2% of eyes, with vision improvement observed in 69.2%. Eyes without tamponade achieved the highest visual success rate (80.8%), followed by gas tamponade (84.3% for C3F8/SF6) compared to silicone oil (51.9%) (p < 0.001). Combined TRRD had significantly lower visual success compared to complex TRD (47.3% vs. 64.5%, p = 0.018). Multivariate analysis identified preoperative LogMAR visual acuity (RR 9.88, 95% CI: 4.68-20.83, p < 0.001), intact ellipsoid zone status (RR 20.4, 95% CI: 3.8-109.41, p < 0.001), combined TRRD stage (RR 0.08, 95% CI: 0.01-0.5, p = 0.007), and absence of subretinal fluid (RR 3.49, 95% CI: 1.12-10.87, p = 0.031) as significant independent predictors of visual success.

Conclusion: PPV for TRD in T1DM achieves excellent overall anatomical outcomes. The proposed TRD staging system demonstrated prognostic value, with combined TRRD carrying a worse visual prognosis. Preoperative visual acuity, TRD stage, outer retinal integrity (ELM/EZ) on postoperative OCT, and tamponade type were significant determinants of functional outcomes. The association of silicone oil tamponade with poorer visual outcomes likely reflects indication bias, as silicone oil was preferentially used in more complex cases. The proposed staging system is hypothesis-generating and requires prospective multicenter validation.