Incidence of and Risk Factors for Silicone Oil-Associated Cystoid Macular Edema After Pars Plana Vitrectomy

Purpose: To observe the incidence of and risk factors for cystoid macular edema (CME) after silicone oil (SO) implantation after pars plana vitrectomy (PPV) for retinal detachment (RD) repair. Methods: This retrospective analysis used the TriNetX database to identify patients who received SO tamponade after PPV for RD between March 2014 and March 2023. The onset and regression of CME were identified using spectral-domain optical coherence tomography. The demographics, intraoperative parameters, and postoperative disease course of patients with and patients without CME were compared using χ² tests, Student t tests, and logistic regression models. Results: Twenty (25.3%) of 79 eyes developed CME after intraocular insertion of SO. The use of 1000 cs SO (n = 50) vs 5000 cs SO (n = 29) was significantly associated with CME onset (odds ratio, 4.46; P < .05). The mean (± SD) SO tamponade duration was 199.0 ± 125.5 days. The mean time from SO implantation to detection of CME was 82.6 ± 57.9 days. Disease regression occurred in 15 (75.0%) of the 20 eyes with CME and was recorded a mean of 218.2 ± 256.2 days after SO removal. Compared with untreated groups, the frequency of CME regression was not influenced by the administration of sub-Tenon triamcinolone acetonide (75.0% vs 75.0%; P = 1.00), prednisolone acetate eyedrops (75.0% vs 75.0%; P = 1.00), or ketorolac eyedrops (71.4% vs 76.9%; P = .79). Conclusions: The viscosity of the SO used for vitreous tamponade in RD repair may play a role in the development of CME, with lighter grade oil increasing the risk for disease. Furthermore, SO removal alone potentially leads to a prominent reduction in CME in most cases.