Visual loss after silicone oil removal - Analysis of a German cohort

Introduction: Silicone oil (SO) has been used in ophthalmic surgery for many years as a long-acting endotamponade. However, its use remains a subject of ongoing debate due to potential complications, including emulsification and retinal toxicity. A further concern described by surgeons is the unexplained functional deterioration associated with SO removal. Recent analyses suggest that this SO-associated impairment in visual acuity is an underrecognized problem and may have been insufficiently investigated to date. The present study aims to evaluate visual outcomes after SO 7 removal in eyes that had previously undergone SO tamponade for rhegmatogenous retinal 8 detachment and to identify factors associated with postoperative visual deterioration. Methods: Retrospective single-center longitudinal study at the Department of Ophthalmology, University of Bonn, Germany. Patients who underwent SO (Siluron®; Fluoron, Ulm, Germany) removal in our department within a period of 1.5 years (07/2022 - 12/2023) with a follow-up of at least 6 months were included. Demographic data, clinical course and visual acuity development of these patients were analyzed. In addition, intraocular pressure (IOP), type of silicone oil, optical coherence tomography (OCT) and surgical parameters including duration of the SO tamponade were recorded. The analysis was conducted using a logistic regression model with a binomial link function to estimate the risk of visual loss after SO removal, complemented by predictive modeling and visualization of key predictors' effects on outcome probabilities. Results: A total of 255 SO removals were performed during the review period. The most common reason for SO removal was retinal detachment surgery, accounting for 160 cases (62.7 %). Of these, 88 eyes met the inclusion criteria and were included in the analysis. 63 (72.5 %) were male. The median age at SO removal was 64 years (20-91 years). Macular involvement was present in 38.5 % of retinal detachments. Logistic regression analysis indicated that a greater macular volume of the foveal area >0.23 mm³ during SO endotamponade was significantly associated with a lower risk of visual loss. Further, a higher IOP reduction following surgery was also a significant factor associated with a lower risk of visual deterioration. Conclusion: Visual loss following SO removal remains an underrecognized and insufficiently studied complication. In this cohort, lower foveal macular volume during SO removal and a smaller postoperative decrease in IOP were the only variables signficantly associated with visual deterioration after SO removal.