Visual loss after use of intraocular silicone oil associated with thinning of inner retinal layers

. Purpose: To investigate the incidence and cause of severe visual loss following use and removal of intraocular silicone oil (SiO) after uncomplicated vitrectomy and SiO injection for primary rhegmatogenous retinal detachment (RRD). Methods: Consecutive case series of 216 patients operated with vitrectomy for primary RRD in 20042005. In 162 eyes, SiO (5500 centiStoke) had been used as intravitreal tamponade and in 54 eyes gas (perflouropropane, C3F8) had been used. Following chart review, we identified 16 eyes in 16 patients (nine SiO eyes, seven gas eyes) with macula-on and documented visual acuity =6/12 before surgery, where SiO had been removed, cataract surgery performed and no re-detachment had occurred. Examinations included best-corrected visual acuity (BCVA) and high-definition optical coherence tomography (OCT) of the macular area. Results: Preoperative characteristics were identical between SiO and gas eyes. Postoperative BCVA was significantly worse in SiO eyes (>6/24) compared to gas eyes (>6/7.5), p = 0.005. Three of 9 (33%) SiO eyes had final BCVA =6/60 and 67% had final BCVA =6/12. No gas eyes had final BCVA <6/9. Macular OCT revealed thinning of inner retinal layers in SiO-operated eyes (5148 pixels) compared to gas-operated eyes (6897 pixels), p < 0.002. No other visually significant structural differences were found. Conclusion: Severe visual loss after SiO use was observed in 1/3 of patients with otherwise good visual potential. The visual loss was associated with a significant reduction in inner retinal thickness indicating neuronal cell loss in the macular area as a possible explanation.