EFFECTS OF SILICONE OIL REMOVAL - SILICONE STUDY REPORT-6

Objective: To evaluate the advisability of removing silicone oil from eyes after surgery for severe (with a classification of at least C-3) proliferative vitreoretinopathy. Design: Subgroup analysis of the Sili cone Study, a randomized, multicentered, surgical trial. Setting: Comm unity- and university-based clinics. Patients: Two hundred twenty-two eyes with severe proliferative vitreoretinopathy followed up in the Si licone Study. Interventions: Vitrectomy for proliferative vitreoretino pathy with silicone oil as the intraocular tamponade. Outcome Measures : Changes in visual acuity, recurrent retinal detachment, and incidenc e of complications. Results: Ninety-nine (45%) of 222 eyes had surgery for silicone oil removal (oil-removed eyes). Compared with the eyes t hat did not undergo silicone oil removal (oil-retained eyes) evaluated at a comparable time after oil injection, oil-removed eyes at the exa mination prior to oil removal were more likely to be attached (85% vs 40%; P<.0001), have a visual acuity of 5/200 or greater (63% vs 35%; P <.0001), and not be hypotonous (5% vs 22%; P<.001). There was no assoc iation between the length of oil retention and incidence of recurrent retinal detachment after oil removal. Eyes with attached retinas at th e time of oil removal generally improved in visual acuity at the last follow-up examination (P<.0001), which was not evident in eyes with de tached retinas at the time of oil removal. In a matched-pair cohort an alysis comparing both sets of eyes, there was an increased risk for re current retinal detachment at the last follow-up examination in the oi l-removed eyes (odds ratio [OR], 2.1; P=.09). However, overall visual acuity improved for oil-removed eyes in 19 (29%) of 66 pairs and for o il-retained eyes in one (2%) of 66 pairs (OR, 19.0; P<.0001). Although nonsignificant, incidence rates of keratopathy (OR, 0.5) and hypotony (OR, 0.5) were lower in oil-removed eyes. Conclusion: Removal of sili cone oil in anatomically successful eyes significantly increases the l ikelihood of improved visual acuity with a slight increase in the like lihood of recurrent retinal redetachment. There was a trend for a redu ction in the incidence of complications in the oil-removed eyes.