The effects of silicone oil removal. Silicone Study Report 6

Abstract

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 Silicone Study, a randomized, multicentered, surgical trial.

Setting: Community- and university-based clinics.

Patients: Two hundred twenty-two eyes with severe proliferative vitreoretinopathy followed up in the Silicone Study.

Interventions: Vitrectomy for proliferative vitreoretinopathy with silicone oil as the intraocular tamponade.

Outcome measures: Changes in visual acuity, recurrent retinal detachment, and incidence of complications.

Results: Ninety-nine (45%) of 222 eyes had surgery for silicone oil removal (oil-removed eyes). Compared with the eyes that did not undergo silicone oil removal (oil-retained eyes) evaluated at a comparable time after oil injection, oil-removed eyes at the examination 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 association between the length of oil retention and incidence of recurrent retinal detachment after oil removal. Eyes with attached retinas at the time of oil removal generally improved in visual acuity at the last follow-up examination (P < .0001), which was not evident in eyes with detached retinas at the time of oil removal. In a matched-pair cohort analysis comparing both sets of eyes, there was an increased risk for recurrent retinal detachment at the last follow-up examination in the oil-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 oil-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 silicone oil in anatomically successful eyes significantly increases the likelihood of improved visual acuity with a slight increase in the likelihood of recurrent retinal redetachment. There was a trend for a reduction in the incidence of complications in the oil-removed eyes.