Elevated intraocular pressure and hypotony following silicone oil retinal tamponade for complex retinal detachment - Incidence and risk factors

Objective: To evaluate the incidence of and risk factors for persistently e levated intraocular pressure (IOP) and hypotony in patients who have underg one pars plana vitrectomy with silicone oil injection for the management of complex retinal detachment. Subjects and Methods: The medical records of 532 patients who underwent sil icone oil injection for the management of complex retinal detachments betwe en January 1, 1991, and December 31, 1996, at the Bascom Palmer Eye Institu te, Miami, Fla, were reviewed. Elevated IOP was defined as elevated IOP req uiring an operation at any time postoperatively or a persistently elevated IOP of greater than 25 mm Kg at or after the 6-month visit. Hypotony was de fined as a persistent IOP of 5 mm Kg or less at or after the 6-month visit. Patients with transient perioperative IOP fluctuations were not counted. Results: Survival analysis for patients without cytomegalovirus retinitis ( n = 383) revealed that 12.9% had an elevated IOP and 14.1% had hypotony by 6 months, 21% had an elevated IOP and 20.3% had hypotony by I year, and 29. 5% had an elevated IOP and 27.3% had hypotony by 2 years. Among patients wi th cytomegalovirus retinitis (n = 149), none had a persistently elevated IO P, 10% had hypotony by 6 months, and 5.9% had persistently elevated IOP and 10% developed chronic hypotony by 1 year. A history of glaucoma before sil icone oil retinal tamponade (P = .03), diabetes mellitus (P = .02), and a h igh IOP on the first postoperative day (P = .006) were risk factors for ele vated postoperative IOP in patients without cytomegalovirus retinitis. Risk factors for postoperative hypotony in patients without cytomegalovirus ret initis included preoperative hypotony (P<.001) and aphakia (P=.03). Conclusions: An elevated or low IOP often develops postoperatively in patie nts without cytomegalovirus retinitis who undergo silicone oil injection fo r the management of complex retinal detachment. Risk factors for an elevate d postoperative IOP include a history of glaucoma, diabetes mellitus, and a high IOP on the first postoperative day. Risk factors for hypotony include preoperative hypotony and aphakia.