To determine the incidence and clinical features of chronic elevated intraocular pressure after pars plana vitrectomy and silicone oil injection for complicated retinal detachments, and to evaluate the clinical management of eyes with secondary glaucoma. This was an observational consecutive case series of 450 eyes in 447 patients who were treated with pars plana vitrectomy and silicone oil injection. Patients who developed secondary glaucoma were treated medically with antiglaucoma medications and surgically with glaucoma drainage implants placed in an inferior quadrant. Main outcome measures were intraocular pressure, number of glaucoma medications, surgical success, and complications. Fifty-one of 450 eyes (11%) developed elevated intraocular pressure after pars plana vitrectomy and silicone oil injection whereas 399 eyes (89%) did not have a rise in intraocular pressure. Of the 51 eyes that developed elevated intraocular pressure, 40 (78%) were treated only with glaucoma medicines. Medical therapy reduced the intraocular pressure from a mean +/- SD of 26 +/- 13.4 mm Hg before treatment to 18 +/- 9.1 mm Hg after medical treatment (P = 0.002). The 11 of 51 eyes (22%) with elevated intraocular pressure that failed medical therapy were treated surgically with Ahmed Glaucoma Valve implantation within 12 months of silicone oil injection. In the surgical group, intraocular pressure was reduced from a mean +/- SD of 44 +/- 11.8 mm Hg before surgery to 14 +/- 4.2 mm Hg at the most recent follow-up after surgery (P < 0.001). The number of antiglaucoma medications was reduced from 3.5 +/- 0.7 before surgery to 1.2 +/- 0.5 at the most recent follow-up after surgery (P < 0.001). Chronic intraocular pressure elevation occurs in a minority (11%) of patients who are treated with silicone oil. Most of these eyes are effectively treated with antiglaucoma medications. Eyes that do not respond to medical therapy may be effectively managed with glaucoma drainage implant placement in an inferior quadrant.