Intraocular pressure and silicone oil endotamponade

Purpose: To evaluate intraocular pressure after instillation and eventual r emoval of silicone oil in patients undergoing pars plans vitrectomy combine d with silicone oil endotamponade. Methods: The study included 198 patients who underwent pars plans vitrectom y with silicone oil endotamponade (5,000 centistoke viscosity), in whom sil icone oil was removed and in whom follow-up after ail removal was at least 3 months. All patients were operated on by one of two surgeons. Results: after silicons oil instillation, intraocular pressure increased si gnificantly (P < 0.001) from 12.9 <plus/minus> 4.4 mm Hg preoperatively to 16.1 +/- 5.5 min Hg postoperatively. Intraocular pressure was statistically (P > 0.20) independent of the duration of silicone oil tamponade. Twenty p ercent of the 198 patients had at least one postoperative intraocular press ure measurement that was higher than 21 mm Hg. Main reasons for increased i ntraocular pressure were closed inferior iridectomy, iris neovascularisatio n, silicomacrophagocytic open-angle glaucoma secondary to silicone oil emul sification, and preoperative history of glaucoma. Glaucomatous optic nerve damage was detected in 14 (14 of 198, 7.1%) eyes, including 8 eyes with pre operative antiglaucoma treatment. Silicone oil emulsification occurring in 40 (40 of 198, 20.2%) patients did not statistically influence intraocular pressure after oil removal. Ocular hypotony occurred in 10 (10 of 198, 5.1% ) patients after oil release leading to intraocular hemorrhages and loss of vision in 3 patients. Conclusion: Clinically significant increased intraocular pressure after par s plana vitrectomy with silicone oil endotamponade occurs relatively rarely , can usually be well controlled by topical antiglaucoma medication, and is reversible in most patients after oil removal. In patients with increased intraocular pressure and silicone oil endotamponade, oil removal may be pre ferred to invasive antiglaucoma surgery to reduce intraocular pressure.