Intraocular pressure and silicone oil endotamponade

To evaluate intraocular pressure after instillation and eventual removal of silicone oil in patients undergoing pars plana vitrectomy combined with silicone oil endotamponade.

The study included 198 patients who underwent pars plana vitrectomy with silicone oil endotamponade (5,000 centistoke viscosity), in whom silicone oil was removed and in whom follow-up after oil removal was at least 3 months. All patients were operated on by one of two surgeons.

After silicone oil instillation, intraocular pressure increased significantly (P < 0.001) from 12.9 +/- 4.4 mm Hg preoperatively to 16.1 +/- 5.5 mm Hg postoperatively. Intraocular pressure was statistically (P > 0.20) independent of the duration of silicone oil tamponade. Twenty percent of the 198 patients had at least one postoperative intraocular pressure measurement that was higher than 21 mm Hg. Main reasons for increased intraocular pressure were closed inferior iridectomy, iris neovascularisation, silicomacrophagocytic open-angle glaucoma secondary to silicone oil emulsification, and preoperative history of glaucoma. Glaucomatous optic nerve damage was detected in 14 (14 of 198, 7.1%) eyes, including 8 eyes with preoperative 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.

Clinically significant increased intraocular pressure after pars 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 preferred to invasive antiglaucoma surgery to reduce intraocular pressure.