Intraocular pressure measurement after pars plana vitrectomy.
The ability of various tonometers to measure intraocular pressure (IOP) accurately after pars plana vitrectomy was determined by using Schiøtz, Goldmann, and Digilab pneumatic tonometers before and after the procedure in 47 eyes. Seventeen of these eyes underwent intraoperative fluid-gas exchange and had an intravitreal gas bubble on the first postoperative day. The Schiøtz tonometer underestimated the Goldmann IOP by more than 10 mmHg in 6 (35%) of 17 eyes after vitrectomy with intravitreal gas and 4 (13%) of 30 eyes without intravitreal gas. The Digilab tonometer did not underestimate the Goldmann IOP by more than 10 mmHg in any eye postoperatively. However, the Digilab tonometer underestimated the Goldmann IOP by more than 5 mmHg in 3 (18%) of 17 eyes after vitrectomy with intravitreal gas and two (7%) of 30 eyes without intravitreal gas.