• The accuracy and precision of tonometric methods in measuring intraocular pressure (IOP) was assessed in 24 eyebank eyes subjected to pars plana lensectomy/vitrectomy and air-fluid exchange. Intraocular pressure was measured in masked fashion with a Perkins' applanation tonometer, pneumatic applanation tonometer, and Schiotz' indentation tonometer; a mercury manometer served as a reference standard. Pneumatic tonometry underestimated actual IOP by as much as 25%, and Schiotz' indentation tonometry underestimated actual IOP by as much as 79%. Perkins' applanation tonometry was significantly more accurate in estimating actual IOP in gas-filled eyes than pneumatic tonometry or Schiotz' indentation tonometry.
Poliner LS, Schoch LH. Intraocular Pressure Assessment in Gas-Filled Eyes Following Vitrectomy. Arch Ophthalmol. 1987;105(2):200-202. doi:10.1001/archopht.1987.01060020054027