EVALUATION OF THE TONO-PEN-2 AND THE X-PERT(TM) NONCONTACT TONOMETERSIN CATARACT-SURGERY

The Oculab Tone-Pen and the X-Pert (TM) noncontact tonometers (NCTs) w ere compared to the Goldmann applanation tonometer in a consecutive se ries of 45 patients before and after cataract surgery. In the preopera tive period, the mean value of the paired difference at intraocular pr essure (IOP) measurements was -1.30+/-2.11 mm Hg (mean+/-SD) for the X -Pert NCT (X-Pert NCT minus Goldmann) and -0.19+/-2.56 mm Hg for the T one-Pen 2 (Tone-Pen 2 minus Goldmann). In the postoperative period, th is mean difference was 0.26+/-2.45 mm Hg for the X-Pert NCT and 0.87+/ -2.83 mm Hg for the Tone-Pen 2. We found 87 and 67% of the X-Pert NCT and the Tone-Pen 2 readings to be within +/-2 mm Hg of the Goldmann Ke y Words readings, respectively. In both preoperative and postoperative Applanation eyes, correlation coefficients between the readings of th e three instruments were high (ranging from 0.84 to 0.96). Differences between the three tonometers were not correlated with corneal thickne ss of corneal curvature postoperatively. Both Tono-Pen 2 and X-Pert NC T could thus be considered accurate instruments for IOP screening afte r cataract surgery when compared to the Goldmann applanation tonometer .