Comparison of intraocular pressure measurements with the portable PT100 noncontact tonometer and goldmann applanation tonometry

PURPOSE Noncontact tonometers are useful when regulations preclude use of contact tonometers by medical students and other nonophthalmologists. Our study compared the measurements by the portable, noncontact tonometer (PT100) with Goldmann applanation tonometry (GAT). METHODS This was a prospective study of 98 eyes from 98 patients. Intraocular pressure (IOP) was measured by GAT and the PT100 (Reichert, Buffalo, NY). RESULTS Mean IOP measurements showed no significant differences in measurements performed by the two tonometers (P = 0.64). Measurements by the two tonometers were in agreement by </=3 mmHg in 92.8% of eyes. Linear regression analysis of PT100 vs GAT measurements revealed a slope of 0.98 with r(2) = 0.58. Bland-Altman analysis showed a mean difference of measurements by GAT and PT100 of -0.3 mmHg with two standard deviation = 7.1 mmHg. CONCLUSION The portable noncontact PT100 tonometer provides IOP measurements comparable to GAT within the normal range of IOP.