Reproducibility of 5 Methods of Ocular Tonometry

PURPOSE:To evaluate the agreement between Goldmann applanation tonometry (GAT; Haag-Streit, Bern, Switzerland) and several portable tonometers that could be used for glaucoma screening programs. DESIGN:Evaluation of a diagnostic test. PARTICIPANTS:Three hundred twenty-one eyes of 168 participants seeking treatment at the glaucoma clinic of a tertiary eye hospital in India. METHODS:Participants underwent intraocular pressure (IOP) measurement with GAT and 4 index tests: the Icare TA01i rebound tonometer (Icare USA, Raleigh, NC), a noncontact tonometer (NCT; Topcon CT-80; Topcon; Tokyo, Japan), a pneumatonometer (Model 30; Reichert Technologies; Depew, NY), and the Tono-Pen AVIA (Reichert Technologies). MAIN OUTCOME MEASURES:Estimates of reproducibility of IOP measurements between each index test and GAT, including the intraclass correlation coefficient (ICC) and the Bland-Altman 95% limits of agreement. RESULTS:The Icare showed the greatest agreement with GAT (ICC, 0.69; 95% confidence interval, 0.61-0.74), followed by the NCT (ICC, 0.65; 95% confidence interval, 0.58-0.71), the Tono-Pen (ICC, 0.51; 95% confidence interval, 0.43-0.59), and the pneumatonometer (ICC, 0.36; 95% confidence interval, 0.27-0.44). The pneumatonometer and Tono-Pen tended to overestimate IOP relative to GAT, with a mean difference of 3.4 mmHg (95% limits of agreement [LOA], -7.3 to 14.1 mmHg) for the pneumatonometer and 3.2 mmHg (95% LOA, -6.1 to 12.6 mmHg) for the Tono-Pen. In contrast, measurements from the Icare and NCT were on average within 1 point of those for GAT (mean difference, -0.4 mmHg [95% LOA, -8.4 to 7.6 mmHg] and -0.5 mmHg [95% LOA, -8.7 to 7.6 mmHg], respectively). CONCLUSIONS:The Icare and NCT both demonstrated good agreement with GAT across a wide range of IOPs and could be considered for glaucoma screening programs.