Comparative evaluation of TonoPen AVIA, Goldmann applanation tonometry and non-contact tonometry

To compare the tonometric recordings of the Tono-Pen AVIA (TPA) with intraocular pressure (IOP) recordings made with Goldmann applanation tonometry (GAT) and non-contact tonometry (NCT). This prospective, observational, comparative case series consisted of 180 eyes of 180 subjects (50 patients with glaucoma and 130 healthy controls). NCT was performed first, followed by GAT and TPA measurement after a 5-min break. The mean age of the patients enrolled in the study was 43.99±16.67 years. The limits of agreement (confidence interval 95%) as calculated from the Bland-Altman plots for TPA-GAT and TPA-NCT were +8.7 to -7.7 and +8.6 to -9.6 mmHg in glaucoma patients. In healthy subjects these values were +4.8 to -5.1 and +6.2 to -5.2 mmHg, respectively. TPA tends to overestimate IOP compared to GAT at central corneal thickness (CCT) greater than 520 μm and underestimate IOP at CCT less than 510 μm. TPA overestimates IOP in comparison to NCT in subjects with CCT greater than 456 μm. Due to wide limits of agreement, TPA cannot be used interchangeably with GAT and NCT in the serial monitoring of glaucoma patients. Central corneal thickness has a significant influence on the IOP readings measured by Tono-Pen AVIA.