IOP agreement between I-Care TA01 rebound tonometer and the Goldmann applanation tonometer in eyes with and without glaucoma

To analyze correlation of intraocular pressure (IOP) measurement between new rebound tonometer (RBT) I-Care TA01 and Goldmann applanation tonometer (GAT). One hundred eighty-five eyes of 185 subjects presenting with glaucoma or cataract were enrolled in the study. In all patients, IOP was obtained by an ophthalmologist using I-Care TA01 and GAT. IOP between the two were compared at range of 8–15, 16–21, and >22 mmHg and difference was considered as significant at p < 0.05 (t test). Bland–Altman analysis tested agreement between instruments overall and for each subgroup of patients with glaucoma or no glaucoma (cataract only). Of 185 patients, 86 had glaucoma; 99 did not. Mean age of patients was 55.77 ± 14.46 years; with no difference between the two subgroups (p = 0.12). There was no significant difference in mean IOP between the two tonometers at IOP between 8–15 mmHg (p = 0.097) and 16–21 mmHg (p = 0.51). However, a significant difference was observed between the two at IOP > 22 mmHg (p = 0.023) with mean GAT (24.8 mmHg) being higher than mean RBT (23.16 mmHg). Overall, there was no difference between the two (p = 0.59) and they had a high correlation (Pearson correlation r = 0.815; p = 0.01). The mean difference between the two was 0.1 (95 % agreement limits: UL +6 (1.96SD), LL −5.8 (−1.96SD)), in patients with no glaucoma was 0.091 (95 % AL: UL +4.8 (1.96SD), LL −4.6 (−1.96SD)), and in patients with glaucoma was 0.151 (95 % AL: UL +7.25 (1.96SD), LL −6.9 (−1.96SD)). RBT I-Care TA01 and Goldmann tonometer cannot be used interchangeably due to large limits of agreement.