Publisher: Hospital Clínico San Carlos, Madrid, Spain, July 2020

Authors: P Perez-Garcia, L Morales-Fernandez, F Saenz-Frances , C D Mendez-Hernandez, J Garcia-Feijoo, E Santos-Bueso , J M Martinez-de-la-Casa

Comparison of intraocular pressure measured using the new icare 200™ rebound tonometer and the Perkins™ applanation tonometer in healthy subjects and in patients with primary congenital glaucoma


Objective: To compare intraocular pressure (IOP) measurements obtained using the Icare 200™ (IC200) rebound tonometer and the hand-held version of the Goldmann Applanation Tonometer (Perkins™ tonometer, GAT) in patients with primary congenital glaucoma (PCG) and in healthy subjects.

Material and methods: A total of 42 eyes of healthy subjects (G1) and 40 patients with PCG (G2) were analysed. The following clinical data were collected: gender, age, Cup/Disc ratio, central corneal thickness (CCT). IOP was determined in the examination room using the IC200 and GAT tonometers, in the same order.

Agreement between both tonometers was determined using the intraclass correlation coefficient (ICC) and Bland-Altman plot. A linear regression analysis was used to establish the IOP was affected by the studied variables.

Results: Mean IOP between both tonometers (IC200 minus GAT) was: G1 = 15.91 (2.57) mm Hg vs. 15.06 (2.12) mm Hg (mean difference, MD = 0.84 (0.50) mm Hg; P < .101) and G2 = 20.10 (6.37) vs.19.12 (5.62) (MD = 0.98 (1.36); P = .474).

Excellent agreement was found between IC200 and GAT in both groups (ICC = G1: 0.875 (95% CI; 0.768-0.933; P < .001); G2: 0.924 (95% CI; 0.852-0.961; P < .001), and there was a statistically significant correlation between the IOP difference measured with IC200 and GAT and CCT in G1 (B = 0.021; 95% CI; 0.005–0.037; P = .008), but was not statistically significant in G2.

Conclusion: There was excellent agreement between the IC200 and GAT tonometers, both in healthy subjects and PCG, with a trend to overestimate IOP when measured with IC200. There was no influence by CCT on IOP measurements in patients with PGC.