Test-Retest Reliability of Intraocular Pressure Measurements With Office-Based Versus Home-Based Rebound Tonometers.

Prcis: Intraocular pressure (IOP) measurements obtained with the HOME2 rebound tonometer are interchangeable with measurements obtained using the office-based IC100 and IC200 rebound tonometers, making characterization of circadian IOP achievable with no inter-device sources of variability.

Objective: To evaluate test-retest reliability between IOP measurements obtained with a home rebound tonometer operated by patients and those obtained with office rebound tonometers operated by experienced clinical staff.

Methods: After training and practice with a home rebound tonometer (iCare HOME2) in a randomly selected eye, patients with established or suspected open angle glaucoma underwent IOP measurement in the fellow eye as follows in randomized order: 3 good quality measurements with the iCare IC100 operated by experienced clinical staff, 3 good quality measurements with the iCare IC200 operated by experienced clinical staff, and 3 good quality measurements with the HOME2 operated by the patient. The Shrout-Fleisch intraclass correlation coefficient (ICC; 2,1) was the measure of reliability utilized based on the model using 2-way random effects, absolute agreement, and single measurement.

Results: Thirty eyes of 30 patients were evaluated. The Pearson correlation coefficient ( r ) for IOP measurements taken with the IC100 and HOME2 was 0.97, with the IC200 and HOME2 was 0.96, and with the IC100 and IC200 was 0.97. Test-retest reliability between HOME2 and IC100 (ICC: 0.90), HOME2 and IC200 (ICC: 0.92), and IC100 and IC200 (ICC: 0.94) all reflected excellent test-retest reliability.

Conclusion: The test-retest reliability of IOP measurements taken by patients using the iCare HOME2 self-tonometer compared with IOP measurements taken by trained operators using the iCare IC100 and IC200 tonometers was uniformly excellent (ICCs all ≥0.9). These findings indicate that these three devices should be considered interchangeable for the clinical assessment of circadian IOP.