Supine and Sitting Intraocular Pressure Measurements Using iCare HOME2 Self-Tonometry and iCare IC200 Rebound Tonometry in Japanese Open-Angle Glaucoma Patients

Purpose: To evaluate supine and sitting intraocular pressure (IOP) self-measurements using iCare-HOME2 self-tonometry (iCare-HOME2) and to compare the results with corresponding iCare IC200 IOP (iCare) measurements by health care professionals on Japanese glaucoma patients. Methods: Thirty-six eyes of 36 consecutive primary open-angle and normal-tension glaucoma patients were examined. IOP was measured in sitting position using Goldmann applanation tonometry (GAT), iCare, and iCare-HOME2 self-tonometry, then after a 10-minute supine rest with iCare tonometry and iCare-HOME2 self-tonometry in supine position. ANOVA, intraclass correlation coefficients (ICC) and Bland–Altman analyses were used. Results: Mean IOPs were 15.8 mmHg (GAT), 13.6 mmHg (iCare), and 14.6 mmHg (iCare-HOME2) in sitting (P ≤ 0.049), and 16.8 mmHg (iCare) and 16.8 mmHg (iCare-HOME2) in supine position (P = 0.99). ICCs between iCare-HOME2 and iCare were 0.899 (95% CI, 0.712– 0.957) in sitting and 0.976 (95% CI, 0.954– 0.988) in supine position. Bland–Altman analysis showed minimal bias in both positions (mean differences: 1.03 mmHg [limits of agreement: − 2.07 to 4.14] in sitting; and − 0.003 mmHg [− 2.18 to 2.17] in supine position). Conclusion: iCare-HOME2 self-tonometry can accurately measure IOP in both sitting and supine positions. Based on the ICC values, the agreement between IOP values measured by health-care professionals with iCare and by trained open-angle glaucoma patients with iCare HOME2 was higher in the supine position than in the sitting position. Our results suggest that self-measured sitting and supine iCare-HOME2 IOP data are reliable on trained glaucoma patients and may potentially be applied to assist clinical decision making in glaucoma care.