Abstract
Purpose :
The ability of patients to measure their own intraocular pressure (IOP) would allow more frequent measurements and offer the potential for remote disease monitoring and improved patient engagement. The aim of this study was to examine if patients can perform self-tonometry using a rebound tonometer and examine the effect of corneal biomechanics.
Methods :
100 subjects had a comprehensive examination followed by training in self-tonometry using a rebound tonometer (Icare HOME, Finland)(www.clinicaltrials.gov NCT03057301). Participants were instructed to measure their own IOP, with complete success defined by good technique and obtaining an IOP within 5mmHg of that recorded by a clinician using the same device. IOP was also measured using Goldman applanation tonometry (GAT) and the Ocular Response Analyzer (ORA). Corneal hysteresis (CH), corneal resistance factor (CRF) and central corneal thickness (CCT) were also measured. Intraclass correlation coefficients were used to assess reproducibility, Bland-Altman plots to examine agreement, and regression analyses to evaluate the relationship between IOP, CCT, CRF and CH.
Results :
Subjects had a mean age of 67.5 ± 10.9 years. Average mean deviation was -2.25 +/- 6.04 dB in the better eye. 73% could successfully perform tonometry. Average self-tonometry IOP measurements were 14.3 +/- 3.9 mmHg, an average of 2.7 mmHg lower than GAT (95% limits of agreement 3.5 to 8.8 mmHg). Self-tonometer measurements had excellent reproducibility with an ICC of 0.90 (95% CI 0.87 to 0.93). Average CCT, CRF and CH were 534.45 ± 37.36μm, 8.99 ± 1.71mmHg, and 9.44 ± 1.52 mmHg respectively. GAT and Icare HOME measurements were significantly lower in eyes with thinner CCT and lower CH, however self-tonometry measures had a stronger association with CCT than GAT, while GAT had a stronger association with CH. CH remained associated with IOP measurements after accounting for CCT.
Conclusions :
Self-tonometry is a feasible method of IOP monitoring, allowing multiple measurements to be obtained. Most subjects could perform self-tonometry and the method was acceptable to patients. There was good agreement with GAT however measurements were influenced by CCT and CH.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.