Assessment of the iCare HOME2, a New IOP Self-Measurement Tonometer.

Abstract

The iCare HOME2 tonometer generally can be considered reliable for most eyes and clinical settings, although it may produce slightly overestimated or underestimated intraocular pressure readings in thicker and thinner corneas, respectively. To evaluate the accuracy, correlation, and analysis of differences in intraocular pressure (IOP) measurements between the gold standard Goldmann applanation tonometer (GAT) and the new, self-measurement iCare HOME2 tonometer (icare, Vantaa, Finland). In this retrospective study, patients were randomly selected from those who attended for a routine examination in our clinic. After a complete ocular examination, each patient's IOP was measured and recorded with GAT (IOPG) and iCare HOME2 (IOPi). Central corneal thickness (CCT) was measured. Eyes with any corneal morbidity were excluded. Pearson's correlation coefficient was used to determine correlation between paired IOP measurements. Bland-Altman plots were graphed for the analysis of differences for IOP between the instruments. One hundred and thirty-five eyes of 70 patients were included in the study. The mean IOPG was 16.3 ±6.5mm Hg (range 3-56). The mean IOPi was 16.5 ±7.3mm Hg (range 3-55), (P=0.47). A strong, significant positive correlation was found for paired IOP measurements by the two instruments (r=0.94; P<0.0001). A small systematic proportional bias was seen for the paired IOP measurements, meaning that with higher IOPs the iCare HOME2 yielded higher IOP readings than GAT; but this difference was clinically insignificant. The instrument underestimated IOPs with corneas thinner than 522 µm while it overestimated IOPs when corneas were thicker than this. The iCare HOME2 could be a reliable tonometer for most eyes and clinical settings. CCT measurement is recommended in patients who use the instrument.