Assessment of the iCare HOME2, a New Intraocular Pressure Self-Measurement Tonometer

Abstract

Précis: 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 (IOP) readings in thicker and thinner corneas, respectively. Purpose: To evaluate the accuracy, correlation, and analysis of differences in IOP measurements between the gold standard Goldmann applanation tonometer (GAT) and the new, self-measurement iCare HOME2 tonometer (icare). Patients and Methods: In this retrospective study, patients were randomly selected from those who attended a routine examination in our clinic. After a complete ocular examination, each patient’s IOP was measured and recorded with GAT and iCare HOME2. Central corneal thickness was measured. Eyes with any corneal morbidity were excluded. Pearson correlation coefficient was used to determine the correlation between paired IOP measurements. Bland-Altman plots were graphed for the analysis of differences in IOP between the instruments. Results: One hundred thirty-five eyes of 70 patients were included in the study. The mean IOP measured with GAT was 16.3 ± 6.5 mm Hg (range: 3–56). The mean IOP measured with iCare HOME2 was 16.5 ± 7.3 mm Hg (range: 3–55), (P = 0.47). A strong, significant positive correlation was found for paired IOP measurements by the 2 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, whereas it overestimated IOPs when corneas were thicker than this. Conclusion: The iCare HOME2 could be a reliable tonometer for most eyes and clinical settings. Central corneal thickness measurement is recommended in patients who use the instrument.