Comparison of head-mounted perimeter (imo^®) and Humphrey Field Analyzer

The head-mounted automated perimeter imo^® is a new portable perimeter that does not require a dark room and can be used to examine patients in any setting. In this study, imo 24plus (1-2) AIZE examinations were compared with previous Humphrey Field Analyzer (HFA) 30-2 (SITA standard) examinations within the same patient.

imo examinations (either head-mounted [i-H] or fixed [i-F] type) were performed in patients with glaucoma or suspected glaucoma who had already experienced HFA five or more times. Measurement time and correlations of mean deviation (MD) and visual field index (VFI) values were compared between groups for HFA, i-H, i-F, and imo total (i-T). Fixation loss (FL), false-positive (FP), and false-negative (FN) detection rates were compared. The percentage of binocular random single-eye tests under possible non-occlusion conditions using imo was determined. Mann-Whitney U test was performed, and Spearman's rank-order correlation coefficient was calculated.

The inclusion period was July to December 2016. Among 273 subjects (543 eyes), 147 (292 eyes) were tested with i-H type and 126 (251 eyes) with i-F type. Mean MD values for HFA and i-T were -6.1±7.8 and -6.2±7.1 dB, respectively. Mean measurement times for HFA, i-H, i-F, and i-T were 15.23±2.07, 10.47±2.11, 11.04±2.31, and 10.54±2.19 minutes, respectively (P<0.01 for HFA vs i-H/i-F). Total mean measurement time was shorter by 30.8% for i-T vs HFA. Correlation coefficients of MD and VFI were R ²>0.81 for HFA vs i-H and i-F. FP and FN detection rates were significantly higher with i-T than HFA; there was no significant difference in FL. Binocular random single-eye tests were possible in 85% of cases.

imo reduced measurement time by 30.8%. imo VFI and MD values were highly correlated with HFA. As i-F and i-H types produced similar results, imo can be used in accordance with the patient's situation.