Abstract
Purpose :
The calibration-free eye tracker is equipped with a face recognition function that allows the examinee to start eye tracking when they sit on the device. We attempted to measure visual acuity automatically by combining this device with vertical stripe targets and investigated visual axis retention time at each spatial frequency of a visual stimulus.
Methods :
A total of 44 eyes from 22 healthy participants (mean age: 20.2 years ± 0.7 years) were included in this study. The mean spherical equivalent of the right and left eyes were −4.6 D ± 2.2 D (range: −10.25 D to −1.5 D) and −4.5 D ± 2.2 D (range: −10.1 D to -1.5 D), respectively. Participants with visual field defects detected by a Humphrey field analyzer (24-2 Swedish Interactive Threshold Algorithm Fast Strategy) or with abnormal eye positions were excluded. Participants were seated in front of a calibration-free eye tracker (EMR ACTUS, Nac Image Technology, Tokyo, Japan) with an integrated monitor and freely observed a vertical stripe stimulus. Three types of stimuli (8.4, 12.9, and 25.8 cycles/degree [c/d]) were presented three times each. Areas of Interest (AOI) were set on the stripes, and the percentage of visual axis retention time in the AOI during the presentation of the stimuli was measured. A one-way repeated analysis of variance was used to compare the percentage of visual retention time for each stimulus. P values of less than 0.05 were considered significant.
Results :
Among the 44 eyes, one (2.2%) was excluded from the analysis because of measurement error. The mean retention time per stimuli of the right eye were 79.9% ± 22.2%, 72.3% ± 27.9%, and 58.2% ± 30.7% at 8.4 c/d, 12.9 c/d, and 25.8 c/d, respectively, which were all statistically significantly different (F = 12.9, p < 0.01). In the left eye, the mean retention time per stimuli were 79.5 ± 22.7%, 77.4% ± 24.8%, and 61.0% ± 28.5% at 8.4 c/d, 12.9 c/d, and 25.8 c/d, respectively, which were all statistically significantly different (F = 9.1, p < 0.01). In both eyes, the percentage of visual axis retention time decreased with increasing spatial frequency.
Conclusions :
The correct responses declined with the increasing spatial frequency even with the stripes displayed on the eye tracker. Further studies with a greater number of cases are needed to examine the correlation between LogMAR visual acuity and refractive error.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.