2023 Volume 53 Pages 71-78
【Purpose】We developed a new method to measure a subject's visual acuity when he or she walked towards an optotype (“visual acuity while walking”) and examined the repeatability of the measurement.
【Subjects and Methods】Subjects were 44 young (average age, 21.1 years) and 25 middle-aged and elderly (average age, 57. 9 years) participants. After correction of distance refraction, static visual acuity (SVA) and visual acuity while walking were measured under binocular viewing with 100% and 25% optotype contrasts. The subject walked towards a Landolt ring (for decimal visual acuity 0.7 at 5 m) 20 m ahead. Visual acuity while walking based on the time of response (response visual acuity) that used the distance between the response point and the optotype and visual acuity while walking based on the time of perception (perception visual acuity) that included a reaction time of 0.3 seconds were assessed. A guide walked next to the subject and instructed on the stride length and pace to keep the subject's walking speed at about 2, 3, and 4 km/h. Two measurements were taken at random for each test condition and the average of the two measurements was used. To examine the measurement repeatability, intraclass correlation coefficients (ICCs) and Bland-Altman analysis were used.
【Results】Both ICCs (0.85～0.92) and Bland-Altman analysis showed a high measurement repeatability of visual acuity while walking in the two age groups. At 100% and 25% optotype contrasts, SVA was higher than response and perception visual acuity in both age groups.
【Conclusions】This method could quantify visual acuity while walking with high repeatability.
