A Novel Method for Hyperacuity Measurement

Jin Ha Kim; Key Hwan Lim; Yun Taek Kim

doi:10.3341/jkos.2020.61.2.175

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Kim, Lim, and Kim: A Novel Method for Hyperacuity Measurement

Original Article

Journal of the Korean Ophthalmological Society 2020; 61(2): 175-182.

Published online: 18 February 2020

DOI: https://doi.org/10.3341/jkos.2020.61.2.175

A Novel Method for Hyperacuity Measurement

Jin Ha Kim, MD¹, Key Hwan Lim, MD, PhD¹, Yun Taek Kim, MD, PhD²

¹Department of Ophthalmology, Ewha Womans University College of Medicine, Seoul, Korea.

²Cheonan Kim's Eye Clinic, Cheonan, Korea.

Address reprint requests to Yun Taek Kim, MD, PhD. Cheonan Kim's Eye Clinic, #92 Jungang-ro, Dongnam-gu, Cheonan 31127, Korea. Tel: 82-41-551-1082, Fax: 82-41-555-2051, jjongofhim@hanmail.com

Received 2 September 2019 Revised 24 October 2019 Accepted 17 January 2020

The Korean Ophthalmological Society

(open-access):

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose

We developed a novel method for measurement of hyperacuity and verified the utility thereof.

Methods

We developed a three-dimensional (3D) hyperacuity test using a 3D liquid crystal flat screen, a left- and right-image polarized display, and liquid crystal shutter glasses. We tested the technique in three groups: normal (n = 48), with cataracts (n = 14), and with macular disease (n = 35). We used a chart consisting of five dots and a reference line. Of the five dots, one was variably shifted from the other dots. A chart was presented to one eye and the reference line or blank image to the other eye; a subject scored positive when the dot in the unusual position was recognized.

Results

Hyperacuity was measured in terms of the reference line seen by the reference eye (RR), a blank image seen by the reference eye (RB), the reference line seen by the contralateral eye (CR), and a blank image seen by the contralateral eye (CB). All test scores were significantly lower when the reference line was seen than not (RR vs. RB and CR vs. CB; p < 0.01, respectively). For the RR and CR tests, no significant difference was apparent between the normal and cataracts group (p = 0.553, p = 0.494) but such differences were evident between the normal and macular disease groups (p = 0.028, p = 0.002). Also, visualization of the reference line by the reference and contralateral eyes did not differ (p > 0.05).

Conclusions

Measurement of hyperacuity using our new method was not affected by media opacity but was significantly affected by macular disease. Presentation of a reference line facilitated hyperacuity assessment.

Keywords: Hyperacuity, Vernier acuity, 3-Dimensional hyperacuity test

Figures and Tables

Figure 1

Actual measurement of hyperacuity. For binocular vision separation, the target was projected onto a polarization monitor and the subject wore polarized glasses (3 dimensional glasses) orthogonal to both eyes.

Figure 2

Chart developed for hyperacuity measurement. It consists of target images which consist of 5 dots with reference line and without reference line. When subject wears 3 dimensional (3D) glasses and looks at the target, it looks like a 3D image. RR = reference eye has a reference line and dots on the contralateral eye; RB = reference eye has a blank image and dots on the contralateral eye; CR = reference eye has dots and reference line on the contralateral eye; CB = reference eye has dots and blank image on the contralateral eye.

Figure 3

Chart developed for hyperacuity measurement. This image consists of five dots. Randomly one of five dots is out of baseline. Grades are from 6 to 1, and are indicated at the upper left of each chart. Each grade means that the deviation is from 6 pixel to 1 pixel from the baseline. In the figure above, grade 6 (the first chart on the left) is a dot 6 pixel away from the baseline, which corresponds to the third dot (The downwards arrow points to the dot that is out of the baseline, which does not appear in the actual chart).

Figure 4

Difference in hyperacuity with or without reference line. The analysis was divided into two cases: Reference line on the reference eye (A) and the contralateral eye (B). All groups can detect more sensitively than when there is no reference line (all p < 0.05). p-value is obtained from Wilcoxon signed rank test. RR = reference eye has a reference line and dots on the contralateral eye; RB = reference eye has a blank image and dots on the contralateral eye; CR = reference eye has dots and reference line on the contralateral eye; CB = reference eye has dots and blank image on the contralateral eye.

Figure 5

Difference in hyperacuity by group. Normal group and cataract group showed no difference in hyperacuity, but normal group and macular disease showed significant differences in RR (p = 0.028) and CR (p = 0.002). p-value is obtained from Mann-Whitney U test. RR = reference eye has a reference line and dots on the contralateral eye; RB = reference eye has a blank image and dots on the contralateral eye; CR = reference eye has dots and reference line on the contralateral eye; CB = reference eye has dots and blank image on the contralateral eye.

Figure 6

Difference in hyperacuity depending on site of reference line. There is no difference in the hyperacuity when the reference line is in the reference eye or contralateral eye. p-value is obtained from Wilcoxon signed rank test. RR = reference eye has a reference line and dots on the contralateral eye; CR = reference eye has dots and reference line on the contralateral eye.

Table 1

Demographics of the study

Values are presented as mean ± standard deviation or number.

RR = reference eye has a reference line and dots on the contralateral eye; RB = reference eye has a blank image and dots on the contralateral eye; CR = reference eye has dots and reference line on the contralateral eye; CB = reference eye has dots and blank image on the contralateral eye.

^*p-value is obtained from chi-square statistics for sex and other is calculated by analysis of variance.

Table 2

Difference in hyperacuity with or without reference line

All groups can detect more sensitively than when there is no reference line. Values are presented as mean ± standard deviation.

^*p-value is obtained from Wilcoxon signed rank test.

Table 3

Difference in hyperacuity by group

Normal group and cataract group showed no difference in hyperacuity, but normal group and macular disease showed significant differences in RR and CR. Values are presented as mean ± standard deviation.

Macular ds. = macular disease; RR = reference eye has a reference line and dots on the contralateral eye; RB = reference eye has a blank image and dots on the contralateral eye; CR = reference eye has dots and reference line on the contralateral eye; CB = reference eye has dots and blank image on the contralateral eye.

^*p-value is obtained from Mann-Whitney U test.

Notes

^{Conflicts of Interest} The authors have no conflicts to disclose.

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