Effects of Target Size and Test Distance on Stereoacuity

Iwata, Yo; Fujimura, Fusako; Handa, Tomoya; Shoji, Nobuyuki; Ishikawa, Hitoshi

doi:10.1155/2016/7950690

Cited by 4 publications

(2 citation statements)

References 35 publications

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“…These might be an effect of different circle size and viewing distance. 20 The results demonstrate high sensitivity of Titmus for distance VA, near VA and color perception. These results are relevant to a previous study by Horberry TJ et al, 21 which found that Titmus had overall 82.1% sensitivity and 62.5% specificity.…”

Section: Discussionmentioning

confidence: 73%

Validity of Vision Screener among Workers in a Private Hospital in the Northern Part of Thailand

Teerasantipun¹,

Pichetweerachai²,

Theerakul³

et al. 2019

bkkmedj

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any occupations require people to have sufficient visual performance to be able to work effectively and safely. Some jobs require high levels of visual function, such as operation of heavy moving machinery. Truck drivers must have normal color perception in order to perceive colored signals correctly, and so as electricians. Some specific tasks, such as working in a confined space, have standards regulated by law. 1,2 These requirements are known as occupational vision standards. The important law that provides requirements, guidelines, and standards with which employers must comply is the Ministerial Regulation on the Prescribing of Criteria and Method of Conducting Health Checkup of Employees and Forwarding the Results of Health Checkup to Labour Inspector B.E. 2547 (2004), 2 Labour Protection Act B.E. 2541 (1998), administered by Thai Department of Labour. Furthermore, there are laws that offer standards for special tasks which require visual performance tests such as Ministerial Regulation on the Prescribing of Standard for Administration and Management of Occupational Safety, Health and Work Environment in Confined Space B.

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Section: Discussionmentioning

confidence: 73%

Validity of Vision Screener among Workers in a Private Hospital in the Northern Part of Thailand

Teerasantipun¹,

Pichetweerachai²,

Theerakul³

et al. 2019

bkkmedj

View full text Add to dashboard Cite

show abstract

“…Previous studies have reported conflicting results between stereo thresholds and viewing distances. Some reported no correlation between stereo threshold and testing distances [29], while others found a more superior stereopsis at far [30]. Nonetheless, these results vary with the types of tests.…”

Section: Discussionmentioning

confidence: 99%

Assessment of depth perception with a comprehensive disparity defined letter test: A pilot study

Lew

Coates

2022

PLoS ONE

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Current clinical tests mostly assess stereopsis with crossed disparity at near. These tests are designed with fine targets (high spatial frequency) and may fail to capture the “functional stereopsis” in real-world scenes, which consist of a range of spatial frequencies (SFs). We developed a stereo letter test that can assess crossed and uncrossed stereoacuity at near and far, at different SFs defined by the letter size. The test consists of disparity-defined letters embedded in random-dot stereograms. At each letter size, the letters are arranged in sets of trigrams like in the Pelli-Robson chart. The letter sizes correspond to SFs ranging from 0.3 to 2cpd. Within each triplet, all letters have the same disparity and the amount of disparity decreases after each set. Subjects report the letters verbally to determine the smallest disparity at each letter size. Twenty-four subjects were tested with eight different charts: crossed vs. uncrossed disparity at far and near, with two versions (different letter sequences). The disparity sensitivity function (DSF) had an inverted U-shape, with decreasing sensitivity for smaller stereo letters. The subjects had better stereopsis at far than near. All the subjects had lower stereo thresholds with crossed disparity than uncrossed, consistently at both distances. We found no effect of age or heterophoria on the DSF. The charts have good test-retest reliability (Pearson’s r = 0.89, p<0.001) and are easy to perform. Our results with stereo letters as stimuli are comparable to results from studies using depth corrugations. This stereo acuity letter test permits assessment of stereopsis at different testing distances, directionality of disparity, and across a range of SFs, which can help diagnose selective stereo losses in binocular vision anomalies and monovision. Assessment of stereopsis at different SFs may provide additional information for understanding daily stereovision demands than the conventional tests.

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Study on stereoacuity and associated factors in school children aged 7 to 14 years

Potluri

Akella²,

Mallidi³

et al. 2021

Indian Journal of Ophthalmology

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Purpose: The study aimed to estimate the prevalence of subnormal stereoacuity in school children and to assess the factors associated with it. Methods: In this prospective cross-sectional study, a total of 2,376 school children without amblyopia and manifest squint were screened by the titmus fly test, Snellen chart, tests for heterophoria, anterior segment examination, and fundoscopy. Children with a manifest squint, amblyopia (best-corrected visual acuity [BCVA] <6/18), and history of ocular trauma or surgery, and one-eyed children were excluded. Cycloplegic refraction was done in children with uncorrected or undercorrected refractive errors, and stereoacuity was assessed again with spectacle correction. Results: The prevalence of normal stereoacuity by titmus fly test was 93.18% with correction of refractive errors. Girls had slightly better stereopsis compared with boys. The subnormal stereoacuity was significantly associated with refractive error ( P < 0.00001, significant at P < 0.05), unilateral refractive error ( P < 0.00001, significant at P < 0.05), bilateral refractive error ( P < 0.00001, significant at P < 0.05), anisometropia ( P < 0.00001, significant at P < 0.05), ametropia ( P < 0.00001, significant at P < 0.05), lower BCVA ( P < 0.00001, significant at P < 0.05), hyperopia ( P < 0.05, significant at P < 0.05), and heterophoria ( P = 0.014, significant at P < 0.05). The subnormal stereoacuity was positively correlated with the magnitude of refractive error of the eyes. Conclusion: This study underlines the significant impact of identification and correction of refractive errors and squints in school children. The measurement of stereoacuity will be of immense importance and must be included in the screening programs for children.

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Effects of Target Size and Test Distance on Stereoacuity

Cited by 4 publications

References 35 publications

Validity of Vision Screener among Workers in a Private Hospital in the Northern Part of Thailand

Validity of Vision Screener among Workers in a Private Hospital in the Northern Part of Thailand

Assessment of depth perception with a comprehensive disparity defined letter test: A pilot study

Study on stereoacuity and associated factors in school children aged 7 to 14 years

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