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Allen figure and broken wheel visual acuity measurement in preschool children
1Exceptional Child and Infant Vision Testing Laboratory, Ohio State University, College of Optometry, Columbus 43210.
Insights
The Broken Wheel test offers more consistent visual acuity measurements in preschool children than the Allen figure test. This makes the Broken Wheel a valuable clinical tool for assessing young children's vision.
Area of Science:
- Ophthalmology
- Pediatric Optometry
- Vision Science
Background:
- Accurate visual acuity measurement in preschool children is crucial for early detection of vision impairments.
- Existing methods like the Allen figure test may lack consistency, potentially leading to misdiagnosis or delayed intervention.
Purpose of the Study:
- To compare the reliability and consistency of the Broken Wheel test versus the Allen figure test for measuring visual acuity in preschool children.
- To determine the clinical utility of the Broken Wheel test as a tool for assessing visual acuity in young children.
Main Methods:
- A masked investigation was conducted with 34 preschool children (ages 3-5) from Project Headstart.
- Monocular and binocular visual acuity were measured using both the Broken Wheel and Allen figure tests.
- Statistical correlation analyses (Pearson's r and Spearman's rho) were performed to compare test results.
Main Results:
- The Allen figure test yielded a wider range of acuity values compared to the Broken Wheel test, despite similar Snellen equivalents.
- No strong statistical correlation was found between the two tests (e.g., rOD = +0.22, rOS = -0.11).
- The Broken Wheel test demonstrated higher consistency in discriminating between 20/30 and 20/40 acuity levels (p ≤ 0.003) and showed good test-retest reliability.
Conclusions:
- The Broken Wheel test is a more consistent and reliable method for measuring visual acuity in preschool children compared to the Allen figure test.
- Despite minor variations from Snellen standards (+/- 5.6%), the Broken Wheel test is a valuable clinical tool for pediatric vision screening.
Abstract:
In a masked investigation, 34 preschool children (n = 34, 19 females and 15 males) between the ages of 3 and 5 years (mean age = 4.1 years) enrolled in Project Headstart had their monocular and binocular visual acuity measured using the Broken Wheel and Allen figure methods. The results showed that 1) a greater range in acuity values was found with the Allen figure than Broken Wheel test, despite the identical Snellen equivalent acuity levels and similar probability of guessing criteria used for both Broken Wheel and Allen figure acuity measurement e.g., no strong statistical correlation (rOD = +0.22, rOS = -0.11 and rOU = +0.04; rho OD = +0.22, rho OS = -0.11, rho OU = 0.00) for the two tests was found; and 2) the Broken Wheel test appeared to discriminate between 20/30 and 20/40 acuity performance more consistently than did Allen figure and in a way not attributable to chance (p less than or equal to 0.003). In a separate evaluation, the Broken Wheel test showed consistency in the acuity measured. Broken Wheel acuity measurement, even with an average variation of +/- 5.6 percent from the corresponding Snellen standard, appears to be a valuable clinical tool to measure acuity in young children.