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Visual acuity of the preschool child: a review
Insights
Standardized visual acuity norms are needed for preschool children. A well-designed test uses high-contrast optotypes and matching responses, with STY-CAR being the closest standardized option.
Area of Science:
- Ophthalmology
- Pediatric Optometry
- Vision Science
Background:
- Visual acuity assessment is crucial for preschool children.
- Current lack of standardized visual acuity norms and screening criteria poses challenges.
Purpose of the Study:
- To review literature on distance visual acuity in preschool children.
- To identify optimal design principles for preschool visual acuity tests.
Main Methods:
- Literature review of visual acuity assessment methods, norms, and screening criteria.
- Analysis of testability and design principles for preschool vision tests.
Main Results:
- No standardized visual acuity norms or screening criteria currently exist for preschoolers.
- Recommended test design: high-contrast Snellen optotypes, no directional elements, 0.1 log steps to 6/3.
- Matching or forced-choice responses improve testability.
Conclusions:
- The STY-CAR (Sheridan-Gardiner) test most closely meets the recommended criteria for preschool visual acuity testing.
- Development of standardized, well-designed visual acuity tests is essential for early detection of vision problems.
Abstract:
The need for visual acuity assessment in preschool children has long been recognized, yet there are no standardized visual acuity norms or screening criteria. This report reviews the literature on distance visual acuity in the preschool child. The areas of review include: methods of assessment of visual acuity; visual acuity norms obtained with these tests; reasons for the variations in reported visual acuity norms; variations in referral criteria for vision screenings; testability reported for various visual acuity tests; and important design principles and recommendations for preschool visual acuity tests. It is concluded that a well designed preschool visual acuity test should consist of high contrast Snellen optotypes without directional components that progress in 0.1 log steps down to a level of 6/3. To improve testability, a matching or forced choice response should be used. Of the tests that have been standardized, STY-CAR (Sheridan-Gardiner) comes closest to meeting these criteria.