Evidence-Based Comparisons: LEA Symbols vs. Other Vision Tests
Selecting the appropriate test for pediatric screening has a direct impact on whether vision problems are detected early or missed entirely. While many vision charts are available, research and clinical guidelines consistently show that not all tests perform equally when used with young children. Understanding these differences is essential for effective preschool and early school-age screening.
Comparing vision screening tests used in children
Traditional Snellen letter charts and number charts are still used in some settings, but they are appropriate only for children aged six years and older who are familiar with letters or numbers. In younger children, these charts may overestimate visual acuity because children guess based on familiar shapes rather than true visual resolution. As a result, vision problems may go undetected during critical developmental years.
HOTV charts were developed to make letter-based testing more accessible for children, using only four letters. While HOTV tests are easier than full Snellen charts, they still require letter recognition and may be confusing for very young preschoolers. Clinical guidelines therefore recommend HOTV only alongside validated picture optotypes for preschool screening.
LEA Symbols compared with other picture charts
The Sheridan-Gardiner (SG) chart uses seven letters that children must match on a response card. In a randomized study of 260 preschool children, the LEA Symbols chart demonstrated a sensitivity of 94.74 percent, compared with only 52.63 percent for the SG chart. Although the SG chart showed higher specificity, its lower sensitivity means that a greater number of children with vision problems may be missed during screening.
Additional studies have reported similar findings. In Malaysian preschool populations, LEA Symbols achieved a sensitivity of 97.5 percent, compared with 57.1 percent for the SG chart. These results highlight why sensitivity is a critical factor in pediatric screening, where the goal is to identify children who require further evaluation.
Other picture-based tests, including Allen figures, Tumbling E, Lighthouse symbols, and the Hand Chart, present additional challenges. Some rely on directional understanding or fine motor responses, combining visual and motor skills in ways that can produce inaccurate results. Many of these charts lack standardization or peer-reviewed validation and are no longer recommended in preschool screening guidelines.
Comparisons with Kay, Patti Pics, and Oculus charts
The Kay Picture Test is marketed as a validated picture visual acuity test and uses recognizable objects such as a boot, duck, and house. Research from Liverpool University reports good testability and sensitivity, particularly in young children and those with learning disabilities. Patti Pics charts emphasize colorful, stylized figures and claim calibration to Sloan standards, while Oculus offers a range of letter, numeral, and picture charts with defined acuity ranges.
These tests may have specific applications, but professional guidelines continue to identify LEA Symbols and HOTV letters as the only picture optotypes recommended for preschool screening. Importantly, Lighthouse International itself transitioned to LEA Symbols in 1991, reflecting broader recognition of the need for standardized, validated pediatric optotypes.
Unique benefits of LEA Symbols in screening programs
When selecting tools for pediatric screening, the advantages of LEA Symbols extend beyond a single acuity chart. Their design and system-based approach support accurate screening across a wide range of ages and abilities.
- Standardized optotype design: LEA Symbols are among the few picture charts calibrated against recognized standards such as the Snellen E and Landolt C. Each symbol blurs equally at threshold, reducing guessing and improving measurement consistency.
- High sensitivity for detecting vision problems: Comparative studies show LEA Symbols achieve significantly higher sensitivity than many other picture charts, helping ensure that children who need referral are identified during screening.
- Support for early and diverse screening: LEA tests are designed for use with very young children and those with developmental delays, neurological conditions, or limited communication abilities.
- Multiple test formats: The LEA Test System includes distance and near acuity charts, contrast sensitivity testing, color-vision assessment, and cognitive vision tools, supporting comprehensive pediatric screening.
- Assessment from infancy: Puzzle-based and preferential-looking formats allow screening of children as young as 14 months, enabling earlier identification of amblyopia and other vision conditions.
By supporting earlier and more accurate screening, LEA Symbols help reduce missed diagnoses and improve opportunities for timely intervention during critical stages of visual development.
Conclusion
When comparing pediatric vision screening tools, evidence and guidelines provide clear direction. Research consistently shows that LEA Symbols outperform many other picture-based tests in sensitivity and reliability. National and international guidelines recommend LEA Symbols, alongside HOTV letters, and advise against the use of non-standardized charts in preschool screening.
By selecting evidence-based tools designed for young children, screening programs can reduce missed diagnoses and support healthy visual development during the years when intervention is most effective.
