A Modified Protocol for Color Vision Screening Using Ishihara

Color vision screening is a routine part of medical and occupational evaluations. The Ishihara test is widely used to detect red-green color deficiencies. However, some individuals with normal color vision may fail the test due to unfamiliarity or test design. This leads to unnecessary follow-up testing. The European Aviation Safety Agency requires stricter standards than the original Ishihara guidelines. These changes increase the false positive rate significantly. No prior work had resolved this issue effectively. This gap motivated the investigation of protocol modifications. The goal was to reduce false positives without compromising test accuracy.

This study aimed to evaluate two changes to the Ishihara test protocol. The first modification allowed a second attempt for minor errors. The second involved rotating the test plates. The researchers wanted to determine if these changes could lower the false positive rate. They also sought to maintain the test’s ability to detect true color deficiencies. The motivation came from the high false positive rate reported under current standards. Reducing unnecessary advanced testing was a key objective. The study focused on occupational screening requirements. The findings could improve the reliability of initial color vision assessments.

The study tested two protocol modifications. The first allowed a second attempt for minor errors. The second involved rotating the Ishihara plates. Researchers compared the false positive rates before and after these changes. They used a sample of subjects with normal color vision. The test conditions followed EASA guidelines. Plate rotation was applied to specific Ishihara plates. Error rates were recorded for each condition. The results were analyzed to assess the impact of the modifications.

The modified protocol reduced the false positive rate to 5.9%. This is a significant decrease from the previously reported 50%. The second attempt modification had the most impact. Rotated plates did not affect correct identification rates. These findings suggest the changes improve test accuracy. The results were consistent across all test conditions. No significant differences were found between rotated and standard plates. The study supports the use of these modifications in occupational screening.

The authors propose that the modified Ishihara protocol reduces false positives. They suggest that allowing a second attempt improves test fairness. Rotating plates maintains diagnostic accuracy. The changes align with EASA requirements. The study supports the use of these modifications in practice. These adjustments may reduce unnecessary follow-up testing. The findings are specific to the test conditions described. The authors do not claim broader generalizations.