Efficacy of red contact lens in improving color vision test performance based on Ishihara, Farnsworth D15, and Martin Lantern Test

Background

The aim of this study was to evaluate the efficacy of red contact lens in improving color vision test performance based on Ishihara, Farnsworth D15, and Martin Lantern Test (MLT).

Methods

Thirty subjects with a known color vision defect were enrolled after consent. The color vision was assessed using Ishihara test, D15 test, and MLT. The error scores were recorded. The test was repeated after using a red contact lens.

Results

The mean error scores were 7.87 (±1.00), 3.33 (±3.15), and 5.67 (±2.52) on Ishihara, MLT, and D15 test, respectively. The error scores reduced to 3.93 (±3.78), 1.33 (±1.34), and 2.77 (±2.12) Ishihara, MLT, and D15 test, respectively (P value < 0.05, Wilcoxon rank test). None of the subjects were in color perception (CP) II at presentation but 47.5% became CP II with the lens on Ishihara test. Ninety percent could pass the MLT CP III standard.

Conclusion

This study shows that red lens reduced error scores and subjects could pass the color vision tests. Notwithstanding the improvement in performance on color vision tests, lens is not recommended for personnel on active combat duty. The recruiting medical officer needs to be aware of the fact that a subject with defective color vision can pass various tests with a red contact lens.