Normal color vision, predicated on three cones sensitive to red, green, and blue light, is essential for critical color discrimination in multiple occupations. Yet 8% of males and 0.5% of females have hereditary X-linked color vision deficiency (CVD): red or green cones are absent (2%) or peak sensitivity of defective cones are shifted in wavelength [1]. A novel approach using color-correcting lenses (CCLs) with notch filters improved suprathreshold red-green perception in CVDs after extended wear even without viewing through CCLs [2]. We used cone specific tests (contrast sensitivity, CS [3], visual evoked potentials, VEPs [4], color naming) to demonstrate immediate and long-term threshold and supra-threshold improvements in CVDs with CCLs.

Thirteen CVDs (9 green/deuteranomalous, 4 red/protanomalous, mean age 32 ± 14, range 13-66; CVD confirmed by Ishihara, anomaloscope, cone CS tests) provided informed consent to participate (repeated measures, before-after design). Each subject was given a CCL appropriate for their CVD (www.enchroma.com) and tested with and without CCLs at baseline and 11–14 days later after wearing the CCLs daily (mean h/day: 2.5 ± 1.8). Cone CS [3] and color naming were assessed by presenting letters visible only to red, green, or blue cones and gray luminance letters on a Surface Pro in randomized order within and between sessions. Subjects verbally identified each letter and its color with scoring (0–100) based on letters correct (0.15 log CS/letter). Cone specific VEPs [4] were recorded to an average of 75 pattern onsets without and with CCLs.

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