Empirical tests of the effectiveness of EnChroma multi-notch filters for enhancing color vision in deuteranomaly.

Manufacturers of notch filter-based aids for color vision claim that their products can enhance color perception for people with anomalous trichromacy, a form of color vision deficiency (CVD). Anecdotal reports imply that people with CVD can have radically enhanced color vision when using the filters. However, existing empirical research largely focussed on the effect of notch filters on performance on diagnostic tests for CVD has not found that they have any substantial effect.

Predicted effectiveness of EnChroma multi-notch filters for enhancing color perception in anomalous trichromats.

EnChroma filters are aids designed to improve color vision for anomalous trichromats. Their use is controversial because the results of lab-based assessments of their effectiveness have so far largely failed to agree with positive anecdotal reports. However, the effectiveness of EnChroma filters will vary depending on the conditions of viewing, including whether the stimuli are broadband reflective surfaces or colors presented on RGB displays, whether illumination spectra are broadband or narrowband, the transmission spectra of particular filters, and the cone spectral sensitivity functions of the observer.

Screening for mild anomalous trichromacy using the Ishihara plates test.

The Ishihara plates test is one of the most established and widely used means of identifying color vision deficiencies. However, literature examining the effectiveness of the Ishihara plates test has identified weaknesses, particularly when screening for milder anomalous trichromacy. We constructed a model of the chromatic signals expected to contribute to false negative readings by calculating, for particular anomalous trichromatic observers, the differences in chromaticity between the ground and pseudoisochromatic portions of plates.