Anomalous Trichromat

A person who has all three types of cone cells in the retina but one type has a shifted spectral sensitivity, causing altered colour perception that is less severe than dichromacy. Anomalous trichromats include protanomalous individuals (shifted L-cones, reduced red sensitivity), deuteranomalous individuals (shifted M-cones, reduced green sensitivity), and tritanomalous individuals (shifted S-cones, reduced blue sensitivity). Deuteranomaly is the most common form of colour vision deficiency, affecting approximately 5% of males. Anomalous trichromats can often distinguish more colours than dichromats but fewer than people with typical colour vision.