Spectral sensitivity for observers with protanomalous, extreme protanomalous and protanopic colour vision.

Contemporary models of colour vision include a channel for luminosity arising from a combination of some or all of the cone outputs. Accordingly any alteration, reduction or loss at the cone level ought to affect the shape of the spectral sensitivity curve, yet there have been few reports of any significant differences being found between the curves of protanomalous and protanopic subjects. A modified minimum flicker technique was used to determine the spectral sensitivity curves of observers with protanomalous, extreme protanomalous and protanopic vision. Significant differences were found among the mean curves of these categories of vision from 550 nm upwards.