Pupillary reflex to red light and white light

Red monochromatic light going through the eye pupil in the range of 610-760nm causes no pupillary constriction. Hitting eye pupil 7438K CCT white light with peak in blue 444nm causes a rapid contraction of the pupil.

Narrowing and broadening of the pupil is the job of ganglion cells. Besides other functions, their sensitivity is the strongest in the 460-480nm range. On monochromatic red light more than 600nm, ganglion cells do not respond as well as rhodopsin in rods.