vision

the capacity for sight. Light enters the EYE through the CORNEA and the aqueous HUMOUR . Next, it passes through the PUPIL , LENS and VITREOUS HUMOUR to impinge upon the RETINA . There the ROD and CONE cells detect light and send impulses to the nerve fibres, which are relayed to the visual cortex in the BRAIN via the optic nerve. Visual acuity is the sharpness of vision, dependent on a healthy retina and accurate lens. See also SNELLEN CHART .