In dark adaptation, there is:
In dark adaptation, there is re-synthesis of the bleached rhodopsin. In the retina, the storage form of vitamin A (all-trans retinol) is conveed to 11-cis retinal which combines with opsin to form rhodopsin. Initial dark adaptation is due to cones; cones form visual pigment faster as compared to rods. Other changes in the dark: (1) dilation of pupil, (2) increased number of impulses in the optic nerve fibers.
Break down of rhodopsin
Increased threshold for vision
No role for cones
No change in the dioptric power of the eye
Special Senses