The mechanism of vision:

i. The light rays in visible wavelength is focussed on the retina through the cornea and lens generate potentials (impulses) in rods and cones.

ii. The photopigments which is composed of opsin and retinal is dissociated into opsin and retinal because of light. .

 iii. The change in the structure of the opsin causes changes in the membrane permeability.

iv. A potential differences is generated in the photoreceptor cells which produces signal that generating action potentials in the ganglion cells through the bipolar cells.

v.  The action potential is transmitted by the optic nerves to the visual cortex area of the brain, where the neural impulses are analysed and the image is formed on the retina is recognised.