Cornea - It is transparent and the light enters through cornea. The light rays in visible wavelength are focused on the retina through the cornea and lens generate potentials (impulses) in rods and cones.
Iris and pupil - The iris serves this purpose. It is a disc-like colored membrane lying between the cornea and the lens. It controls the amount of light entering the eye by regulating pupil dilation. In dim light the pupil dilates; in bright light it contracts.
Optic Lens - The lens focuses the light on the retina.
Retina - The inner-most, light sensitive layer of the eyeball, on which images are formed. They contain Photo-receptors which are light-sensitive cells and hence can detect light stimulus.
Optic nerve - The Optic Nerve is located at the back of the eye. It transmits nerve impulses from photo-receptors to the brain.
Ciliary muscles - Ciliary Muscles that adjusts the curative of the Lens. Ciliary Muscles determines the shape of the Lens.
Power of Accommodation. The process by which the ciliary muscles change the focal length of an eye lens to focus distant or near objects clearly on the retina is called the accommodation of the eye.