The cornea :
The front transparent part of the eye, protective envelope of the sclera or the white of the eye.
The iris :
Rear part of the choroid, rich in colouring materials and blood vessels. This is the eye nourishing tissue. It contracts or expands depending on the light intensity.
The pupil :
opening at the center of the Iris, the diameter of which increases or reduces depending on the light intensity.
The retina :
Nervous membrane at the back of the eye. The retina captures light rays and sends them to the brain through the optic nerve.
The lens :
Bi-convex transparent lens about 9 mm diameter. It is composed of flexible fibres laid out in layers, and forces light rays to converge onto the retina to give focused vision. The lens may become opaque, and may necessitate a cataract operation which removes the lens.