The eye is one of the most unique parts of the body in both structure and function. It has visible and hidden parts and is much larger than it appears. When you look into a person’s eyes you see the cornea, sclera, iris, and pupil. The lens, retina, and optic nerve are not visible, but your ophthalmologist has ways of seeing them.
What You See
The cornea is the clear front surface of your eye. The cornea refracts (bends) light as it passes into your eye and is responsible for about 60% of focusing. The cornea is the part of your eye that is reshaped by LASIK surgery.
The sclera is the white of your eye. The iris is the colored part. It is actually a muscle. And the pupil is nothing at all. It is the opening in the center of the eye – empty space.
What You Cannot See
The lens of your eye is behind the pupil where it is not visible. Some people think that the cornea is the same thing as the lens. The cornea is a lens, but it is not “the” lens. The lens of your eye bends and flexes changing curvature to fine tune the focus of the light that has passed through the cornea. The lens can be replaced with an artificial lens (IOL) to correct problems such as cataracts and presbyopia.
The retina is the back wall of the eye. It contains three types of light sensitive cells. The optic nerve connects just off the center of the retina and contains fibers that run to each of the photosensitive cells in the retina. The optic nerve relays messages between the eye and the brain.