About the eye

Sharp vision depends on many factors. The parts of the
eye work together to refract (bend and focus) light rays.
If the cornea or the eyeball as a whole is not the right
shape, light doesn’t focus correctly, and vision is blurry.

The cornea is the eye’s clear, dome-shaped
window.

The thin outer layer of the cornea is called the epithelium.

The pupil changes shape to control the amount of light
entering the eye.

The iris is the colored part of the eye. It contains muscles that dilate
(open) or constrict (close) the pupil.

The lens is a clear disc of tissue that changes shape
(accommodates) to help focus light.

The retina lines the inside of the eye. It turns
light into signals that are sent to the brain.

The optic nerve carries signals from the
retina to the brain.