Understanding How Your Eye Works

To decide whether laser vision correction is right for you, it is important to understand how your eye works. The primary purpose of the eye is to focus light. Contact lenses or glasses may be needed to focus rays of light properly.

An eye works very much like a camera. Light enters the eye through the cornea often referred to as the “window of the eye.” The light travels through the pupil and then through the lens. The lens acts by fine-tuning the focus of light onto the retina. The retina turns the light energy into electrical impulses that travel from the eye to the brain where the image is interpreted.

A short description of the various parts of the eye follows and will help you understand the process of vision, why vision may be blurry, and how refractive disorders may be corrected.

CORNEA The cornea is the most anterior surface of the eye and provides most of the focusing power. Small changes in the cornea can have a large effect on how the eye focuses light.

PUPIL The pupil is the black spot or hole in the center of the iris. The pupil acts to regulate the amount of light that enters the eye. In the bright sunlight, it becomes smaller to let in less light. In a dark environment, the pupil expands to allow more light to reach the retina.

IRIS The iris is the colored part of the eye. The muscles of the iris act to control the size of the pupil.

LENS The lens is a normally clear structure located behind the pupil. It acts to fine-tune focusing. By changing shape, the lens allows focusing at far and near. This ability to focus at near (accommodation) gradually worsens with age as the lens gets harder and less supple. Most people notice this in their early 40’s. In people over 60, the lens may become cloudy and interfere with vision. This is called a cataract.

RETINA The retina is a thin layer of tissue that lines the inside wall of the eye. It is very similar to film in a camera in that it functions to capture and transmit images to the brain.

OPTIC NERVE The optic nerve carries the images from the retina to the brain.

SCLERA The sclera is the support layer of the eye. It is the white part of the eye that provides structure and protection for the eye.

VITREOUS The vitreous is the clear gel substance that fills the space between the lens and the retina. Opacities in the vitreous are seen as floaters.