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Vision 101


How Does Your Eye Work?

The human eye works in a manner similar to a camera. Light passes through the cornea and the lens, which focus the light onto the retina. The retina, which can be compared to the film in a camera, contains photosensitive cells that translate the light into an electrical charge, rather like a negative. The charges then pass through the optic nerve to the brain, where they are turned into the images we see.

 

The Anatomy of the Eye:

  • THE ANTERIOR CHAMBER is the portion of the eye located in front of the iris.
  • THE POSTERIOR CHAMBER is the portion of the eye located behind the iris.
  • THE CORNEA is the outer “window” of the eye. It is the primary focusing element of the eye. The outer layer of the cornea is known as the epithelium, which protects the eye. The epithelium is composed of transparent cells which regenerate quickly.
  • THE AQUEOUS HUMOR is a clear, fluid substance that circulates througout the front part of the eye behind the cornea. It maintains a constant pressure inside of the eye.
  • THE IRIS is the colored part of the eye. It assists the eye in adapting to changing light conditions by dilating or constricting the pupil to allow more or less light to pass through the eye.
  • THE LENS focuses light that passes through the eye. The lens can change its shape to focus on near, intermediate and distant objects.
  • THE CILIARY BODY is the structure which secretes the aqueous humor within the eye. The ciliary body also contains the ciliary muscle, which is responsible for changing the shape of the lens.
  • THE ZONULES are fibers which suspend the lens inside of the eye.
  • THE SCLERA is the white part of the eye. It is composed of strong tissues that protect the inner structure of the eye.
  • THE RETINA is a thin, light-sensitive tissue lining the back of the eye. Here, the retina’s photoreceptor cells translate light into electrical pulses and send them to the brain, where they become images.
  • THE MACULA is the center portion of the retina. It contains a high concentration of photoreceptor cells which convert light into nerve signals. Due to this high concentration of photoreceptor cells, the macula is responsible for the sharpness of our vision and our ability to see fine details.
  • THE OPTIC NERVE carries visual information from the eye to the brain.
  • THE CHOROID is a layer of blood vessels behind the retina. The choroid supplies oxygen and nutrients to the outer layer of the retina.
  • THE VITREOUS HUMOR is a gel substance which fills the posterior chamber of the eye.