Humans are blessed with eyes that allow excellent colored as well as black and white vision which act as a camera for the brain. Quite often when an individual ages, the lens of the eye can become cloudy impairing vision. Surgery for removal of the cloudy lens corrects this problem and restores vision to normal. Approximately 1.2 million cataract surgeries are performed annually in the United States.

Anatomy and Physiology

• There are two eyes that lie in bony casings within the skull called orbits
  
• Each eye is globular in shape and about one inch in diameter
  
• Light entering the front of the eye passes through the cornea, anterior chamber, iris, lens and vitreous and finally is focused on the retina, the film of the eye. (Figure 1)
  
• The cornea is a curved, highly transparent tissue that separates air from clear fluid in the anterior chamber of the eye, which lies between the cornea and lens
• The lens is a firm gel-like transparent tissue that is almost eight millimeters (one-third inch) in diameter and biconvex in shape, that is, thicker in the center than at the edge. A thin transparent capsule surrounds the lens.
  
• In front of the lens is the iris, a circular pigmented muscle that gives the eye its color. It has a hole in its center, the pupil. The iris acts like the diaphragm of a camera and adjusts the amount of light that enters the eye through the pupil
  
• Light then passes through the vitreous, a clear gel-like material that fills the center of the eye, onto the retina
  
• The retina is the film of the eye. It is a true extension of the brain and is composed of special nerve cells sensitive to light
  
• The optic nerve is formed from these nerve cells and carries the light image entering the eye to the brain
  
• Light entering the eye is focused at two places, the cornea and the lens. Light is primarily bent as it passes the cornea and then fine focused as it passes through the lens
  
  

Figure 1 - Eye Normal