The cornea is the clear window that covers the front of the eye, like the crystal on a watch. If this tissue becomes cloudy, it can cause your vision to become blurry. Light first enters the eye through the cornea, which focuses the light onto the lens. The lens fine tunes the focus as it passes the light image on to the retina where it is converted to electrical impulses and sent to the brain.
The cornea must remain clear to allow light to pass through so your vision will be clear and so the light will be focused correctly. The cornea provides between 65 and 75 percent of the focusing power of the eye. A variety of disorders called corneal dystrophies can affect the cornea by causing a build-up of cloudy material. There are over 20 different dystrophies that can cause some part of the cornea to become cloudy. These are some of the traits the corneal dystrophies have in common:
• Usually inherited
• Can occur in otherwise healthy men or women
• Both eyes are affected equally
• Gradually get worse over time
• Usually begin in one layer of the cornea and later spread into some or all of the other four layers
• Are not caused by factors such as diet or injury to the eye
• Do not usually affect other parts of the body
• Are not usually related to diseases affecting other parts of the body
Corneal dystrophies have widely varying symptoms. Some dystrophies cause severe loss of vision, while others are not noticed unless they are spotted during a routine eye exam. Some dystrophies can cause pain in the eye without causing a loss of vision.
Another condition that can cause clouding of the cornea is a deficiency of Vitamin A and protein in the diet. This condition, which is called karatomalacia, can cause the cornea and the sclera (the white part of the eye) to become dry. This can lead to ulcers and bacterial infections on the surface of the eye. It can also affect the tear glands, decreasing the amount of tears that are produced.
Another cause of a cloudy cornea is guttata or guttae, which means droplets. Very small, clear bumps can appear on the inside back surface of the cornea.