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What is the cornea?
The cornea is the eye’s outermost layer. It is the clear, dome-shaped surface that covers the front of the eye.
Structure of the Cornea

Structures of the eye and layers of the cornea.Although the cornea is clear and seems to lack substance, it is actually a highly organized group of cells and proteins. Unlike most tissues in the body, the cornea contains no blood vessels to nourish or protect it against infection. Instead, the cornea receives its nourishment from the tears and aqueous humor (a fluid in the anterior portion of the eye) that fills the chamber behind it. The cornea must remain transparent to refract light properly, and the presence of even the tiniest blood vessels can interfere with this process. To see well, all layers of the cornea must be free of any cloudy or opaque areas.

The corneal tissue is arranged in five basic layers, each having an important function.

What conditions may cause the need for a corneal transplant?

  • Corneal failure after another eye surgery, such as cataract surgery
  • Keratoconus, a steep curving of the cornea
  • Hereditary corneal failure, such as Fuchs’ dystrophy
  • Scarring after infections, especially after herpes
  • Rejection after a first corneal transplant
  • Scarring after injury

Information provided by the National Eye Institute & American Academy of Ophthalmology

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