The cornea is the clear, outer layer covering the front
of the eye. It acts as a barrier to protect the eye from foreign objects, helps
with vision by focusing light, and filters ultraviolet rays that enter the eye.
The cornea can usually heal itself after scratches or
minor injuries. However, the cornea and other external eye structures require
medical treatment for more serious injuries, allergies, inflammation,
infections, corneal dystrophies, and a wide range of other conditions.