Cornea

The National Eye Institute (NEI) describes the cornea as the clear outer layer at the front of the eye. MedlinePlus calls it the outermost layer of the eye and says it is clear and shaped like a dome. If a person wears contact lenses, they float on top of the corneas.

According to the NEI, the cornea helps the eye to focus light so a person can see clearly. MedlinePlus adds that the cornea helps to shield the rest of the eye from germs, dust, and other harmful matter.

Keratitis is inflammation (redness and swelling) of the cornea, and the NEI says infections related to contact lenses are its most common cause. Corneal dystrophies cause cloudy vision when material builds up on the cornea, and the NEI says these diseases usually run in families. Small corneal abrasions (scratches) usually heal on their own.

The NEI says to go to the eye doctor or the emergency room for intense eye pain, a change in vision, blurry vision, very red, watery eyes, or an object stuck in the eye. Emergency signs need urgent care (call 911 in the U.S.).

Córnea is the word used by MedlinePlus en español and by the National Eye Institute's Spanish page, and it is feminine: la córnea. The Spanish dictionary lists it under the adjective córneo, a (of horn, or of a consistency like it) as a feminine anatomy noun: a hard, transparent membrane at the front of the eyeball, through which the iris is seen. The same entry records córnea transparente with the meaning córnea, and córnea opaca with the meaning esclerótica.

MedlinePlus en español describes the cornea as la capa externa del ojo, transparente and shaped like una cúpula; the NEI's Spanish page says la capa exterior transparente en la parte delantera del ojo. Related words on the NEI page are queratitis (keratitis), distrofias corneales (corneal dystrophies) and abrasiones or rayaduras (scratches). MedlinePlus en español uses lentes de contacto for contact lenses and trasplante for transplant.