The
cornea is the transparent tissue that covers the front of the
eye. An easy way to locate the cornea is to look at your eye
in the mirror. You will notice a clear surface covering the
iris (the colored part of the eye) and pupil. That clear surface
is the cornea.
What
is the function of the cornea?
Because
the cornea is as smooth and clear as glass, but as strong and
durable as plastic, it helps the eye in two ways:
The
cornea provides a physical barrier that shields the inside
of the eye from germs, dust and other harmful matter. It
shares this protective task with the sclera (the white of
the eye).
The
cornea acts as the eye’s outermost lens. When light
strikes the cornea, it bends or refracts the incoming light
onto the crystalline lens. The lens then focuses the light
onto the retina, the paper-thin tissue at the back of the
eye that begins the translation of light into vision.
What
are some of the problems that may affect the cornea?
The
cornea copes very well with minor injuries or abrasions. If
dirt scratches the cornea, it usually heals before infection
occurs and vision is affected. But if the scratch penetrates
the cornea more deeply, the healing process will take longer,
resulting in greater pain, blurred vision, tearing, redness
and extreme sensitivity to light. These symptoms may require
professional treatment.
Some
of the major problems that affect the cornea are:
A
group of inflammatory and often contagious diseases
of the conjunctiva (the protective membrane that lines
the eyelids and covers exposed areas of the white of
the eye). These diseases can be caused by a bacterial
or viral infection, drug allergy, environmental irritants,
or a contact lens product.
In
most cases, the infection will come and go without the
need for medical care. But for some forms of pink eye,
treatment will be required. Depending on the type of
pink eye that a person develops, treatment often consists
of antibiotics or steroids.
Microbial
Infections (Keratitis):
When
the cornea is damaged, such as after a foreign object
has penetrated the tissue, bacteria or fungi can pass
into the cornea, causing a deep infection and inflammation.
Minor
corneal infections are commonly treated with anti-bacterial
or anti-fungal eye drops. If the problem is more severe,
a person may receive more intensive antibiotic treatment.
Keratoconus:
A
degenerative disease in which the center of the cornea
thins and the cornea becomes conical, rather than spherical,
in shape. This abnormal curvature changes the cornea’s
ability to bend light (refractive power), producing
moderate to severe distortion (astigmatism) and blurring
(near- and farsightedness) of vision.
Ocular
Herpes:
Herpes
of the eye is a recurrent viral infection that affects
an estimated 400,000 people in the U.S. who have herpes.
Ocular herpes produces a painful sore on the surface
of the cornea.
Prompt
treatment with anti-viral drugs often helps stop the
herpes virus from multiplying. However, like other herpetic
infections, herpes of the eye remains a controllable,
but incurable, problem.
