Cornea

Understanding the Cornea

Prior to learning about the services, we offer to treat and repair cornea conditions it is a good idea to familiarize yourself with the cornea part of the eye. The information below details what happens in this outermost layer of the eye and the common cornea diseases.

The cornea is the eye’s outermost layer. It is the clear, dome-shaped surface that covers the front of the eye and plays an important part in the eye’s visual acuity. Corneal tissue consists of five basic layers: epithelium, Bowman’s layer, stroma, Descemet’s membrane and endothelium. Although the cornea is clear, it contains 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 that fill the chamber behind it.

The cornea, one of the protective layers of the eye, serves two functions:

  • First, along with the eyelid, eye socket, and sclera (white part of the eye), and the tear film, the cornea shields the eye from dust, germs, and other harmful matter.
  • Second, as the eye’s outermost lens, it is the entry point for light into the eye. When light strikes the cornea, it bends, or refracts, the incoming light onto the lens. The lens further refocuses the light onto the retina, a layer of light-sensing cells lining the back of the eye.

To see clearly, the cornea and lens must focus the light rays precisely on the retina. This refractive process is similar to the way a camera takes a picture. The cornea and lens in the eye act as a camera’s lens would. The retina approximates the film. If the cornea is unable to focus the light properly, then the retina receives a blurry image.

Diseases of the Cornea

Keratoconus can cause considerable distortion of vision including double vision, streaking and sensitivity to light. It is a degenerative condition of the cornea that causes thinning and shifting from a normal gradual curve to more conical shape.

Corneal dystrophy is a disorder that causes a layer of the cornea to cloud over and impair visual clarity. It is caused by a group of genetic disorders that generate abnormal material that accumulates in the cornea.

This condition is one in which the cornea becomes inflamed. It can be moderately painful, itchy and sometimes involves impaired vision.

Caused by the type 1 herpes simplex virus, this condition is a common, recurring viral infection distressing the eyes. This type of condition can cause inflammation and scarring of the cornea that sometimes is referred to as a cold sore on the eye.

This condition is a progressive disease affecting the cornea that reduces the number of endothelial cells that make up the inner layer of the cornea. These cells stop processing water and fluid starts to build up and begin to cloud vision.

Cornea Procedures Offered


What does the cornea do? 

The cornea shields the eye from dust, germs, and other harmful matter. It works together to protect the eye along with the eyelid, eye socket, sclera, and tear film.

As the eye’s outermost lens, it is also the entry point for light into the eye. When light enters the cornea, it bends or refracts the incoming light onto the lens and refocuses light onto the retina. 

The retina contains a layer of light-sensing cells lining the back of the eye. To see clearly, the cornea and lens need to focus light rays precisely on the retina.  


How does the cornea work?

Besides allowing the light to enter the eye, the cornea has another critical function. It provides up to 75 percent of the focusing power of the eye. 

The rest of your eye’s focusing power is provided by the lens, located directly behind the pupil. If someone is nearsighted, farsighted, or has astigmatism, the cornea’s curvature is not optimal. 

However, presbyopia, or farsightedness due to aging, is due to a change in the lens behind the pupil. When this happens, it’s because the lens loses its flexibility. 

Cornea Doctors

Dr. Heath L. Lemley
Heath L. Lemley, MD

 

*As with any surgical procedure there are risks along with benefits. It is important to discuss your surgical procedure with your surgeon to fully understand the risks and benefits.

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