The Amazing Cornea: The Most Important Part of The Eye
The cornea is the superhero of the eye. It’s responsible for about 75 percent of the eye’s focusing power. It works together with the eyelid, eye socket, tears and sclera—the white part of the eyes—to shield the rest of the eye from foreign particles like dirt and germs.1
The cornea also filters out some of the sun’s harmful ultraviolet (UV) light. (But not all of it, so don’t forget your sunglasses!)
That’s why a healthy cornea is crucial to healthy vision.
How Does the Cornea Work?
The cornea is the dome-shaped, transparent outermost layer of the eye that focuses light on the retina to ensure clear vision.
The cornea and lens focus light on the retina, which is the light-sensitive tissue at the back of the eye. When light strikes the cornea, it bends—or refracts—the light onto the lens. The lens redirects that light onto the retina. The retina converts the light into electrical signals that are sent to the optic nerve and then to the brain. The brain then interprets them as images.
If the cornea is damaged by disease, infection, or an injury, the resulting scars might block or distort light as it enters your eye, causing blurry vision.1
Typical Problems of The Cornea 1
Numerous conditions can affect the cornea. Three of the most common problems are:
The cornea will usually heal itself if it incurs minor injuries such as surface scratches. But more severe injuries can cause scarring, resulting in impaired vision. Symptoms include pain, light sensitivity, redness, reduced or blurry vision, headache, and nausea. If you think you may have suffered a corneal abrasion, seek medical attention right away.
Dry eyes are caused by the lack of sufficient lubrication and moisture on the surface of the eye. Symptoms include constant eye irritation and an inflammation of the front surface of the eye, which can lead to damage of the cornea. Dry eyes are very common and a major reason for visits to the eye doctor.
Keratitis is an inflammation of the cornea. Noninfectious keratitis can be caused by a minor injury, or from wearing contact lenses too long. Infectious keratitis is caused by bacteria, viruses, fungi or parasites. It is often associated with contact lens wear, most notably improper cleaning or overuse of old contact lenses.1
Keeping Your Corneas Healthy
Here are three important things you can do to protect your cornea:2
Schedule regular dilated eye exams to detect eye conditions and diseases early.
Wear protective eyewear. Sunglasses, safety glasses and goggles, safety shields, and eye guards are your eyes best friends at work or play.
Clean your hands and contact lenses—properly. Avoid infection by washing your hands thoroughly before putting in or taking out your contact lenses and by disinfecting and replacing contact lenses as instructed.
Considering all the cornea does, it’s well worth the time and effort it takes to protect this amazing and indispensable part of your eye.