The cornea is the eye’s clear, dome-shaped layer on the front of the eye. Normally, a healthy cornea can resist infection very effectively. However, the cornea may be damaged by injury such as a poke in the eye or it may become inflamed through infection. Unlike most tissues, the cornea contains no blood vessels to shield it from infection. A corneal infection, or keratitis, occurs when the cornea is damaged by a foreign object, or from bacteria or fungi (often from a contaminated contact lens). This can cause painful inflammation and can lead to corneal scarring. In the most serious cases, keratitis can cause blindness.
Types of Corneal Infections
The most common type of infectious keratitis is bacterial keratitis. It is often caused by wearing contacts overnight. Although the Food and Drug Administration has approved some extended-wear lenses for 30-day use, this does increase the risk of infection significantly. Sleeping in your contacts makes you much more prone to keratitis, so it is recommended that you remove your contacts every day, clean and rinse them thoroughly, and store them with fresh contact solution. Be sure to talk through the risk with your eye doctor.
Some viruses and fungi can also cause keratitis. Tap water can contain a germ that causes keratitis, and contact lens wearers are more susceptible to this type of keratitis as well. While it may seem logical to store contact lenses in tap water when you have run out of contact lens solution, this choice may cause a severe eye infection.
Not all types of keratitis are infectious. Noninfectious keratitis can result from:
- Eye injury from a scratch or foreign object
- Allergic reaction to deposits on the lenses
- Chemicals, including those in contact lens solution
- Dryness of the eyes
Warning Signs & Symptoms
Symptoms of a corneal infection can include:
- An itchy/burning feeling in your eye
- Painful sensitivity to light
- Decreased vision
- Eye discharge
You may even develop a white spot where the infection is located that is actually visible. If you wear contacts and your eye is red and irritated, you may have infectious keratitis. The deeper the infection, the more painful the symptoms will be. It is important to call your eye doctor immediately if you wear contacts and have any of these symptoms.
Treatment and Procedures
A specialized optical microscope can be used to determine the location, depth and severity of the corneal infection. Sometimes, your eye doctor will culture the infection to identify the type of organism that is causing the keratitis.
Minor infections are usually treated with prescription anti-bacterial drops. More severe infections need stronger antibiotics or anti-fungal treatment to clear up infections, as well as steroid drops for inflammation. Sometimes, corneal infections take multiple treatments to cure and frequent visits to the eye doctor are necessary. If corneal scarring occurs, it can lead to loss of vision and, possibly, blindness. In the case of a corneal scar, a corneal transplant may be required.
Contact lens wearers are at higher risk of corneal infections, so proper contact lens care is important. Avoid sleeping in contact lenses or over-wearing contact lenses. Dispose of soft contacts as directed by your eye doctor. Also use protective eyewear during activities that could accidentally throw particles or other foreign bodies into the eye. Individuals who are very active or play sports should be especially cautious to avoid eye injury that could cause noninfectious keratitis.
Remember that regular comprehensive eye exams are important for good eye health, even if you do not detect any changes or problems in your vision. The best way to keep your eyes free from disease is to schedule comprehensive eye exams every one to two years, according to your eye doctor’s recommendations.