Overview

Keratitis is an inflammation of the cornea — the clear, dome-shaped tissue on the front of your eye that covers the pupil and iris. Keratitis is sometimes caused by an infection involving bacteria, viruses, fungi or parasites. Noninfectious keratitis can be caused by a minor injury, wearing your contact lenses too long or other noninfectious diseases.

If you have eye redness or other symptoms of keratitis, make an appointment to see your doctor. With prompt attention, mild to moderate cases of keratitis can usually be effectively treated without loss of vision. If left untreated, or if an infection is severe, keratitis can lead to serious complications that may permanently damage your vision.

Symptoms

Signs and symptoms of keratitis include:

  • Eye redness
  • Eye pain
  • Excess tears or other discharge from your eye
  • Difficulty opening your eyelid because of pain or irritation
  • Blurred vision
  • Decreased vision
  • Sensitivity to light (photophobia)
  • A feeling that something is in your eye

When to see a doctor

If you notice any of the signs or symptoms of keratitis, make an appointment to see your doctor right away. Delays in diagnosis and treatment of keratitis can lead to serious complications, including vision loss.

Causes

Causes of keratitis include:

  • Injury. If an object scratches the surface of one of your corneas or penetrates a cornea, keratitis without an infection may result. In addition, an injury may allow bacteria or fungi to gain access to the cornea through the damaged surface, causing infectious keratitis.
  • Contaminated contact lenses. Bacteria, fungi or parasites — particularly the microscopic parasite acanthamoeba — may inhabit the surface of a contact lens or contact lens carrying case. The cornea may become contaminated when the lens is in your eye, resulting in infectious keratitis.
  • Viruses. Viruses such as the herpes viruses (herpes simplex and herpes zoster) and the virus that causes chlamydia may cause keratitis.
  • Contaminated water. Chemicals in water such as those used in swimming pools may irritate the cornea and weaken the delicate surface tissue of the cornea (corneal epithelium), resulting in a chemical keratitis. This is usually short-lived and may last only minutes to hours.

    Bacteria, fungi and parasites in water — particularly in oceans, rivers, lakes and hot tubs — can enter your eyes when you're swimming or bathing and result in keratitis. If you're exposed to these microorganisms, a healthy cornea is unlikely to become infected. But if you've experienced some previous breakdown of the corneal epithelium, such as from wearing a contact lens too long, your cornea may be vulnerable to infection.

Risk factors

Factors that may increase your risk of keratitis include:

  • Contact lenses. Wearing contact lenses increases your risk of both infectious and noninfectious keratitis. The risk typically stems from not disinfecting lenses properly, wearing contact lenses while swimming, wearing them longer than recommended, or using water or homemade solutions to store and clean lenses.

    Keratitis is more common in people who use extended-wear contacts, or wear contacts continuously, than in those who use daily wear contacts and take them out at night.

  • Reduced immunity. If your immune system is weakened due to disease or medications, you're at higher risk of developing keratitis.
  • Warm climate. If you live in a warm, humid climate, your risk of keratitis is increased, particularly if plant material gets into your eyes. Plant material can scratch the corneal epithelium and chemicals from the plant can cause an inflammation, which may then lead to an infection.
  • Corticosteroids. Use of corticosteroid eyedrops to treat an eye disorder can increase your risk of developing infectious keratitis or worsen existing keratitis.
  • Eye injury. If one of your corneas has been damaged from an injury in the past, you may be more vulnerable to developing keratitis.

Complications

Potential complications of keratitis include:

  • Chronic corneal inflammation
  • Chronic or recurrent viral infections of your cornea
  • Open sores on your cornea (corneal ulcers)
  • Corneal swelling and scarring
  • Temporary or permanent reduction in your vision
  • Blindness

Prevention

Caring for your contact lenses

If you wear contact lenses, proper use, cleaning and disinfecting can help prevent keratitis. Follow these tips:

  • Choose daily wear contacts, and take them out before you go to sleep.
  • Wash, rinse and dry your hands thoroughly before handling your contacts.
  • Follow your eye care professional's instructions for taking care of your lenses.
  • Use only sterile products that are made specifically for contact lens care. And use lens care products made for the type of lenses you wear.
  • Gently rub the lenses during cleaning to enhance the cleaning performance of the contact lens solutions. Avoid rough handling that might cause your lenses to become scratched.
  • Replace your contact lenses as recommended.
  • Replace your contact lens case every three to six months.
  • Discard the solution in the contact lens case each time you disinfect your lenses. Don't "top off" the old solution that's already in the case.
  • Don't wear contact lenses when you go swimming.

Preventing viral outbreaks

Some forms of viral keratitis, such as keratitis caused by the herpes virus, can't be completely eliminated. But the following steps may control viral keratitis recurrences:

  • If you have a cold sore or a herpes blister, avoid touching your eyes, your eyelids and the skin around your eyes unless you've thoroughly washed your hands.
  • Don't use corticosteroid eyedrops unless they have been prescribed by a specialist knowledgeable about viral keratitis and the need for careful monitoring. Corticosteroid drops can increase your risk of developing viral keratitis and, if a viral infection does occur, these drops can make it more severe.
  • If you wear contact lenses and have multiple recurrences of viral keratitis, discontinuing your use of contact lenses may decrease your risk of recurrences. Discuss this option with your eye doctor.
Sept. 10, 2015
References
  1. What is baceterial keratitis? American Academy of Ophthalmology. http://www.geteyesmart.org/eyesmart/diseases/bacterial-keratitis.cfm. Accessed June 28, 2015.
  2. Basics of bacterial keratitis. Centers for Disease Control and Prevention. http://www.cdc.gov/contactlenses/bacterial-keratitis.html. Accessed June 28, 2015.
  3. Jacobs DS. Evaluation of the red eye. http://www.uptodate.com/home. Accessed June 28, 2015.
  4. Bacterial keratitis preferred practice pattern — 2013. American Academy of Ophthalmology. http://www.aao.org/preferred-practice-pattern/bacterial-keratitis-ppp--2013. Accessed June 28, 2015.
  5. DeLoss KS, et al. Complications of contact lenses. http://www.uptodate.com/home. Accessed June 28, 2015.
  6. Yanoff M, et al. Noninfectious keratitis. In: Opthalmology. 4th ed. Philadelphia, Pa.: Saunders Elsevier; 2014. http://www.clinicalkey.com. Accessed June 28, 2015.
  7. Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, Pa.: Saunders Elsevier; 2015. https://www.clinicalkey.com. Accessed June 28, 2015.
  8. Protect your eyes. Centers for Disease Control and Prevention. http://www.cdc.gov/contactlenses/protect-your-eyes.html. Accessed June 28, 2015.
  9. Basics of HSV (Herpes Simplex Virus) Keratitis. Centers for Disease Control and Prevention. http://www.cdc.gov/contactlenses/viral-keratitis.html. Accessed June 28, 2015.
  10. What is herpes keratitis? American Academy of Ophthalmology. http://www.geteyesmart.org/eyesmart/diseases/herpes-keratitis.cfm. Accessed Aug. 1, 2012.
  11. Robertson DM (expert opinion). Mayo Clinic, Rochester, Minn. July 10, 2015.