Basics of Bacterial Keratitis

What is bacterial keratitis?

In the United States, bacterial keratitis is most common among people who wear contact lenses.¹

Read CDC’s Protect Your Eyes page to learn more about healthy contact lens wear and care habits.

Bacterial keratitis is an infection of the cornea (the clear dome covering the colored part of the eye) that is caused by bacteria. It can affect contact lens wearers, and also sometimes people who do not wear contact lenses. Types of bacteria that commonly cause bacterial keratitis include:

• Pseudomonas aeruginosa
• Staphylococcus aureus

What are the symptoms of bacterial keratitis?

Symptoms of bacterial keratitis include:

• Eye pain
• Eye redness
• Blurred vision
• Sensitivity to light
• Excessive tearing
• Eye discharge

If you experience any of these symptoms, remove your contact lenses (if you wear them) and call your eye doctor right away. If left untreated, bacterial keratitis can result in vision loss or blindness.

Where are these bacteria found?

Bacteria are common in nature and found in the environment and on the human body. Pseudomonas bacteria can be found in soil and water. Staphylococcus aureus bacteria normally live on human skin and on the protective lining inside the body called the mucous membrane (for example, the lining of the eyes, nose, or mouth). Bacterial keratitis cannot be spread from person to person.

What puts people at risk for bacterial keratitis?

Risks for developing bacterial keratitis include:^{1, 2}

• Wearing contact lenses, especially:
  • Overnight wear^3-6
  • Temporary reshaping of the cornea (to correct nearsightedness) by wearing a rigid contact lens overnight, otherwise known as orthokeratology (Ortho-K)^6-9
  • Not disinfecting contact lenses well
  • Not cleaning contact lens cases
  • Storing or rinsing contact lenses in water
  • Using visibly contaminated lens solution
  • “Topping off” lens solution rather than discarding used solution and replacing
  • Sharing colored or decorative contact lenses
• Recent eye injury
• Eye disease
• Weakened immune system
• Problems with the eyelids or tearing

How is bacterial keratitis diagnosed?

When you first notice unusual eye irritation, it is critical that you remove your contact lenses and don’t wear them again until instructed to do so by your eye doctor. Your eye doctor will examine your eye. He or she may take a tiny scraping of your cornea and send a sample to a laboratory to be analyzed.