Keratitis is an inflammatory condition that affects the cornea of your eye. The cornea is the clear part that covers both the iris and the pupil. Keratitis can be caused by an infection or injury to the eye.

Keratitis is a common condition. People who wear contact lenses may experience keratitis more frequently than people who don’t wear contacts. In either case, you can take steps to help prevent this condition. If you do develop keratitis, see your doctor right away.

Symptoms of keratitis include:

  • red eyes
  • pain and irritation in the affected eye
  • vision changes, such as blurriness or inability to see
  • sensitivity to light
  • inability to open your eye
  • eye discharge
  • excessive tearing

Without treatment, keratitis symptoms will progress and get worse. When symptoms appear can depend on the type of keratitis. For example, bacterial keratitis symptoms can appear right away.

Learn more about eye care »

There are two main types of keratitis, depending on what causes it. Keratitis may be classified as either infectious or noninfectious.

Infectious keratitis

Infectious keratitis is caused by one of the following:

Bacteria: Pseudomonas aeruginosa and Staphylococcus aureus are the two most common types of bacteria that cause bacterial keratitis.It mostly develops in people who use contacts improperly.=

Fungi: Fungal keratitis is caused by Aspergillus, Candida, or Fusarium. As with bacterial keratitis, fungal keratitis is most likely to affect those who wear contact lenses. However, it’s also possible to be exposed to these fungi outdoors

Parasites: An organism called Acanthamoeba has become more common in the United States in those wear contact lenses. The parasite lives outdoors and may be picked up by swimming in a lake, walking in a wooded area, or getting infected water on your contact lenses. This type of infection is called Acanthamoeba keratitis.

Viruses: Viral keratitis is primarily caused by the herpes simplex virus, which progresses from conjunctivitis to keratitis.

Learn more about conjunctivitis »

Noninfectious keratitis

Possible noninfectious causes of keratitis include:

  • eye injury, such as a scratch
  • wearing your contacts too long
  • using extended-wear contacts
  • wearing your contacts while swimming
  • living in a warm climate, which increases the risk of plant materials damaging your cornea
  • a weakened immune system
  • exposure to intense sunlight, called photo keratitis

Read more: Serious eye problems caused by misuse of contact lenses »

Keratitis may be transmitted through an infection. This can happen if you come into contact with an infectious substance and then touch your eyes. It can also occur if you get sick and then the infection spreads to your eyes.

In some cases, you can even transmit keratitis to yourself. For example, if you have an open sore from herpes, touching it before touching the eye area can lead to this condition.

Noninfectious keratitis isn’t contagious. These cases only become contagious if an infection develops.

Any suspected symptoms of keratitis should be looked at right away. Your doctor can help make a diagnosis so that you can receive treatments before any complications arise.

To diagnose keratitis, your doctor will first talk to you about the history of your symptoms and then look at your eyes. If your eye is sealed shut from an infection, they will help you open it so they can conduct a full examination of the cornea.

A slit lamp or penlight may be used during the exam. A slit lamp works by magnifying the structures within your eye so your doctor can get a closer look at any damage being caused by keratitis. A penlight is used for checking your pupil to look for any unusual changes. A stain may be applied to the eye surface to help your doctor look for any other changes.

To rule out an infection, your doctor may request lab testing. They will collect either a corneal or tear sample to identify the exact cause of the keratitis.

Your doctor may also test your vision with an eye chart.

How your keratitis is treated depends on what is causing it. If you have an infection, you will need to take prescription medications. Your doctor may prescribe eye drops, oral medications, or both. These include:

  • antibiotics for bacterial infections
  • biocides for parasitic infections
  • antifungals for fungal infections
  • antivirals for viral infections

Not all forms of keratitis infections respond to medications in the same way. Acanthamoeba keratitis can sometimes be antibiotic-resistant, so your doctor may need to look at your eyes again if the infection doesn’t clear up. Also, antiviral medications may not fully eliminate the virus that caused your keratitis; you’ll need to be on the lookout for recurring infections as a result.

Noninfectious keratitis doesn’t need medication. You’ll only need a prescription if your condition worsens and develops into an infection. An eye patch can help protect the affected area and encourage the healing process.

When treated promptly, you will likely recover from keratitis. However, complications can arise if it’s left untreated. Untreated keratitis can lead to permanent vision damage.

Other possible complications include:

  • corneal scars
  • recurring eye infections
  • chronic (long-term) inflammation
  • sores in the cornea, known as corneal ulcers

In severe cases, you may need a procedure known as a cornea transplant. Your doctor will likely recommend this surgery if keratitis causes vision damage or blindness.

While keratitis can happen to anyone, there are steps you can take to help prevent its occurrence. This is especially true if you wear contacts. You can:

  • make sure you don’t go to bed with your contacts in
  • remove contacts before swimming
  • only handle your contacts with clean hands
  • use the right types of cleaning solution, never water or diluted solutions
  • replace your contacts regularly, as recommended by your doctor

Preventing viral infections can also help decrease your risk for keratitis. Make sure you wash your hands thoroughly before touching your eyes, especially if you think you’ve been exposed to a virus.

Q:

What’s the difference between keratitis and conjunctivitis?

A:

Conjunctivitis is infection or inflammation of the conjunctiva, which covers the white part of the eye and lines the inside of the eyelids as well. Conjunctivitis can be caused by multiple things. Viruses are the most common cause, though it’s also caused by bacteria and chemicals. Keratitis is inflammation of the cornea, which is the clear covering of the eye. As mentioned above, this can be caused by different things including viruses, fungi, and parasites.

Suzanne Falck, MDAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.