An Overview of Keratitis

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Keratitis is an eye condition in which the cornea—the clear, round dome covering the eye’s iris and pupil—becomes swollen or inflamed, making the eye red and painful. In some cases, keratitis can affect your vision.

Noninfectious keratitis may develop after a minor injury to the eye, by wearing your contact lenses too long, or by a foreign body entering the eye. Infectious keratitis is caused by bacteria, viruses, fungi, or parasites.

keratitis causes
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If you suddenly develop eye redness or symptoms of keratitis, be sure to see your eye doctor promptly. Most cases of keratitis can be treated without loss of vision. However, a severe infection can lead to serious complications that may permanently damage your vision.


The first symptom of keratitis is usually redness and pain in the eye. Normally only one eye is affected, but in some cases, the condition can affect both eyes.

The following symptoms are often associated with keratitis:

  • Red eyes
  • Eye pain and irritation
  • Swelling around the eye
  • Burning, itchy, or gritty feeling in the eye
  • Vision changes (blurry or vision loss)
  • Light sensitivity
  • Difficulty opening eye
  • Eye discharge
  • Excessive tearing

If you notice any of the signs or symptoms listed above, it’s important to see your healthcare provider right away. Delays in treatment could cause serious vision complications.


Keratitis is classified into two types: infectious or noninfectious. The cause of the keratitis determines its type.


The following conditions may lead to noninfectious keratitis:

  • Wearing contact lenses (especially if a person wears contact lenses overnight. Failing to keep contact lenses or a contact lens case clean greatly increases the chance of developing keratitis)
  • Eye injury including a scratch or a blow to the eye
  • Wearing your contacts for too long
  • Wearing extended-wear contacts
  • Wearing your contacts while swimming in a pool or lake
  • Outdoor plant materials getting into the eyes
  • A weakened immune system
  • Exposure to intense sunlight (photokeratitis)
  • Dry eye syndrome


The following can lead to infectious keratitis:

  • Bacteria: Two types of bacteria that can cause infectious keratitis are Pseudomonas aeruginosa and Staphylococcus aureus. Both of these bacterial infections are usually seen with improper contact lens use.
  • Fungi: Fungal keratitis is also often seen in conjunction with improper use of contact lenses. Fungal keratitis can be caused by Aspergillus, Candida, or Fusarium.
  • Parasites: A particularly dangerous form of infectious keratitis is called Acanthamoeba keratitis. This type of infection is usually acquired while wearing contact lenses while swimming in a lake.
  • Viruses: Viral keratitis is usually caused by the herpes simplex virus. This type progresses from a case of conjunctivitis to infectious keratitis.


If you think you may be experiencing symptoms of keratitis, make an appointment with your healthcare provider as soon as possible. In many cases, treatment can be started before any complications arise, including loss of vision.

Your healthcare provider will examine your eyes and discuss the symptoms you are experiencing. It may be difficult to open your eye if you have an active infection, but your healthcare provider will be able to help you.

A complete eye examination may not be necessary. Your healthcare provider will use a slit lamp to get an excellent view of the inside of your eye. A special stain may be used in order to see any damage that may have already been caused to the internal structures of your eye. A slit lamp can also help your healthcare provider identify irregularities or ulcers of the cornea.

If your healthcare provider suspects an infection, lab testing may be needed. A sample obtained from your eye can help identify what has caused the infection. A vision test may also be performed to make sure vision loss has not occurred. Once a proper diagnosis has been made, your treatment can begin.


Treatment of keratitis depends on the cause of the condition. Noninfectious keratitis, such as a corneal scratch or other injury, may not require any treatment. Your healthcare provider may prescribe an antibiotic or prescription pain medication if you are in significant pain, and in order to speed healing. In some cases, a protective eye patch may be worn to protect the eye during healing.

If dry eye syndrome may be causing your keratitis symptoms, your healthcare provider will perform the Schirmer tear test. A small strip of paper will be inserted into the corner of your eye to measure moisture. If your healthcare provider confirms dry eye syndrome, your treatment will focus on moisturizing your eyes to relieve symptoms. In most cases, moisture is improved by the use of artificial tears and lubricating ointments.

Treatment of infectious keratitis will focus on controlling the underlying cause of the infection.

  • Bacterial keratitis: Your healthcare provider will prescribe antibacterial eye drops for mild cases of bacterial keratitis. Oral antibiotics may be needed for severe cases.
  • Fungal keratitis: Oral antifungal medication and antifungal eye drops will be prescribed.
  • Viral keratitis: Your healthcare provider will try antiviral eye drops and oral antiviral medications. In some cases, the virus may be stubborn and reoccur, requiring more treatment.
  • Acanthamoeba keratitis: Your healthcare provider will be aggressive with this serious condition, as vision loss is a possibility. Antibiotic eye drops will be prescribed.

Some cases of infectious keratitis are resistant to many forms of medication. If your eye is permanently damaged, your healthcare provider may recommend having a corneal transplant.

Coping and Prevention

If your eye suddenly becomes red and inflamed, promptly remove your contact lenses if you wear them. Try not to touch or rub your eyes. Lubricating eye drops can be helpful for easing the symptoms of keratitis.

Many forms of keratitis can be prevented by following good hygiene habits, especially if you wear contact lenses on a daily basis. Be sure to follow your healthcare provider's advice about wearing, cleaning, and storing your contact lenses. Always wash your hands before handling your contacts, and remove them before sleeping or swimming.

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Srinivasan M, Mascarenhas J, Prashanth CN. Distinguishing infective versus noninfective keratitis. Indian J Ophthalmol. 2008;56(3):203-7. doi:10.4103/0301-4738.40358

  2. Austin A, Lietman T, Rose-nussbaumer J. Update on the Management of Infectious Keratitis. Ophthalmology. 2017;124(11):1678-1689. doi:10.1016/j.ophtha.2017.05.012

Additional Reading
  • Austin, Ariana, MS, Tom Lietman, MD and Jennifer Rose-Nussbaumer, MD. Update on the Management of Infectious Keratitis. Ophthalmology, Vol 124 Issue 11, American Academy of Ophthalmology (AAO) Nov 2017. DOI: 10.1016/j.ophtha.2017.05.012.

By Troy Bedinghaus, OD
Troy L. Bedinghaus, OD, board-certified optometric physician, owns Lakewood Family Eye Care in Florida. He is an active member of the American Optometric Association.