What is keratitis?

What is keratitis?

Keratitis is an eye inflammation which is painful. It may be due to an illness or an injury. There are a number of different types of keratitis and different treatments are required for each type.

The eye is extremely sensitive, and it protects itself from damage by several ways. The eyelid covers the eye and it is protected by tears and fluid against infection. The cornea is the eye’s outermost layer which provides a barrier to dirt, germs and diseases.

Since the cornea is one of the first defense line, it can become irritated and inflamed. This is known as keratitis.

Keratitis and the eye

Keratitis is a painful inflammation of the cornea and can have various causes.
Keratitis is a painful inflammation of the cornea and can have various causes.

Keratitis is a corneal-influencing disease, the translucent outer layer at the front of the eye. The cornea helps the eye focus so it can clearly see things.

Keratitis causes inflammation on the cornea. That can be very painful, cause vision problems , and make the eye more light sensitive.

There is not one single cause for keratitis. There are a variety of different types of keratitis, and different treatments are needed for each type.

Causes and risk factors

Keratitis typically develops when something, like an illness or injury, has irritated the eye. Such risk factors cause keratitis more likely to develop.

Wearing contact lenses is a risk, particularly if one wears them overnight. If contact lenses or a contact lens case are not kept clean, the risk of having keratitis is increased.

A person who’s had an eye disease or injury recently may mean they ‘re more likely to develop the condition. People with the herpes simplex virus may develop viral keratitis.

Keratitis can be due to the drying out of the eyes. An eyelid or tear duct problem can mean a person’s eye isn’t as moist as it needs to be.

Fungal keratitis occurs when the eye is injured by a part of a tree or plant, such as a twig, so those who work with plants are at greater risk.

Exposing the eyes to water — like swimming or in a hot tub — poses a high risk of keratitis.

A person should always clean them contact lenses with a solution to the contact lens, not wash them in water.


A lady puting finger in her eyes
Keeping contact lenses and lens cases clean will help reduce the risk of developing keratitis.

There are two main types of keratitis: infectious and noninfectious. Other forms of the condition exist within these two categories.

Noninfectious causes of keratitis include:

  • wearing contact lenses for too long
  • the eye drying out, sometimes if the eye does not produce enough tears
  • an allergy, for example to cosmetics or pollution
  • something in the eye that should not be there
  • injury to the cornea
  • exposure to intense sunlight, for example from water or snow
  • vitamin A deficiency

Infectious types of keratitis include:

  • bacterial, usually from unclean contact lenses
  • fungal, most often from an eye injury by a tree branch or plant
  • viral, from infection with the herpes simplex virus or herpes zoster virus
  • parasitic, caused by a tiny organism often found in lakes and rivers

The best treatment for keratitis depends on what kind of condition someone has.


Pain in the eye is the hallmark of keratitis. Since the cornea is the part of the eye which helps to focus sight, vision can become blurred.

Someone may also feel they have something in their eyes, even if they don’t, and their eyes may water more than normal. The eye may appear red too, and some discharge may occur.

A person suffering from keratitis may be sensitive to light, known as photophobia. They may dislike looking in the house toward a light, having a bright light on, or being out in strong sunlight.


Keratitis can be serious and may cause vision loss or blindness if left untreated. If diagnosed early enough, the condition is normally treatable.

Complications can include permanent scarring, ulcers on the cornea, or less commonly glaucoma. This is a disorder in which pressure inside the eye can cause vision problems.

If a person has keratitis symptoms, they should see a doctor or an eye doctor.


An eye doctor will examine the eye and ask questions about what the keratitis may have caused.

A doctor may diagnose bacterial or fungal keratitis by taking a small scrap from the cornea to send it to a research lab.

Viral keratitis will not require laboratory testing but a doctor may ask for details about the medical history of a person.

Parasitic keratitis may require a more detailed eye exam so the doctor can see the parasite causing the condition.


A lady using eye drop
Antibacterial eye drops may be prescribed for mild bacterial keratitis.

If a person has keratitis and wears contact lenses, they should remove them as soon as any signs of infection or discomfort develop. Contact lenses are not to be used again until the condition is gone.

A doctor can consider using antibacterial eye drops if a person has mild bacterial keratitis.

In more serious cases the patient can need antibiotics. If the keratitis is particularly severe, steroid eye drops can reduce inflammation.

People at home can apply eye drops, and they will need to be used regularly. As the condition improves, individuals can use the medication less often.

People with fungal keratitis will need to take some months of antifungal medication. If this does not resolve the condition, then in extreme cases surgery may be necessary.

Treatment of viral keratitis is done with eye drops or antiviral medication. Since there is no cure for herpes simplex virus that can cause viral keratitis, this condition can again arise.

Parasitic keratitis is the hardest type to treat and requires both urgent medical treatment and surgery.

Somebody should see an eye doctor while on treatment if:

  • the condition is not improving with the use of eye drops
  • their sight becomes blurred
  • the eye becomes more painful, or redder
  • a white spot on the cornea grows in size


Apart from viral keratitis, most people can avoid other forms of the condition by following good contact lens hygiene.

People can help to prevent keratitis by:

  • following the advice of their eye doctor about how to wear, replace, store, and clean contact lenses
  • washing and drying hands with soap and water before touching the eyes or contact lenses
  • avoiding sleeping in contact lenses
  • keeping water away from contact lenses, such as when showering or swimming
  • cleaning contact lenses with contact lens solution
  • visiting an eye doctor regularly, and contacting them with any symptoms that give concern

Keratitis may affect those not wearing contact lenses. Protecting the eyes from damage that can cause the condition, is important.

Steps to protect the eyes include:

  • wearing protective eyewear if working with plants or trees
  • wearing sunglasses when exposed to bright sunlight
  • being aware of anything that can cause an allergy, and avoiding them if possible
  • eating a diet that includes vitamin A, which can be found in milk and eggs

Minimizing the risk of viral keratitis may also be possible. People should be careful not to touch the eyes or the area around them, and use only eye drops that a doctor has prescribed.


Keratitis is treatable, but as soon as the eye is inflamed it is necessary to avoid wearing contact lenses.

A person should seek medical advice to identify the cause of the condition, since treatment may vary depending on the root of the issue.

Those wearing contact lenses are most at risk to become susceptible to infection. In most cases keratitis should be avoided following advice on cleaning and storing contact lenses.