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Interstitial Keratitis

Last updated Oct. 12, 2018

Approved by: Maulik P. Purohit MD, MPH

Interstitial Keratitis is the inflammation the tissue of the cornea, which is the dome-shaped clear cover in the front of the eye.

What are the other Names for this Condition? (Also known as/Synonyms)

  • Corneal Inflammation (Interstitial Keratitis)

What is Interstitial Keratitis? (Definition/Background Information)

  • Interstitial Keratitis is the inflammation the tissue of the cornea, which is the dome-shaped clear cover in the front of the eye. The inflammation of the cornea causes the blood vessels to grow disrupting the vision through the cornea
  • Interstitial Keratitis is a common cause of blindness in the world. It can be caused by exposure to bacteria, viruses, fungi, or parasites. However, a bacterial infection is the most common cause. Eye injuries or infected contact lenses are the main risk factors for Interstitial Keratitis
  • The common signs and symptoms of Interstitial Keratitis may include eye pain, redness, and discharge from the eye. If left untreated, the condition can result in a vision loss
  • Interstitial Keratitis is often treated with corticosteroid drops or oral medications. The prognosis with early diagnosis and treatment is good

There are different types of keratitis, which include:

  • Amoebic Keratitis: It is often seen in those who wear contact lenses and is caused by Acanthamoeba, a free-living amoeba
  • Fungal Keratitis caused by a fungal infection
  • Viral Keratitis that is often caused by herpes simplex virus
  • Photokeratitis: It occurs because of exposure to ultraviolet radiation

Who gets Interstitial Keratitis? (Age and Sex Distribution)

  • Interstitial Keratitis is the most common cause of blindness the world over
  • The condition is not limited to age or sex; commonly, any individual who is exposed to an infection may contract the condition
  • All racial and ethnic groups are affected

What are the Risk Factors for Interstitial Keratitis? (Predisposing Factors)

Risk factors for Interstitial Keratitis include:

  • Individuals who use contact lenses are more at risk for Interstitial Keratitis, if the contact lenses are worn for extensive periods and/or if they are not cared for and cleaned properly
  • Weakened immune systems from disease that can lead to infections
  • The use of corticosteroid eye drops can sometimes increase the risk
  • Injury to the eye, specifically to the cornea
  • Being exposed to bacteria, fungi, and parasites such as Acanthamoeba that can be found in water
  • A previous or existing damage to the cornea increases the risk

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Interstitial Keratitis? (Etiology)

The following are the possible causes of Interstitial Keratitis:

  • Bacterial infections, such as syphilis, are the most common cause of Interstitial Keratitis
  • Bacterial infections can also involve Staphylococcus aureus and Pseudomonas aeruginosa (in individuals who wear contact lenses)
  • Injury to the eye can lead to infection, because bacteria can reach the cornea via the injured or scratched surface
  • Use of contact lenses that are contaminated by bacteria, fungi, or other parasites; improper use of contact lenses
  • Other causes, although much less common than syphilis, include:
    • Leprosy (chronic bacterial infection)
    • Lyme disease (bacterial infection from ticks)
    • Tuberculosis (bacterial infection in the lungs)
    • Mycosis fungoides
    • Heavy metal toxicity
    • Presence of Cogan syndrome
  • The herpes simplex and herpes zoster viruses can also cause corneal inflammation
  • Viruses such as Epstein-Barr virus (EBV), measles, mumps
  • Exposure to contaminated waters containing chemicals can weaken tissue in the cornea
  • Autoimmune diseases (such as rheumatoid arthritis and sarcoidosis)
  • Weakened immunity caused by diabetes, alcoholism, or a lack of healthy nutrition

What are the Signs and Symptoms of Interstitial Keratitis?

The signs and symptoms of Interstitial Keratitis may include:

  • Eye pain
  • Redness in the eye
  • Excessive flow of tears from the eye
  • Light sensitivity
  • Discharge from the eye
  • Poor vision
  • Sensation that there is a foreign object in the eye
  • Restricted eyelid movement

How is Interstitial Keratitis Diagnosed?

Interstitial Keratitis is generally diagnosed using the following methods:

  • Physical examination and medical history assessment: The medical history could include evaluating the following:
    • Previous infections
    • Medication use
    • Insect bites
    • Trauma to the eye
    • Contact lens usage
    • Travel history
  • A general eye exam is used to assess vision and clarity of sight. A penlight exam may be used to examine the reaction of the eye to light
  • Interstitial Keratitis can be further diagnosed through a slit-lamp examination:
    • This examination looks specifically at the front of the eye and the cornea
    • A low-power microscope is used to focus a thin beam of light to examine the cornea
  • Ultrasound analysis of corneal thickness (ultrasound tachymetry)
  • Measurement of intraocular pressure
  • Culture of corneal swabs can be helpful in detecting the cause of infections, if any
  • If syphilis is suspected, then blood tests for syphilis
  • If viral infection is suspected, then testing blood for viral antibodies
  • Tear samples or corneal cell samples can be observed in a lab to confirm the inflammation, and whether it is due to Interstitial Keratitis

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Interstitial Keratitis?

The possible complications of Interstitial Keratitis include:

  • Corneal transplants that are performed for treatment of Interstitial Keratitis may not always be successful
  • Corneal ulcers or sores may develop; the cornea can swell and scar as a result
  • Poor or reduced vision may become permanent
  • If left untreated, Interstitial Keratitis can lead to blindness

How is Interstitial Keratitis Treated?

  • The treatment of Interstitial Keratitis depends on the underlying cause. If the cause is due to an infection, then the first step is to treat the infection
  • If the cause is due to an immune-related condition, then controlling the underlying immune-related condition is crucial
  • The treatment also involves changing the type of contact lens being used (if Interstitial Keratitis is caused by the use of contact lenses)
  • Corticosteroid drops can be used as a treatment to lessen scarring. This will also prevent the clouding of the cornea which affects vision
  • If the inflammation has ended and the cornea is scarred with irregular blood vessels, a corneal transplant is necessary to repair vision
  • Close follow-up and regular monitor of the condition is necessary

How can Interstitial Keratitis be Prevented?

Preventative measures to stop the spread of Interstitial Keratitis may include:

  • Since Interstitial Keratitis is due to an infection, avoiding individuals who are infected (especially with syphilis) is important to avoid infection
  • Proper cleaning and use of contact use is important, especially if the contacts are used for extended amounts of time:
    • Daily disposable contact lenses can help prevent constant infection
    • Contacts should be cleaned properly with contact lens solution
    • Contacts should be replaced as instructed by a healthcare provider (or as marked on the label)

What is the Prognosis of Interstitial Keratitis? (Outcomes/Resolutions)

When detected and treated early, the progression of Interstitial Keratitis can be controlled; the vision and clarity of the cornea can also be restored.

  • Sometimes, only the uppermost corneal layers are affected and the infection is superficial. In such cases, scars usually do not form after Interstitial Keratitis has healed
  • Interstitial Keratitis that is deep enough in the cornea will generally leave a scar and surgery may be necessary
  • The best way to avoid infection is to use proper cleaning techniques for contact lenses and to keep away from infected individuals
  • With early detection of Interstitial Keratitis and determination of the underlying cause, it results in a very good prognosis in a majority of individuals

Additional and Relevant Useful Information for Interstitial Keratitis:

The best way to prevent the spread of infection and treat symptoms of Interstitial Keratitis is to check with a medical professional immediately, if any of the symptoms related to the inflammation occur. Early diagnosis is necessary to preserve the cornea.

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Aug. 2, 2016
Last updated: Oct. 12, 2018