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Definition

Keratitis is an inflammation of the cornea, the transparent membrane that covers the colored part of the eye (iris) and pupil of the eye.

Description

There are many types and causes of keratitis. Keratitis occurs in both children and adults. Organisms cannot generally invade an intact, healthy cornea. However, certain conditions can allow an infection to occur. For example, a scratch can leave the cornea open to infection. A very dry eye can also decrease the cornea's protective mechanisms.

Risk factors that increase the likelihood of developing this condition include:

  • poor contact lens care; overuse of contact lenses
  • illnesses or other factors that reduces the body's ability to overcome infection
  • cold sores, genital herpes, and other viral infections
  • crowded, dirty living conditions; poor hygiene
  • poor nutrition (especially a deficiency of Vitamin A, which is essential for normal vision)

Some common types of keratitis are listed below, however there are many other forms.

Herpes simplex keratitis

A major cause of adult eye disease, herpes simplex keratitis may lead to:

  • chronic inflammation of the cornea
  • development of tiny blood vessels in the eye
  • scarring
  • loss of vision
  • glaucoma

This infection generally begins with inflammation of the membrane lining the eyelid (conjunctiva) and the portion of the eyeball that comes into contact with it. It usually occurs in one eye. Subsequent infections are characterized by a pattern of lesions that resemble the veins of a leaf. These infections are called dendritic keratitis and aid in the diagnosis.

Recurrences may be brought on by stress, fatigue, or ultraviolet light (UV) exposure (e.g., skiing or boating increase the exposure of the eye to sunlight; the sunlight reflects off of the surfaces). Repeated episodes of dendritic keratitis can cause sores, permanent scarring, and numbness of the cornea.

Recurrent dendritic keratitis is often followed by disciform keratitis. This condition is characterized by clouding and deep, disc-shaped swelling of the cornea and by inflammation of the iris.

It is very important not to use topical corticosteroids with herpes simplex keratitis as it can make it much worse, possibly leading to blindness.

Bacterial keratitis

People who have bacterial keratitis wake up with their eyelids stuck together. There can be pain, sensitivity to light, redness, tearing, and a decrease in vision. This condition, which is usually aggressive, can be caused by wearing soft contact lenses overnight. One study found that overnight wear can increase risk by 10-15 times more than if wearing daily wear contact lenses. Improper lens care is also a factor. Contaminated makeup can also contain bacteria.

Bacterial keratitis makes the cornea cloudy. It may also cause abscesses to develop in the stroma, which is located beneath the outer layer of the cornea.

Fungal keratitis

Usually a consequence of injuring the cornea in a farm-like setting or in a place where plant material is present, fungal keratitis often develops slowly. This condition:

  • usually affects people with weakened immune systems
  • often results in infection within the eyeball
  • may cause stromal abscesses
Peripheral ulcerative keratitis

Peripheral ulcerative keratitis is also called marginal keratolysis or peripheral rheumatoid ulceration. This condition is often associated with active or chronic:

  • rheumatoid arthritis
  • relapsing polychondritis (connective-tissue inflammation)
  • wegener's granulomatosis, a rare condition characterized by kidney disease and development of nodules in the respiratory tract
Superficial punctate keratitis

Often associated with the type of viruses that cause upper respiratory infection (adenoviruses), superficial punctate keratitis is characterized by destruction of pinpoint areas in the outer layer of the cornea (epithelium). One or both eyes may be affected.

Acanthamoeba keratitis

This pus-producing condition is very painful. It is a common source of infection in people who wear soft or rigid contact lenses. It can be found in tap water, soil, and swimming pools.

Photokeratitis

Photokeratitis or snowblindness is caused by excess exposure to UV light. This can occur with sunlight, suntanning lamps, or a welding arc. It is called snowblindness because the sunlight is reflected off of the snow. It therefore can occur in water sports as well, because of the reflection of light off of the water. It is very painful and may occur several hours after exposure. It may last one to two days.

Interstitial keratitis

Also called parenchymatous keratitis, interstitial keratitis is a chronic inflammation of tissue deep within the cornea. Interstitial keratitis is rare in the United States. Interstitial keratitis affects both eyes and usually occurs as a complication of congenital or acquired syphilis. In congenital syphilis it can occur between age two and puberty. It may also occur in people with tuberculosis, leprosy, or other diseases.

— Maureen Haggerty



 
 
Dictionary: ker·a·ti·tis  (kĕr'ə-tī'tĭs) pronunciation
n.

Inflammation of the cornea.


 
Dental Dictionary: keratitis

n

Any inflammation of the cornea.

 

Inflammation of the cornea (see eye). The conjunctiva may also be inflamed (keratoconjunctivitis). Depending on the cause, including dryness of the eye (from low tear production or inability to close the eye), chemical or physical injury, or certain diseases, it may or may not cause pain, visual-field defects (including blindness), and damage to the eye.

For more information on keratitis, visit Britannica.com.

 

Inflammation of the cornea of the eye. It may be caused by trauma, exposure to dust or ultraviolet light, or extreme cold. Participants of winter sports such as skiing are particularly at risk. Keratitis can be avoided by wearing appropriate protective glasses. See also snow-blindness.

 
Wikipedia: keratitis
Keratitis
Classification & external resources
Clare-314.jpg
An eye with non-ulcerative sterile keratitis.
ICD-10 H16.
ICD-9 370

Keratitis is a condition in which the eye's cornea is inflamed.

Types

Superficial keratitis involves the superficial layers of the cornea. After healing, this form of keratitis does not generally leave a scar.

Deep keratitis involves deeper layers of the cornea, leaving a scar upon healing that impairs vision if on or near the visual axis.

Causes

Keratitis has multiple causes, one of which is an infection of a present or previous herpes simplex virus secondary to an upper respiratory infection, involving cold sores.

Pathogens

Other

Symptoms

The symptoms are often very similar to those of conjunctivitis, an inflammation of the conjunctiva, and photophobia. The eye turns very red and there may be sensitivity to light, and the eye may feel uncomfortable. In the later stages of more severe cases, there can be strong pain, loss of vision/blurriness, and pus may form.

Diagnosis

Effective diagnosis is important in detecting this condition and subsequent treatment as keratitis is sometimes mistaken for an allergic conjunctivitis.

Treatment

Treatment depends on the cause of the keratitis.

Infectious keratitis generally requires antibacterial, antifungal, or antiviral therapy is to treat the infection. This treatment can involve prescription eye drops, pills, or even intravenous therapy. Over-the-counter eye drops are typically not helpful in treating infections. In addition, contact lens wearers are typically advised to discontinue contact lens wear and discarding contaminated contact lenses and contact lens cases. Antibacterial solutions include Quixin (levofloxacin), Zymar (gatifloxacin), Vigamox (moxifloxacin), Ocuflox (ofloxacin — available generically). Steroid containing medications should not be used for bacterial infections, as they may exacerbate the disease and lead to severe corneal ulceration and corneal perforation. These include Maxitrol (neomycin+polymyxin+dexamethasone — available generically), as well as other steroid medications. One should consult a qualified Ophthalmologist for treatment of an eye condition.

Some infections may scar the cornea to limit vision. Others may result in perforation of the cornea, endophthalmitis (an infection inside the eye), or even loss of the eye. With proper medical attention, infections can usually be successfully treated without long-term visual loss.


See also

External links


 
 

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Copyrights:

Medical Encyclopedia. © 2006 through a partnership of Answers Corporation. All rights reserved.  Read more
Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved.  Read more
Dental Dictionary. Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved.  Read more
Britannica Concise Encyclopedia. Britannica Concise Encyclopedia. © 2006 Encyclopædia Britannica, Inc. All rights reserved.  Read more
Sports Science and Medicine. The Oxford Dictionary of Sports Science & Medicine. Copyright © Michael Kent 1998, 2006, 2007. All rights reserved.  Read more
Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Keratitis" Read more

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