Keratitis is a condition in which the eye's cornea, the clear dome on the front surface of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves any of the following symptoms: pain, impaired eyesight, photophobia (light sensitivity), red eye and a 'gritty' sensation. Diagnosis of infectious keratitis is usually made clinically based on the signs and symptoms as well as eye examination, but corneal scrapings may be obtained and evaluated using microbiological culture or other testing to identify the causative pathogen.

  • In those who wear contact lenses, bacteria are the most common causative agent of keratitis, with 90% of cases being due to a bacterial pathogen. Of those 90% of cases, Pseudomonas aeruginosa is responsible for 40%. Staph aureus and streptococci are other common bacterial pathogens responsible for infectious keratitis in contact lens wearers.)

Amoebic

  • Acanthamoebic keratitis

thumb|Acanthamoeba keratitis

:* Amoebic infection of the cornea is a serious corneal infection, most often affecting contact lens wearers. It is usually caused by Acanthamoeba. On May 25, 2007, the U.S. Center for Disease Control issued a health advisory due to increased risk of Acanthamoeba keratitis associated with use of Advanced Medical Optics Complete Moisture Plus Multi-Purpose eye solution.

Parasitic

  • Onchocercal keratitis, which follows Onchocerca volvulus infection by infected blackfly bite. These blackfly, Simulium, usually dwell near fast-flowing African streams, so the disease is also called "river blindness".

Microbial keratitis (due to bacterial, fungal, or parasitic pathogens), as opposed to viral keratitis, is more commonly associated with the formation of corneal ulcers. Other risk factors for corneal ulcer formation include contact lens use, keratitis in the setting of eye trauma, underlying corneal disease or ocular surface diseases (such as severe chronic dry eye).

In addition, contact lens wearers are typically advised to discontinue contact lens wear and replace contaminated contact lenses and contact lens cases. (Contaminated lenses and cases should not be discarded as cultures from these can be used to identify the pathogen).

Topical ganciclovir or oral valacyclovir, famciclovir or acyclovir are used for HSV keratitis.

Prevention

In those who wear contact lenses, good lens hygiene and storage practices reduce the risk of keratitis. Specific lens care practices which may lead to infectious keratitis include wearing contact lenses overnight or in the shower, not replacing contact lens cases, storing lenses in tap water rather than contact lens solution and topping off lens solution rather than replacing it regularly.

Prognosis

Some infections may scar the cornea, thereby limiting 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.

Acanthamoebic and fungal keratitis are difficult to treat and are associated with a poor prognosis.

See also

  • Keratoconjunctivitis and conjunctivitis
  • Chronic superficial keratitis, or pannus, for the disease in dogs
  • Keratoendotheliitis fugax hereditaria
  • Punctate epithelial erosions
  • Thygeson's superficial punctate keratopathy

References

  • Facts About the Cornea and Corneal Disease The National Eye Institute (NEI)
  • Filimentary keratitis