Condition in which the cornea is inflamed, and is often associated intense pain and usually involves any of the following symptoms: pain, impaired eyesight, photophobia, red eye and a ‘gritty’ sensation.
Corneal infection, infectious keratitis, can cause vision loss through corneal scarring or perforation.
Keratitis is mostly due to infection, and is estimated to account for approximately 1 million healthcare visit in the US annually.
Symptoms of keratitis include: photophobia, unilateral eye pain, redness, and decreased vision.
Sudden onset of eye pain or reduced vision requires prompt referral for eye care.
Infectious keratitis can be categorized as microbial: bacterial, fungal or parasitic, or viral.
Viral infection of the cornea is often caused by the herpes simplex virus which frequently leaves a dendritic ulcer.
Bacterial infection of the cornea can follow an injury or from wearing contact lenses.
The bacteria involved are Staphylococcus aureus..
In contact lens wearers Pseudomonas aeruginosa is frequently associated as it contains enzymes that can digest the cornea.
Amoebic infection of the cornea can affect contact lens wearers.
Onchocercal keratitis follows infection by infected blackfly bite.
Exposure keratitis occurs due to dryness of the cornea caused by incomplete eyelid closure.
Photokeratitis is due to ultraviolet radiation exposure that can occur with snow blindness or welder’s arc eye.
A non-ulcerative sterile keratitis can occur with colonization of Gram-negative bacteria on contact lenses.
Treatment depends on the etiology of the keratitis.
The major risk factor for microbial keratitis is the use of contact lenses, worn by approximately 45 million people in the US.
Estimated incidence of microbial keratitis cases per hundred thousand years in the US in 2010 was 130 among contact lens wearers vs. 14 among nonwearers.
Poor lens care includes sleeping in the lenses, storing them in tapwater and reusing the same lens case for prolonged periods: these factors increase risk of microbial keratitis.
Other risk factors for microbial keratitis include: trauma, corneal abrasions, chronic ocular surface diseases and severe dry.
The major bacterial pathogens are pseudomonas, staphylococcus aureus, and streptococci.
Pseudomonas may cause as many is 40% of contact lens related corneal ulcers and its associated keratitis is often severe.
Other causes of keraititis include fungi and molds.
Infectious keratitis generally requires urgent antibacterial, antifungal, or antiviral therapy.
Antibacterial solutions include levofloxacin, gatifloxacin, moxifloxacin: eyedrops.
Steroid eye drops may or may not be useful.
Patients wearing contact lenses should discontinue use and replace contaminated lenses and cases.
Abnormal lenses and cases should be cultured to isolate pathogens.
The two major causes of viral keratitis are HSV and varicella zoster virus.
Most HSV keratitis results from reactivation of latent HSV type1 from the trigeminal ganglion.
Herpes zoster keratitis is seen in the setting of herpes zoster ophthalmological involvement in the distribution of the trigeminal nerve.
Keratitis occurs in 13–76% of herpes zoster ophthalmic cases.
Acyclovir is the treatment for HSV keratitis.
Ophthalmologic steroids are for HSV keratitis as they may rapidly worsen the ulcer.
Complications may include corneal scarring, perforation, progression of infection into the eye, impaired vision and even loss of the eye.
Most infections are treated successfully without complication.
Infective keratitis is a potentially blinding condition.
The most severe complication of the wearing of contact lenses.
Most cases caused by bacteria, particularly Pseudomonas aeruginosa.
Fungal keratitis less than 5% of cases from contact lens wear.
Majority of fungal cases of keratitis due to trauma, chronic ocular surface disease and the presence of immunocompromised disease.
Most common fungal pathogen is Fusarium species, a ubiquitous filamentous fungi in soil and associated with plant roots.