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, red eye and a 'gritty' sensation.
Herpes simplex keratitis. Viral infection of the cornea is often caused by the herpes simplex virus which frequently leaves what is called a 'dendritic ulcer'.
Bacterial keratitis. Bacterial infection of the cornea can follow from an injury or from wearing contact lenses. The bacteria involved are Staphylococcus aureus and for contact lens wearers, Pseudomonas aeruginosa. Pseudomonas aeruginosacontains enzymes that can digest the cornea.
Fungal
Fungal keratitis, caused by Aspergillus fumigatus and Candida albicans
Amoebic
Acanthamoebic keratitis
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".
Exposure keratitis — due to dryness of the cornea caused by incomplete or inadequate eyelid closure.
Photokeratitis — keratitis due to intense ultraviolet radiation exposure
Contact lens acute red eye — a non-ulcerative sterile keratitis associated with colonization of Gram-negative bacteria on contact lenses.
Treatment
Treatment depends on the cause of the keratitis. Infectious keratitis can progress rapidly, and generally requires urgent antibacterial, antifungal, or antiviral therapy to eliminate the pathogen. Antibacterial solutions include levofloxacin, gatifloxacin, moxifloxacin, ofloxacin. It is unclear if steroideye drops are useful or not. In addition, contact lens wearers are typically advised to discontinue contact lens wear and replace contaminated contact lenses and contact lens cases.. Aciclovir is the mainstay of treatment for HSV keratitis and steroids should be avoided at all costs in this condition. Application of steroids to a dendritic ulcer caused by HSV will result in rapid and significant worsening of the ulcer to form an 'amoeboid' or 'geographic' ulcer, so named because of the ulcer's map like shape.
Prognosis
Some infections may scar the cornea to limit vision. Others may result in perforation of the cornea, endophthalmitis, or even loss of the eye. With propermedical attention, infections can usually be successfully treated without long-termvisual loss.
