Keratitis

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

 * Amoebic keratitis. Amoebic infection of the cornea is the most serious corneal infection, usually affecting soft contact lens wearers. It is usually caused by Acanthamoeba. On May 25, 2007, the CDC issued a health advisory due to increased risk of Acanthamoeba keratitis (AK)infection associated with use of Advanced Medical Optics (AMO) Complete Moisture Plus Multi-Purpose eye solution. See CDC Advisory
 * Bacterial keratitis. Bacterial infection of the cornea can follow from an injury or from wearing contact lenses. The bacteriums usually involved are Staphylococcus aureus and for contact lens wearers Pseudomonas aeruginosa.
 * Fungal keratitis (cf. Fusarium, causing recent incidences of keratitis through the possible vector of Bausch & Lomb ReNu with MoistureLoc contact lens solution)
 * Viral keratitis
 * 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'.
 * Herpes zoster keratitis

Other

 * Exposure keratitis
 * Photokeratitis - keratitis due to intense ultraviolet radiation exposure (e.g. snow blindness or welder's arc eye.)
 * Ulcerative keratitis
 * Contact lens acute red eye (CLARE) - a non-ulcerative sterile keratitis associated with colonization of Gram-negative bacteria on contact lenses
 * Severe allergic response may lead to corneal inflammation and ulceration (i.e. vernal keratoconjunctivitis).

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 &mdash; 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 &mdash; 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.