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What is Keratitis and explain in detail?
Keratitis is a condition in which the eyes 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.

Classification (by chronicity)
Acute
Acute epithelial keratitis
Nummular keratitis
Interstitial keratitis
Disciform keratitis

Chronic
Neurotrophic keratitis
Mucous plaque keratitis

Classification (infective)
Viral
Herpes simplex keratitis (dendritic keratitis). Viral infection of the cornea is often caused by the herpes simplex virus (HSV) which frequently leaves what is called a dendritic ulcer.
Herpes zoster keratitis, associated with herpes zoster ophthalmicus, which is a form of shingles.

Bacterial
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 aeruginosa contains enzymes that can digest the cornea.

Fungal
Fungal keratitis, caused by Aspergillus fumigatus and Candida albicans (cf. Fusarium, causing an outbreak of keratitis in 2005–2006 through the possible vector of Bausch & Lomb ReNu with MoistureLoc contact lens solution)

Amoebic
Acanthamoebic keratitis
Amoebic infection of the cornea is a serious corneal infection, often affecting contact lens wearers. It is usually caused by Acanthamoeba. On May 25, 2007, the U.S