Keratitis is caused by

Causes of keratitis   Infective keratitis Bacterial Viral Fungal Chlamydial Protozoal Spirochactal   Allergic keratitis Phlyctenular keratitis Vernal keratitis Atopic keratitis   Trophic keratitis Exposure keratitis Neuroparalytic keratitis Keratomalacia Atheromatous ulcer   Keratitis associated with diseases of skin and mucous membrane. Keratitis associated with systemic collagen vascular disorders. Traumatic keratitis, which may be due to mechanical trauma, chemical trauma, thermal burns, radiations.   Idiopathic keratitis e.g., Mooren's corneal ulcer Superior limbic keratoconjunctivitis Superficial punctate keratitis of Thygeson