By far the most common cause of<unk>  is syphilitic disease. However, there are two possible causes of the corneal inflammatory response: an infection and/or an immunological response, such as a hypersensitivity type reaction, or (rarely) Cogan syndrome. Infectious causes include syphilis (commonest), followed by other bacterial infections (TB, Leprosy and Lyme disease) and parasitic infections (Acanthamoeba, Onchocerciasis or river blindness, Leishmaniasis, Trypanosoma cruzi or Chagas disease, Trypanosoma brucei or African sleeping sickness and microsporidia)
Interstitial keratitis
Peripheral ulcerative keratitis
Nummular keratitis
Neurotrophic keratitis
Granular corneal dystrophy
Diffuse lamellar keratitis
Lattice corneal dystrophy
Macular corneal dystrophy