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. Center for Disease Control issued a health advisory due to increased risk of Acanthamoeba keratitis associated with use of Advanced Medical Optics Complete Moisture Plus Multi-Purpose eye solution. Parasitic
Onchocercal keratitis, which follows Onchocerca volvulus infection by infected blackfly bite.
Removable plastic stents are used in uncomplicated gallstone disease, while permanent self-expanding metal stents with a longer lifespan are used if the obstruction is due to pressure from a tumor such as pancreatic cancer. A nasobiliary drain may be left behind; this is a plastic tube that passes from the bile duct through the stomach and the nose and allows continuous drainage of bile into a receptible. It is similar to a nasogastric tube, but passes into the common bile duct directly, and allows for serial x-ray cholangiograms to be done to identify the improvement of the obstruction. The decision on which of the aforementioned treatments to apply is generally based on the severity of the obstruction, findings on other imaging studies, and whether the patient has improved with antibiotic treatment. Certain treatments may be unsafe if blood clotting is impaired, as the risk of bleeding (especially from sphincterotomy) is increased in the use of medication such as clopidogrel (which inhibits platelet aggregation) or if the prothrombin time is significantly prolonged. For a prolonged prothrombin time, vitamin K or fresh frozen plasma may be administered to reduce bleeding risk. Percutaneous biliary drainage
In cases where a person is too ill to tolerate endoscopy or when a retrograde endoscopic approach fails to access the obstruction, a percutaneous transhepatic cholangiogram (PTC) may be performed to evaluate the biliary system for placement of a percutaneous biliary drain (PBD).