Describe the Epidemiology and Etiology.
Epidemiology: most common form of keratitis (∼ 90%) 
Mainly: staphylococci (Staphylococcus aureus), streptococci (Streptococcus pneumoniae), Pseudomonas aeruginosa
Enterobacteriaceae (including Klebsiella)
Contact lens use
Recent eye surgery or injury
Lacrimal duct stenosis
List clinical features and describe subtypes.
Foreign body sensation
Subtypes and variants: Pseudomonas keratitis
Caused by Pseudomonas aeruginosa
Most common cause of bacterial keratitis in contact lens users 
Fulminant course with severe ulceration
Corneal destruction/perforation within 2–5 days 
Describe the diagnostics.
Slit lamp examination
Hypopyon: collection of leukocytes at the bottom of the anterior chamber; occurs in severe cases of keratitis
Fluorescein staining: round corneal infiltrate or ulcer
Creeping ulcer or serpiginous corneal ulcer in pneumococcus infection
(Ring‑) ulcer: (ring-shaped) spread of the pathogen in the cornea
Thygeson superficial punctate keratitis: point-shaped lesions in the corneal epithelium
Cultures are indicated when the corneal infiltrate is large, central, and extends to the deep stroma, for refractory cases, or those with atypical features. 
Describe the treatment.
Topical broad-spectrum antibiotics 
Cefazolin with tobramycin/gentamicin or
Consider corticosteroids following identification of pathogen and ∼2 days of antibiotic therapy
Therapeutic mydriasis may be considered
Corneal transplantation in threatened or existing large perforations, small corneal perforations with consistent bacterial growth, or suppuration despite antibiotics 
Describe the prevention and complications.
Prevention: Education on contact lens hygiene
Irreversible vision loss
Corneal destruction (potentially leading up to perforation)
Leukoma: a dense, white opacity of the cornea caused by scarring
Caused by inflammation, injuries, or congenital corneal conditions.
Adherent leukoma: part of the iris is attached to the cornea
Vascularization into the cornea
↑ Intraocular pressure; if necessary, reduce intraocular pressure during the acute phase