Major cause of impaired vision and blindness worldwide
Break in epithelial layer allows infectious agents to gain access to the underlying stroma
Risk factors include:  incomplete lid closure (e.g. secondary to Bell's palsy) and soft contact lens use (especially sleeping in contacts)
Bacteria
Pseudomonas
Strep pneumo
Staph
Moraxella
Viruses
Herpes simplex
Varicella-zoster
Fungi
Candida
Aspergillus
Penicillium
Cephalosporium
Pseudomonas
Strep pneumo
Staph
Moraxella
Herpes simplex
Varicella-zoster
Candida
Aspergillus
Penicillium
Cephalosporium
Corneal ulcer
Nontraumatic
Corneal abrasion
Acute angle-closure glaucoma^
Periorbital cellulitis
Anterior uveitis
Sympathetic ophthalmia
Conjunctivitis