A bacterial corneal ulcer, or bacterial keratitis, is an infection of the corneal stroma that causes rapid visual loss and pain. Infectious corneal ulcers need to be treated as soon as possible to preserve vision. If left untreated, a bacterial infection can lead to perforation of the cornea, loss of vision, and even loss of the eye.

Risk factors that can lead to bacterial keratitis include contact lens wear, eye trauma, previous ocular surgery, dry eye, immunosuppression, and any other process that causes breakdown of the ocular surface.

Patients with a bacterial corneal ulcer will complain of eye pain, light sensitivity, red eyes, and possibly reduced vision. The rapidity of the onset and progression of symptoms depends on the virulence of the bacteria causing the infection.

History is very important in giving clues as to the most common organism causing the infection. Bacterial keratitis in a contact lens wearer is frequently caused by gram-negative organisms, such as Pseudomonas aeruginosa, whereas ulcers in patients with blepharitis are more commonly due to gram-positive organisms.

Note: Per January 20, 2023, the Centers for Disease Control and Prevention (CDC) is investigating a multistate cluster of carbapenem-resistant Pseudomonas aeruginosa with Verona integron-mediated metallo-β-lactamase and Guiana extended-spectrum-β-lactamase (VIM-GES-CRPA). As of March 14, 2023, the CDC identified 68 patients in 16 states with with VIM-GES-CRPA. At this time, CDC and FDA recommend clinicians and patients stop using EzriCare or Delsam Pharma's Artificial Tears products. The isolates have remained cefiderocol sensitive.