Table of contents

Bacterial keratitis



Bacterial keratitis is a corneal infection caused by bacteria, characterized by pain, redness, inflammation, and opacity of the cornea.
The pathophysiology of bacterial keratitis involves the entry of bacteria into the cornea, often facilitated by a disruption in the ocular epithelial surface. The bacteria then proliferate and release tissue-damaging proteases and toxins, leading to an inflammatory response.
The incidence of keratitis in the US is estimated at 27.6 per 100,000 person-years.
Disease course
Clinically, patients with bacterial keratitis often present with symptoms such as pain, redness, discharge, blurred vision, and photophobia. On examination, suppurative stromal infiltrates with indistinct edges, corneal edema, and white cell infiltration in the surrounding stroma are often observed. An epithelial defect is typically present, and an anterior chamber reaction is often observed.
Prognosis and risk of recurrence
The prognosis of bacterial keratitis can vary, but it can lead to severe visual impairment if not treated promptly.


Key sources

The following summarized guidelines for the evaluation and management of bacterial keratitis are prepared by our editorial team based on guidelines from the American Academy of Ophthalmology (AAO 2022,2019), the College of Optometrists (CO 2022), and the American Academy of Family Physicians (AAFP 2016). ...
Show more

Diagnostic investigations

History and physical examination: as per AAO 2019 guidelines, elicit a detailed history in patients with suspected bacterial keratitis, including:
Ocular symptoms
Degree of pain, redness, discharge, blurred vision, and photophobia
Duration of symptoms
Circumstances surrounding the onset of symptoms
Contact lens history
Wearing schedule, overnight wear
Type of contact lens, contact lens solution
Contact lens hygiene protocol, tap-water rinsing of contact lenses
Swimming, using a hot tub, or showering while wearing contact lenses
Method of purchase, such as over the Internet
Decorative contact lens use
Review of ocular history
HSV keratitis
VZV keratitis
Previous bacterial keratitis
Eye trauma
Dry eye
Previous ocular surgery, including refractive and facial (including laser cosmetic) surgery
Review of other medical issues
Immune status
Systemic medications
History of MRSA or other multidrug-resistant infections
Medication history
Current and recently used ocular medications
Medication allergies
Show 3 more
Create free account

More topics in this section

  • Corneal culture

Diagnostic procedures

Corneal biopsy
As per AAO 2019 guidelines:
Consider performing a corneal biopsy in patients with poor response to treatment or if the clinical picture strongly suggests an infectious process despite repeated negative cultures.
Consider performing a corneal biopsy in patients with an infiltrate located in the mid or deep stroma with overlying uninvolved tissue.

More topics in this section

  • Anterior chamber paracentesis

Medical management

Topical antibiotics: as per AAO 2022 guidelines, offer fluoroquinolone-containing, single-agent topical antibiotics in patients with bacterial keratitis.

More topics in this section

  • Topical corticosteroids

  • Cycloplegics

  • Systemic antibiotics

Nonpharmacologic interventions

Cessation of contact lens wear: as per CO 2022 guidelines, advise ceasing contact lens wear in patients with microbial keratitis. Instruct contact lens wearers to retain their lenses and lens cases in case needed for culture.

More topics in this section

  • Ocular lubricants

Therapeutic procedures

Subconjunctival antibiotics: as per AAO 2019 guidelines, consider administering subconjunctival antibiotic injections in patients with imminent scleral spread or perforation or if adherence to treatment is questionable.

Specific circumstances

Patients with marginal keratitis: as per CO 2022 guidelines, advise regular lid hygiene for associated blepharitis.
Show 4 more

Preventative measures

Proper contact lens use: as per AAO 2019 guidelines, counsel contact lens users about the risks of overnight wear of contact lenses and proper contact lens care to reduce the incidence of bacterial keratitis.

More topics in this section

  • Avoidance of eye patching

  • Prophylactic antibiotics