This patient-education article is written by the cornea service at Suraj Eye Institute, Nagpur.

What is Bacterial Keratitis?

Bacterial keratitis is an infection of the cornea by bacteria. It is a sight-threatening emergency: the cornea has no blood supply of its own, so infection can spread rapidly, destroy stromal tissue and cause permanent scarring or perforation within days. It must be diagnosed at the slit-lamp and treated with intensive topical antibiotics — usually with no delay for laboratory results.

The most common organisms are Staphylococcus aureus, coagulase-negative staphylococci, Streptococcus pneumoniae and (especially in contact-lens-related disease) Pseudomonas aeruginosa.

Bacterial Corneal Ulcer — External Appearance

Bacterial Corneal Ulcer — Slit-Lamp Appearance

Hypopyon

Epithelial defect (stains green with fluorescein)

Stromal infiltrate (white/grey corneal haze)

Pus settled in anterior chamber

Figure 1. A typical bacterial corneal ulcer. The epithelium is broken (the green-staining defect in the centre), the underlying stroma is white and hazy from infiltrate (immune cells responding to the bacteria), and pus has settled out as a layered hypopyon in the lower anterior chamber. The conjunctiva is intensely red and the eye is painful and photophobic.

Risk Factors

  • Contact lens wear — particularly overnight wear, swimming in lenses, poor case hygiene
  • Recent corneal trauma, however minor
  • Pre-existing ocular surface disease (severe dry eye, exposure, blepharitis)
  • Previous corneal surgery, including keratoplasty
  • Topical steroid use
  • Immunosuppression

Symptoms

Bacterial keratitis presents acutely with severe eye pain, redness, photophobia, watering, mucopurulent discharge and reduced vision. A visible white spot on the cornea is the hallmark sign.

How Bacterial Keratitis is Diagnosed

Diagnosis is made at the slit-lamp by the characteristic combination of an epithelial defect overlying a stromal infiltrate. The location, depth, density and any surrounding satellites are recorded carefully. A corneal scraping is taken in all but the smallest ulcers and sent for smear and culture, so that empirical treatment can be refined when sensitivity results return.

Treatment

Bacterial keratitis is treated as an emergency:

  • Fortified topical antibiotics — combination of fortified cefazolin 5 % and fortified tobramycin (or gentamicin) every hour around the clock initially, OR moxifloxacin / besifloxacin monotherapy as an alternative depending on size and risk
  • Cycloplegic drops for pain relief and to prevent posterior synechiae
  • Daily slit-lamp review in the first few days — the ulcer should not be enlarging once treatment is established
  • Topical steroids are added only after the infection is clearly controlled, to reduce scarring
  • Therapeutic surgery — amniotic membrane grafting for slow-healing defects; therapeutic keratoplasty for impending or actual perforation
If you wear contact lenses and have a painful red eye — remove the lens and come in straight away. Do not wait for the next day. Contact-lens-related Pseudomonas keratitis can perforate the cornea within 48 hours.
✔ Bacterial Keratitis Care at Suraj Eye Institute

We treat bacterial keratitis as an emergency. Our on-site microbiology service receives corneal scrapings without delay, our pharmacy prepares fortified topical antibiotics in-house, and our cornea consultants supervise intensive treatment and, where needed, emergency amniotic membrane grafting or therapeutic corneal transplantation for impending or actual perforation.

Book a Cornea Consultation

Frequently Asked Questions

My eye just feels gritty — can I wait until tomorrow?
If you wear contact lenses, no. Contact-lens-related Pseudomonas keratitis can advance dramatically overnight. For non-lens-wearers with mild discomfort the priority is still same-day or next-morning assessment; pain, photophobia, blurring or a visible white spot on the eye should never be left untreated.

Why are you using antibiotic drops every hour?
Hourly fortified antibiotics are needed because the cornea has no blood supply. The only way the antibiotic reaches the infection is by diffusion from the tear film, and the drug is washed away quickly. Frequent dosing is essential during the first few days.

Will I be able to see normally again?
Most small, peripheral ulcers heal with little or no permanent visual effect. Larger or central ulcers heal with a scar that may reduce vision; in some cases a corneal transplant is needed later for visual rehabilitation. Early and intensive treatment gives the best chance of preserving vision.

Do I really need a corneal scrape?
For any ulcer that is more than a small superficial epithelial defect, yes — a scrape allows the microbiology lab to identify the organism and tailor treatment if recovery is slower than expected. The scrape is taken under topical anaesthetic and is well tolerated.

Can I keep wearing my contact lenses after this heals?
After a contact-lens-related ulcer we recommend stopping lens wear for at least a month, switching to daily disposables once cleared, and reviewing lens hygiene carefully. In many cases switching from monthly to daily disposable lenses is the safest long-term change.

← Back to All Cornea Topics