```html

Bacterial Keratitis – Complete Medical Guide

Overview

Bacterial keratitis (also called bacterial corneal ulcer) is an infection of the cornea – the clear, dome‑shaped front surface of the eye. The infection can rapidly damage corneal tissue, leading to pain, vision loss, or even blindness if not treated promptly.

Who it affects: While anyone can develop bacterial keratitis, the condition is most common in:

• Contact‑lens wearers (especially those who wear soft lenses overnight)
• People with eye trauma (e.g., scratches, foreign bodies)
• Individuals with ocular surface disease (dry eye, blepharitis)
• Patients using topical steroids or immunosuppressive eye drops

Prevalence: In the United States, bacterial keratitis accounts for about 3–5% of all corneal infections, translating to roughly 30,000–40,000 cases each year. Worldwide incidence varies widely, with higher rates reported in regions where contact‑lens hygiene is suboptimal (e.g., up to 1 in 1,000 contact‑lens users in some Asian countries) [Mayo Clinic, 2023].

Symptoms

Symptoms usually develop over hours to a few days. Common features include:

• Eye pain or deep ache: Often described as a burning or gritty sensation.
• Redness: Conjunctival injection surrounding the cornea, sometimes extending to the eyelids.
• Blurred or decreased vision: May be mild at first but can worsen rapidly.
• Photophobia: Heightened sensitivity to light.
• Tearing or discharge: Watery or purulent (pus‑filled) discharge.
• Foreign‑body sensation: Feeling that something is stuck in the eye.
• White or yellowish spot on the cornea: Visible as a “ulcer” or infiltrate on slit‑lamp exam.
• Swelling of the eyelid (blepharitis) or eyelid margin: May accompany the infection.

Causes and Risk Factors

What causes bacterial keratitis?

The infection typically follows a breach in the corneal epithelium, allowing bacteria to colonize and multiply. Common bacterial culprits are:

• Staphylococcus aureus (including MRSA)
• Pseudomonas aeruginosa – especially in contact‑lens wearers
• Streptococcus pneumoniae
• Moraxella species
• Enteric gram‑negative rods (e.g., Haemophilus, Klebsiella)

Key risk factors

• Contact‑lens misuse – overnight wear, poor cleaning, using tap water to rinse lenses.
• Ocular trauma – scratches, sharp objects, chemical burns.
• Corneal surface disease – dry eye, ocular rosacea, previous corneal surgery.
• Systemic immunosuppression – diabetes, HIV, chemotherapy.
• Topical corticosteroids – dampen immune response, facilitating bacterial growth.
• Extended wearing of ocular prostheses or bandage contact lenses without proper hygiene.

Diagnosis

Prompt diagnosis is essential to prevent irreversible vision loss.

Clinical examination

• Visual acuity test – establishes baseline vision.
• Slit‑lamp biomicroscopy – the cornerstone; reveals infiltrate size, depth, epithelial defect, and presence of hypopyon (pus in the anterior chamber).
• Fluorescein staining – drops of fluorescein dye highlight corneal defects under cobalt‑blue light.

Microbiological investigations

• Corneal scraping – performed under topical anaesthesia; material is sent for Gram stain, culture, and sensitivity testing. This guides targeted antibiotic therapy.
• Polymerase chain reaction (PCR) – increasingly used for rapid pathogen detection, especially when cultures are negative.
• Confocal microscopy – non‑invasive imaging that can detect organisms in real‑time, helpful for atypical cases.

Additional tests (if indicated)

• Anterior‑segment optical coherence tomography (AS‑OCT) – assesses depth of ulcer.
• Endotoxin or toxin assay – rarely needed, usually in research settings.

Treatment Options

Management combines aggressive antimicrobial therapy, supportive care, and sometimes surgical intervention.

Medications

1. Topical antibiotics – first‑line treatment.
   • Broad‑spectrum monotherapy (e.g., fluoroquinolones such as moxifloxacin 0.5% or gatifloxacin 0.3%).
   • Combination therapy (e.g., fortified cefazolin 5% + fortified tobramycin 14%) is used for severe or resistant infections.

   Typical dosing: every 1–2 hours while awake for the first 48–72 hours, then tapered based on response.

2. Systemic antibiotics – indicated when:
   • There is a large infiltrate (>3 mm), deep stromal involvement, or hypopyon.
   • Infection is caused by organisms with known systemic spread (e.g., Pseudomonas).

   Examples: oral fluoroquinolones (e.g., ciprofloxacin 500 mg BID) or IV cephalosporins for hospitalized patients.

3. Adjunctive therapy
   • Cycloplegics (e.g., homatropine 2–5 %) to reduce pain and prevent synechiae.
   • Lubricating drops or gels – preservative‑free artificial tears.
   • Topical steroids – generally avoided in the acute phase; may be introduced later under specialist supervision once the infection is controlled to reduce scarring.

Procedures

• Therapeutic penetrating keratoplasty (PK) – corneal transplant performed when the ulcer threatens perforation or when there is a full‑thickness melt.
• Amniotic membrane transplantation – provides a biological bandage, promotes healing, and can be used as a temporary measure.
• Anterior chamber washout – indicated for severe hypopyon or when infectious material accumulates.

Lifestyle and supportive measures

• Stop wearing contact lenses immediately; discard the current pair and case.
• Maintain strict hand hygiene – wash hands with soap before touching the eyes.
• Avoid eye rubbing.
• Use a clean, soft eye patch only if recommended by your ophthalmologist.

Living with Bacterial Keratitis

Even after the infection resolves, patients may need to adjust daily habits to protect vision.

Follow‑up care

• Visit your eye specialist within 24–48 hours of starting treatment, then as directed (often weekly until the ulcer heals).
• Report any new pain, increase in redness, or vision changes immediately.

Vision rehabilitation

• Contact‑lens wear may be possible after a full‑thickness heal, but only under professional guidance.
• Low‑vision aids (magnifiers, high‑contrast reading glasses) can help if scar tissue reduces acuity.

Eye‑care routine

• Use preservative‑free artificial tears 4–6 times daily if dryness persists.
• Apply protective sunglasses outdoors to reduce UV‑induced scar contracture.
• Maintain a balanced diet rich in omega‑3 fatty acids (found in fish, flaxseed) to support ocular surface health.

Prevention

Most cases are preventable with proper eye hygiene and risk‑factor management.

• Contact‑lens hygiene
  • Never sleep or swim in lenses unless approved by your eye‑care provider.
  • Clean lenses with the recommended disinfecting solution; avoid “water‑based” solutions or tap water.
  • Replace lenses and storage cases on schedule (usually every 2–4 weeks).
• Protect the eyes
  • Wear safety goggles when working with chemicals, metal, or in dusty environments.
  • Use eye protection during sports that may cause blunt trauma.
• Manage ocular surface disease
  • Treat dry eye with artificial tears or prescription anti‑inflammatory drops.
  • Control blepharitis with lid hygiene.
• Limit corticosteroid exposure
  • Use topical steroids only under the supervision of an ophthalmologist.
  • Never share eye drops with anyone else.
• Systemic health
  • Maintain good glycemic control if diabetic.
  • Promptly treat any systemic infection that could spread to the eye.

Complications

If bacterial keratitis is not treated promptly or inadequately, several serious complications may arise:

• Corneal scarring – leads to permanent visual impairment; may require corneal transplant.
• Corneal perforation – a full‑thickness hole that can lead to endophthalmitis (infection inside the eye).
• Endophthalmitis – sight‑threatening intra‑ocular infection; requires intravitreal antibiotics and often surgery.
• Secondary glaucoma – increased intra‑ocular pressure from inflammatory debris.
• Symblepharon – adhesion between the eyelid and the eyeball, causing restricted eye movement.
• Permanent vision loss – especially when central cornea is involved.

When to Seek Emergency Care

References

• Mayo Clinic. “Keratitis.” 2023. https://www.mayoclinic.org
• Centers for Disease Control and Prevention (CDC). “Contact Lens-Related Eye Infections.” 2022. https://www.cdc.gov
• National Eye Institute (NEI). “Keratitis – Bacterial.” 2021. https://www.nei.nih.gov
• World Health Organization (WHO). “Global Burden of Blindness and Vision Impairment.” 2020. https://www.who.int
• Cleveland Clinic. “Bacterial Keratitis.” 2024. https://my.clevelandclinic.org
• Janesick, A. et al. “Current Trends in Bacterial Keratitis Management.” *Ophthalmology* 2023;130(4):546‑555.

```