Keratitis

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Keratitis is an inflammation of the cornea, which may be infectious or non infectious, leading to pain, redness, visual disturbances, and potential complications such as corneal ulceration and scarring.

Aetiology

  • Infectious causes:
    • Bacterial: Staphylococcus aureus, Pseudomonas aeruginosa (common in contact lens wearers).
    • Viral: Herpes simplex virus (HSV), varicella-zoster virus.
    • Fungal: Aspergillus, Candida (common in immunocompromised individuals).
    • Protozoal: Acanthamoeba (associated with contaminated water exposure in contact lens users).
  • Non-infectious causes:
    • Corneal trauma (e.g., foreign body, chemical injury).
    • Exposure keratitis (due to incomplete eyelid closure).
    • Allergic keratitis (hypersensitivity reaction).
    • Autoimmune conditions (e.g., rheumatoid arthritis, Sjögren’s syndrome).

Pathophysiology

  • Inflammation of the cornea disrupts the protective epithelial barrier.
  • Infectious agents or trauma trigger immune responses, leading to corneal oedema and ulceration.
  • Severe cases may result in corneal perforation, scarring, or endophthalmitis.

Risk Factors

  • Contact lens use, especially overnight wear or poor hygiene.
  • Ocular trauma or surgery.
  • Immunosuppression (HIV, diabetes, corticosteroid use).
  • Exposure to contaminated water (e.g., swimming, hot tubs).
  • Chronic dry eye or lagophthalmos.

Signs and Symptoms

  • Eye pain and redness.
  • Photophobia and excessive tearing.
  • Blurred vision.
  • Foreign body sensation.
  • Corneal opacity or ulceration in severe cases.
  • Dendritic ulcers (in herpetic keratitis).

Investigations

  • Slit-lamp examination: evaluates corneal defects, infiltrates, and ulcers.
  • Fluorescein staining: identifies epithelial defects (e.g., dendritic pattern in HSV keratitis).
  • Corneal scraping: for gram stain, culture, and sensitivity in suspected bacterial or fungal infections.

Management

1. General Management:

  • Urgent ophthalmology referral if ulceration or suspected microbial keratitis.
  • Avoid contact lens use until resolution.
  • Analgesia (topical lubricants, systemic analgesics if needed).

2. Infectious Keratitis:

  • Bacterial: topical broad spectrum antibiotics (e.g., levofloxacin, ciprofloxacin).
  • Viral: topical or oral aciclovir for herpes simplex keratitis. For example, aciclovir 3% ointment five times daily for 2weeks.
  • Fungal: topical antifungals (follow local guidelines).
  • Protozoal (Acanthamoeba): chlorhexidine 0.02% or polyhexamethylene biguanide 0.02% (PHMB).

3. Non-infectious Keratitis:

  • Exposure keratitis: lubricants, moisture chambers, or eyelid surgery if severe.
  • Allergic keratitis: antihistamines, mast cell stabilisers.
  • Autoimmune keratitis: immunosuppressive therapy (steroids, cyclosporine).

4. Referral:

  • Ophthalmology: all cases with suspected infectious keratitis, corneal ulceration, or vision threatening involvement.
  • Microbiology: if keratitis is refractory to initial antimicrobial treatment.
  • Immunology: if underlying autoimmune disease is suspected.
Eye DiseasesmypanotesKeratitis