Keratitis

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

Definition

Keratitis is an inflammation of the cornea, the clear, dome-shaped surface that covers the front of the eye. It can be caused by infections, injuries, or underlying medical conditions, leading to pain, redness, and potential vision loss if untreated.

Aetiology

Keratitis can be classified based on its cause:

• Infectious Keratitis: Caused by bacteria, viruses, fungi, or parasites. Common pathogens include:
  • Pseudomonas aeruginosa
  • Herpes simplex virus (HSV)
  • Acanthamoeba
  • Fusarium and Aspergillus species
• Non-infectious Keratitis: Resulting from physical or chemical injury, prolonged contact lens wear, or underlying autoimmune diseases.

Pathophysiology

The inflammation in keratitis disrupts the normal structure and function of the cornea. In infectious keratitis, pathogens invade the corneal tissue, leading to an immune response that causes inflammation, ulceration, and sometimes scarring. Non-infectious keratitis can result from direct trauma, exposure to irritants, or immune-mediated damage.

Risk Factors

• Contact lens use, especially extended wear or improper hygiene
• Eye injury or trauma
• Exposure to contaminated water (e.g., swimming in lakes or hot tubs with contact lenses)
• Previous eye surgery
• Immune system disorders (e.g., rheumatoid arthritis, Sjögren's syndrome)
• Use of topical corticosteroids

Signs and Symptoms

Common signs and symptoms of keratitis include:

• Eye pain
• Redness of the eye
• Excessive tearing or discharge
• Blurred vision
• Sensitivity to light (photophobia)
• Sensation of a foreign body in the eye
• Decreased visual acuity

Investigations

• Clinical history and physical examination
• Slit-lamp examination to assess the cornea
• Corneal scraping and culture to identify the causative organism in infectious keratitis
• Fluorescein staining to highlight corneal ulcers or defects
• Additional tests for underlying conditions if non-infectious keratitis is suspected

Management

Primary Care Management

• Urgent same-day referral to ophthalmology: For suspected keratitis, especially if vision is significantly affected or if an infectious cause is suspected.

References

1. NICE. (2024). Keratitis: Diagnosis and Management. Retrieved from NICE
2. NHS. (2023). Keratitis. Retrieved from NHS
3. British Medical Journal (BMJ). (2022). Keratitis: Diagnosis and Management. Retrieved from BMJ
4. American Academy of Ophthalmology (AAO). (2021). Clinical Practice Guidelines: Keratitis. Retrieved from AAO

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