What is keratitis?

What is Keratitis?

Keratitis is an inflammation or infection of the cornea that can lead to vision loss if not promptly diagnosed and treated. 1 It can be caused by bacteria, viruses, fungi, parasites, or non-infectious factors, and requires immediate medical attention due to the potential for rapid corneal destruction within 24-48 hours.

Types and Causes of Keratitis

Keratitis can be classified into several categories:

1. Based on clinical presentation:

   • Ulcerative keratitis (with epithelial breakdown)
   • Non-ulcerative keratitis (without epithelial breakdown)

2. Based on causative agents:

   • Bacterial keratitis: Commonly caused by:
     • Gram-positive organisms: Staphylococcus species, Streptococcus pneumoniae
     • Gram-negative organisms: Pseudomonas aeruginosa, Neisseria gonorrhoeae
   • Viral keratitis: Primarily caused by herpes simplex virus (HSV) or varicella zoster virus (VZV)
   • Fungal keratitis: Commonly caused by Fusarium or Candida species
   • Parasitic keratitis: Most commonly Acanthamoeba
   • Non-infectious keratitis: Can be related to autoimmune conditions, dry eye, or exposure

Risk Factors

Contact Lens-Related Risk Factors

• Overnight wear
• Extended wear beyond FDA-approved schedule
• Poor lens hygiene
• Contaminated lens solutions
• Swimming or showering while wearing lenses
• Sharing lenses
• Using damaged lenses 1

Other Risk Factors

• Trauma or corneal injury
• Previous ocular surgery
• Tear film deficiencies
• Eyelid abnormalities
• Immunosuppression
• Diabetes mellitus
• Vitamin A deficiency
• Use of certain medications (topical NSAIDs, anesthetics, corticosteroids)
• Neurotrophic keratopathy 1

Clinical Presentation

Patients with keratitis typically present with:

• Eye pain (often severe)
• Redness
• Photophobia (light sensitivity)
• Tearing
• Blurred vision
• Discharge
• Corneal infiltrates or ulceration
• Anterior chamber inflammation 1

Diagnosis

Diagnosis of keratitis involves:

1. Detailed history: Including contact lens use, trauma, previous eye conditions
2. Visual acuity assessment
3. Slit-lamp examination: To identify corneal infiltrates, ulceration, and anterior chamber reaction
4. Microbiological testing: Corneal scrapings for culture and sensitivity when infection is suspected
5. Additional diagnostic tools: In vivo confocal microscopy, PCR tests for specific pathogens 2

Complications

If untreated or inadequately treated, keratitis can lead to:

• Corneal scarring
• Visual impairment
• Corneal perforation
• Endophthalmitis (intraocular infection)
• Loss of the eye 1

Treatment

Treatment depends on the cause but generally includes:

1. For bacterial keratitis:

   • Topical broad-spectrum antibiotics (fluoroquinolones or fortified antibiotics)
   • Cycloplegic agents to reduce pain and prevent synechiae formation
   • Consideration of topical corticosteroids after 24-48 hours if responding to therapy 1

2. For viral keratitis:

   • Antiviral medications
   • Possible corticosteroids depending on the layer affected 2

3. For fungal keratitis:

   • Topical antifungal agents (natamycin for filamentous fungi)

4. For Acanthamoeba keratitis:

   • Polyhexamethylene biguanide or chlorhexidine

Prevention

Prevention strategies include:

• Proper contact lens hygiene
• Avoiding trauma to the eye
• Prompt treatment of ocular surface diseases
• Regular eye examinations
• Avoiding sharing of eye makeup or contact lenses 1

Early recognition and treatment are crucial, as bacterial keratitis can progress rapidly with complete corneal destruction occurring within 24-48 hours 3. Patients with symptoms of keratitis should seek immediate ophthalmologic care to prevent vision loss.