Keratitis

Inflammation of the cornea

Clinical presentation

• Photophobia

• Severe ocular pain and associated foreign body sensation

• Hypopyon: aggregation of inflammatory cells within the anterior chamber resulting in visible 'sediment' in front of the eye inferiorly

Investigations

• Examination - anaethetics if photophobic, fluorescein, corneal reflex

• Corneal scrape for gram stain and culture
• In acanthamoeba ketatitis also culture contact lens

Bacterial Keratitis

Causative organisms

• Staphylococcus aureus

• Streptococcus pneumoniae

• Pseudomonas aeruginosa (strongly associated with contact lens use)

• Moraxella species

Clinical features

• Usually associated with other corneal pathology or contact lens wear

Management

• Chloramphenicol 1% ointment 3x1

• Erythromycin 0.5% ointment 4x1

• Ciprofloxacin 0.3% ointment 3x1

Viral Keratitis

Causative organism

• Herpes simplex virus (HSV) type 1

• Varicella-zoster virus (VZV)

Clinical features

• Very painful

• Can be recurrent

• Recurrences eventually result in reduced sensation

Management

• Acyclovir 3% eye ointment PID for 7 days

• Ganciclovir 0.15% eye gel PID

• Oral acyclovir
• HSV → 5x400mg for 7 days
• HZO → 5x800mg for 7-10 days

• DO NOT treat with steroids - can cause corneal melt and perforation of the cornea

Adenoviral Keratitis

Causative organism

• Adenovirus

Clinical features

• Bilateral

• Usually follows URTI/conjunctivitis

• May affect vision

Management

• Can require steroids to speed up recovery if becomes chronic
• Povidone iodine 1% + Dexamethasone 0.1%

Fungal Keratitis (Keratomycosis)

Causative organisms

• Filamentous fungi (most common in tropical and agricultural settings)
• Fusarium species
• Aspergillus species
• Curvularia species

• Yeasts (nonfilamentous)
• Candida species (more common in eyes with pre-existing ocular surface disease)

Clinical features

Symptoms

• Ocular pain (often less severe than bacterial keratitis in early stages)

• Redness

• Photophobia

• Blurred vision

• Tearing

• Foreign body sensation

Signs

• Gray-white or yellowish corneal infiltrate

• Dry, feathery margins of the ulcer

• Satellite lesions surrounding the primary infiltrate

• Elevated slough or plaque on the ulcer surface

• Stromal edema

• Hypopyon (often immobile)

• Minimal purulent discharge compared with bacterial keratitis

Investigations

• Corneal scraping for:
• Kalium hydroxide (KOH) 10% wet mount
• Gram stain
• Fungal culture (Sabouraud dextrose agar)

• Confocal microscopy (adjunctive, if available)

• PCR (where accessible)

Management

• Topical Antifungal Agents
• Natamycin 5% ED 1x/2 hr for 5-7 days: first-line for filamentous fungi
• Amphotericin B 1.5% ED 1x/hr: preferred for Candida
• Voriconazole 1%: broad-spectrum alternative

• Systemic Antifungals
• Oral voriconazole or itraconazole for deep stromal involvement or scleral extension

• Adjunctive Measures
• Cycloplegics for pain relief
• Avoid topical corticosteroids during active infection

Acanthamoeba Keratitis

Causative organism

• Acanthamoeba species (e.g., A. castellanii, A. polyphaga)

• Exists in two forms:
• Trophozoite (active, pathogenic)
• Cyst (dormant, highly resistant to treatment)

Clinical features

Symptoms

• Severe ocular pain, often out of proportion to clinical signs

• Red eye

• Photophobia

• Blurred vision

• Excessive tearing

• Foreign body sensation

Signs

• Early:
• Punctate epithelial erosions
• Pseudodendrites

• Intermediate:
• Radial perineural infiltrates (radial keratoneuritis)
• Anterior stromal infiltrates

• Late:
• Ring-shaped stromal infiltrate (classical but late finding)
• Stromal edema and thinning
• Hypopyon (variable)

• Reduced corneal sensation may occur

Management

• Topical Anti-Acanthamoebal Agents
• Biguanides:
• Polyhexamethylene biguanide (PHMB) 0.02%
• Chlorhexidine 0.02%
• Diamidines:
• Propamidine isethionate
• Hexamidine

• Adjunctive Therapy
• Cycloplegics for pain relief
• Oral analgesics
• Avoid topical corticosteroids in active infection (may worsen disease)