Adenoviral Keratitis: Causes, Effects on Vision, and Treatment
Introduction
Adenoviral keratitis is a viral infection of the cornea caused by adenoviruses, most commonly associated with epidemic keratoconjunctivitis (EKC). It is a highly contagious condition that can lead to corneal inflammation, opacity, and vision impairment in severe cases. While adenoviral conjunctivitis is self-limiting, adenoviral keratitis can persist for weeks to months and may cause long-term visual disturbances due to corneal involvement.
Causes and Transmission
Adenoviral keratitis is caused by adenovirus serotypes 8, 19, 37, and occasionally serotypes 3, 4, and 7. It spreads through:
• Direct contact with infected eye secretions.
• Contaminated surfaces (e.g., towels, medical instruments).
• Respiratory droplets in some cases.
The infection is highly contagious and can spread in healthcare settings, schools, and households.
Clinical Features of Adenoviral Keratitis
1. Stages of the Disease
Adenoviral keratitis occurs in three overlapping phases:
a. Acute Epithelial Keratitis (Days 1-7)
• Occurs in conjunction with epidemic keratoconjunctivitis (EKC).
• Symptoms:
• Red eye, tearing, foreign body sensation, photophobia.
• Watery discharge and conjunctival hyperemia.
• Periocular lymphadenopathy (preauricular lymph nodes swollen and tender).
• Slit-lamp examination:
• Superficial punctate keratitis (small epithelial defects).
• Corneal infiltrates begin to form.
b. Subepithelial Infiltrates (Days 7-21, Peak at 2-4 Weeks)
• Immune-mediated response to viral antigen deposition in the corneal stroma.
• Symptoms:
• Persistent photophobia and blurred vision.
• Glare sensitivity due to corneal opacity.
• Slit-lamp examination:
• Subepithelial infiltrates in the anterior stroma, leading to corneal haze.
c. Chronic Keratitis (Weeks to Months, Sometimes >1 Year)
• Persistent immune response leads to:
• Corneal scarring and haze, causing long-term visual impairment.
• Recurrence of infiltrates months later due to delayed immune activation.
Effects on Vision
Adenoviral keratitis can significantly affect vision due to:
1. Corneal Infiltrates & Scarring – Persistent haze reduces visual acuity and contrast sensitivity.
2. Irregular Astigmatism – Due to corneal surface disruption.
3. Photophobia & Glare – Light scattering from corneal opacities.
In mild cases, vision recovers within weeks to months. Severe cases may lead to permanent vision loss if corneal scarring persists.
Diagnosis of Adenoviral Keratitis
Diagnosis is primarily clinical, based on history, symptoms, and slit-lamp findings.
1. Slit-Lamp Examination
• Punctate epithelial erosions in early stages.
• Subepithelial infiltrates in later stages.
• No corneal ulceration or hypopyon (differentiates from bacterial keratitis).
2. Adenoviral Detection Tests (Optional, Confirmatory)
• Rapid Adenovirus Test (e.g., AdenoPlus®) – Detects viral antigens in eye swabs.
• PCR or Viral Culture – Used in severe or atypical cases.
3. Differential Diagnosis
• Herpes Simplex Keratitis (dendritic ulcers with fluorescein staining).
• Bacterial Keratitis (purulent discharge, stromal infiltration).
• Fungal or Acanthamoeba Keratitis (history of trauma, contact lens wear).
Treatment of Adenoviral Keratitis
There is no specific antiviral treatment for adenoviral keratitis, but supportive and anti-inflammatory therapies can help manage symptoms and prevent complications.
1. Supportive Therapy (For Acute Stage, Days 1-7)
• Lubricating Eye Drops (Artificial Tears) – Relieve irritation.
• Cold Compresses – Reduce inflammation and discomfort.
• Strict Hygiene Measures – Prevents spread (avoid sharing towels, handwashing).
2. Corticosteroids (For Subepithelial Infiltrates & Chronic Keratitis)
• Indicated when vision is significantly affected by corneal haze or infiltrates.
• Prednisolone acetate 1% or fluorometholone 0.1% (4 times/day, taper over weeks-months).
• Helps reduce inflammation but may prolong viral shedding, so used cautiously.
3. Topical Cyclosporine or Tacrolimus (Steroid-Sparing Agents)
• Used for recurrent infiltrates or steroid-dependent cases.
• Cyclosporine 0.05% (Restasis) or Tacrolimus 0.03% reduces immune response.
4. Antiviral Agents (Limited Role)
• Cidofovir (off-label topical use) has shown some benefit but is not widely used due to toxicity.
• No role for acyclovir, as adenovirus is not affected by herpes antivirals.
5. Phototherapeutic Keratectomy (PTK) for Severe Cases
• Used in refractory cases with significant corneal scarring.
• Excimer laser removes subepithelial infiltrates and scars to improve vision.
Prevention of Adenoviral Keratitis
Since adenoviral keratitis is highly contagious, prevention strategies are essential:
• Hand hygiene and disinfecting surfaces (especially in hospitals and clinics).
• Avoiding eye rubbing to reduce self-inoculation.
• Isolating affected individuals (no sharing of personal items).
• Proper disinfection of ophthalmic instruments in clinics.
Prognosis
• Mild cases resolve within 2-4 weeks with no long-term effects.
• Moderate cases (subepithelial infiltrates) can persist for weeks to months, requiring treatment.
• Severe cases with corneal scarring may result in permanent vision loss and require surgical intervention.
Early diagnosis and appropriate management improve outcomes and reduce long-term visual impairment.
Conclusion
Adenoviral keratitis is a contagious and potentially sight-threatening condition associated with epidemic keratoconjunctivitis (EKC). While self-limiting in mild cases, it can lead to chronic corneal inflammation, subepithelial infiltrates, and vision loss if untreated. Supportive care, corticosteroids, and immunomodulators play key roles in managing inflammation and preserving vision. Preventative measures, especially hygiene and infection control, are crucial in limiting outbreaks.