Herpetic Eye Disease

Herpes simplex keratitis

• dsDNA virus

  • HSV1: airborne
  • HSV2: sexually transmitted
  • Ascends the sensory nerve axon to reside in the trigeminal ganglion

• Ocular involvement: blepharoconjunctivitis, keratitis (epithelial, stromal, endothelial, neurotrophic), uveitis, retinitis, bacterial superinfection

  • Primary infection in childhood commonly manifests with blepharoconjunctivitis, malaise, periorbital vesicular rash and preauricular lymphadenopathy

Epithelial keratitis

• FB sensation, pain, blurred vision, lacrimation
• Superficial punctate keratitis progresses to stellate erosion then to dendritic ulcer with terminal bulbs
• Ulcer base stains with fluorescein, margins and terminal bulbs stain with Rose Bengal
• Reduced corneal sensation
• Patchy iris atrophy

Tests

• Conjunctival and corneal swabs
• Scrapes: Giemsa stain shows multinuclear giant cells
  • Histopathology shows intranuclear inclusion bodies (Lipschutz bodies or Cowdy type A inclusions, also seen in VZV infection)

Management

• Topical antiviral
• Cycloplegia
• Oral antivirals in recurrent attacks

Stromal keratitis

• Multiple diffuse opacities
• Corneal vascularisation (‘interstitial keratitis’)
• Lipid exudation
• Scarring
• Thinning
• Anterior chamber activity, possibly raised intraocular pressure

Management

• Topical steroids: defer until the epithelium is intact. Use minimum effective dose
• Systemic antivirals: associated with reduced risk of recurrence
• Cycloplegia
• Monitor/treat IOP
• Surgery: gluing, tectonic graft, DALK, or PK (less desirable)

Disciform keratitis (endotheliitis)

• Possibly viral antigen hypersensitivity rather than reactivation

• Typically painless

• Blurred vision

• Haloes

• Central/paracentral disc of corneal oedema

• Descemet’s folds

• Mild AC activity may be chronic

  • Focal KPs: Wessley’s ring
  • Mutton fat KPs

• Raised IOP

Tests

• Consider AC tap for PCR if atypical presentation or no previous history of herpetic disease

Management

• Topical steroids: defer until epithelium intact and use minimum effective dose
• Preservative free treatments
• Systemic antivirals: continued prophylactically
• Cycloplegia
• Monitor and treat IOP

Other manifestations

• Geographic ulcer: in immunocompromised, or those given inappropriate steroids
• Metaherpetic ulcer: no live virus, but failure of epithelial healing
• Drug toxicity, neurotrophic cornea, low-grade inflammation

Differences between HSV and VZV

• Zoster

  • Demographic:

    • Elderly
    • Immunosuppressed

  • Dermatome

    • Complete

  • More painful and more likely to develop post-herpetic neuralgia

  • Nummular stromal infiltrates (coin shaped)

  • Raised plaque-like lesions stain with Rose-Bengal

  • Mucous epithelial plaques

  • Sectoral iris atrophy

  • No terminal bulbs

• HSV

  • Incomplete dermatome
  • Patchy iris atrophy
  • Terminal bulbs

Herpes Zoster Ophthalmicus (HZO)

• Tzanck smear: an easy test but not sensitive

  • Involves de-roofing vesicular lesions and spreading fluid on a slide followed by Giemsa staining to look for multinucleated giant cells

• Direct fluorescent antibody and PCR of corneal scrapes or vesicular fluid is highly sensitive and specific

• However the diagnosis is clinical and antivirals should be started for those where clinical suspicion is high

HZO risk factors

• Immunosuppression: chronic illness, drugs, HIV
• Age (>60)
• Caucasian (4 times more likely than Afro-Caribbean)

Neurotrophic ulcers

• Round ulcers with heaped-up elevated edges
• Typically inferonasal location due to Bell’s reflex
• Most common causes
  • HSV/VZV
  • Aneurysms
  • Stroke
  • Vn palsy
  • Diabetes
  • MS
  • Leprosy
  • Topical medication toxicity
  • Tumours: acoustic neuroma, angioma, neurofibroma