Herpes Zoster Ophthalmicus

Herpes zoster ophthalmicus (HZO), also known as ophthalmic zoster, is shingles involving the eye. Symptoms generally include a rash of the forehead with swelling of the eyelid. There may also be eye pain, eye redness, and light sensitivity. Before the rash appears tingling may occur in the forehead along with a fever. Complications may include vision loss, increased pressure within the eye, and chronic pain.

The underlying mechanism involves a reactivation of the varicella zoster virus within the ophthalmic nerve (the first division of the trigeminal nerve). Risk factors include poor immune function, psychological stress, and older age. Diagnosis is generally based on symptoms.

Treatment is generally with antiviral pills such as acyclovir. Steroid eye-drops and drops to dilate the pupil may also be used. The herpes zoster vaccine is recommended for prevention in those over the age of 50. Shingles affects up to half a million people in the United States a year of which 10% to 25% involve the eye.

Signs and symptoms

Skin

Trigeminal shingles with uveitis and keratitis

• Viral prodrome
• Preherpetic neuralgia
• Rash, transitioning from papules to vesicles to pustules to scabs. The frontal nerve is more commonly affected than the nasociliary nerve or lacrimal nerve.
• Hutchinson's sign: cutaneous involvement of the tip of the nose, indicating nasociliary nerve involvement. A positive Hutchinson's sign increases the likelihood of ocular complications associated with HZO.
• Disseminated distribution in individuals with immunodeficiency.

Cornea

Herpes zoster ophthalmicus as seen after florescence staining using cobalt blue light

• Epithelial: punctate epithelial erosions and pseudodendrites: often have anterior stromal infiltrates. Onset 2 to 3 days after the onset of the rash, resolving within 2–3 weeks. Common.
• Stromal:
  • Nummular keratitis: have anterior stromal granular deposits. Occurs within 10 days of onset of rash. Uncommon
  • Necrotising interstitial keratitis: Characterised by stromal infiltrates, corneal thinning and possibly perforation. Occurs between 3 months and several years after onset of rash. Rare.
• Disciform Keratitis (Disciform Endotheliitis): a disc of corneal oedema, folds in Descemet's membrane, mild inflammation evident within the anterior chamber and fine keratic precipitates. Chronic. Occurs between 3 months and several years after the onset of the rash. Uncommon.
• Neurotrophic: corneal nerve damage causes persistent epithelial defect, thinning and even perforation. Cornea becomes susceptible to bacterial and fungal keratitis. Chronic. Late onset. Uncommon.
• Mucous plaques: linear grey elevations loosely adherent to the underlying diseased epithelium/stroma. Chronic. Onset between 3 months and several years after the onset of the rash.

Uveal

Anterior uveitis develops in 40–50% of cases with HZO within 2 weeks of onset of the skin rashes. Typical HZO keratitis at least mild iritis, especially if Hutchinson's sign is positive for the presence of vesicles upon the tip of the nose.

Features:

This non-granulomatous iridocyclitis is associated with:

• Small keratic precipitates
• Mild aqueous flare
• Occasionally haemorrhagic hypopyon

HZO uveitis is associated with complications such as iris atrophy and secondary glaucoma are not uncommon. Complicated cataract may develop in the late stages of the disease.

Treatment

Treatment is usually with antivirals such as acyclovir or valacyclovir by mouth. There is uncertainty as to the difference in effect between these two antivirals. Antiviral eye drops have not been found to be useful. These medications work best if started within 3 days of the start of the rash.

Cycloplegics prevent synechiae from forming.