A Pox On Your Eye

Herpes zoster ophthalmicus

History:

• pain, paraesthesias, and skin rash in the V1 dermatomal distribution — what is the duration?
• May be preceded by headache, fever, malaise, blurred vision, eye pain, and red eye.
• postherpetic neuralgia occurs late.
• intercurrent stressors or immunosuppression? Consider the possibility of HIV/AIDS, especially in patients <40 years-old.
• Past history of chickenpox (can be subclinical)?

Examination:

• Observation — vesicular rash in the V1 distribution (classically unilateral, respecting the midline and does not involve the lower eyelid), pain may precede the onset of the rash. Look for Hutchinson sign. Less commonly the V2 and V3 distributions may also be involved.
• Visual acuity — usually normal, may be reduced.
• Corneal sensation — may be absent
• Extra-ocular eye movements — cranial nerve palsies can be present.
• Tonometry — IOP can be raised
• Slit lamp — check for conjunctivitis, corneal involvement (superficial punctate keratopathy, dendritiform lesions, keratitis), uveitis with an AC reaction, and scleritis.
  Corneal involvement may occur weeks or months after the rash and last for years. Sometimes it precedes the rash, or the rash may not even appear.
• Funduscopy — optic neuritis, retinitis and choroiditis can occur. Progressive outer retinal necrosis (PORN!) can occur in the immunocompromised.

Hutchinson sign is present if the vesicular rash extends to the tip of the nose. This corresponds to the distribution of the nasociliary branch of V1 and predicts higher risk of ocular involvement.

Antiviral therapy:

• Effective if started within 72 hours of onset of symptoms (but should be considered in almost all cases of zoster ophthalmicus):
  aciclovir 800 mg (child: 20 mg/kg up to 800 mg) po, 5 times daily for 7 days
• or valaciclovir 1 g po, q8h for 7 days
• or famciclovir 250 mg po, q8h for 7 days (500 mg, for 10 days if immunocompromised)
• Note: aciclovir is preferred in children and in pregnancy, seek expert advice
• if severe (orbital, optic nerve or cranial nerve involvement) or the patient is systemically ill hospitalize and treat with acyclovir 10 mg/kg IV q8h for 5 to 10 days.
• systemic antivirals can be supplemented with aciclovir 3% eye ointment, 5 times daily

Analgesia:

• Oral analgesia — IV analgeisa may be required; pain can be severe in the first 2 weeks.
• Postherpetic neuralgia — consider starting amitriptyline (e.g. 25 mg po tds) or gabapentin.

Skin lesions:

• Bacitracin or erythromycin ointment to the skin lesions bd
• Warm compresses to periocular skin tds

Fluorescein uptake on the cornea consistent with zoster ophthalmicus and dendriform keratitis.

If there is ocular involvement the patient requires an ophthalmology referral and close follow up.

Ocular involvement requires management by an ophthalmologist, and may include:

• Cool compresses and erythromycin ointment to the eye bd for conjunctival involvement; increase to 4-8 times a day for neurotrophic keratitis (send bacterial swabs) — surgery may be required for persistent corneal ulcers.
• Lubrication with artificial tears for corneal involvement
• Topical steroids (prescribed by an ophthalmologist) for keratitis and uveitis.
• Aqueous suppressants for raised intraocular pressure (see acute glacoma) and treat scleritis.
• Systemic steroids and high dose IV antivirals for retinitis, choroiditis, optic neuritis, and cranial nerve palsies
• Intraocular antivirials for acute retinal necrosis or progressive outer retinal necrosis (PORN) in consultation with Infectious Disease specialists.

Without treatment severe ophthalmitis and permanent visual loss may occur.

Remember that ocular involvement may occur in the absence of a rash, or days to weeks after the onset of the rash. Patients without ocular involvement should be advised to seek medical attention if they develop new ocular symptoms or signs.

• Ehlers JP, Shah CP, Fenton GL, Hoskins EN. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease Lippincott Williams & Wilkins
• NSW Statewide Opthalmology Service. Eye Emergency Manual — An illustrated Guide. [Free PDF]