Zoster Ophthalmicus
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Direct answer
Zoster ophthalmicus is reactivation of varicella-zoster virus in the ophthalmic division of the trigeminal nerve, and it is the commonest cranial-dermatome zoster in adults. Vesicles on the tip of the nose (Hutchinson sign) indicate nasociliary nerve involvement and predict intraocular disease, so every such patient needs same-day ophthalmology referral. Treatment is oral aciclovir 800 mg five times daily (or valaciclovir 1 g three times daily) for 7–10 days, ideally started within 72 hours of rash onset.
What you must remember
- V1 dermatome: frontal branch most affected; vesicles do not cross the midline.
- Hutchinson sign — vesicles on the nasal tip, collarette or side — signals nasociliary (50% of the eye's sensory supply) involvement and roughly doubles the risk of ocular complications.
- Pseudodendrites of VZV keratitis stain poorly with fluorescein, are coarse, and lack the terminal bulbs of HSV dendrites — a favourite viva distinction.
- Complications: punctate keratitis, stromal keratitis, steroid-sensitive granulomatous iritis, episcleritis, sectoral iris atrophy, and late acute retinal necrosis.
- Oral antivirals work only early; late disease is managed by the ophthalmologist with topical steroids for immune-mediated keratitis and uveitis — never self-prescribe these.
- Post-herpetic neuralgia is the commonest chronic complication, rising steeply after age 50 years.
- An immunocompetent adult with zoster ophthalmicus should prompt consideration of HIV testing if risk factors exist, but routine screening is not mandated in Indian guidance.
How to work through an exam case
A 68-year-old man presents on day 2 of a painful right forehead rash with a few vesicles reaching the nasal tip and mild photophobia. Walk it through in order. First, confirm the dermatome: the rash stops at the midline and involves the forehead and upper lid, so this is V1 zoster, and the nasal tip involvement makes it zoster ophthalmicus rather than simple frontal zoster. Second, triage severity: ask about vision, photophobia and eye pain, because these suggest keratitis or iritis rather than just skin disease. Third, start the antiviral immediately — at 72 hours from rash onset the benefit of aciclovir 800 mg five times daily for 7–10 days is well established, and many clinicians treat beyond 72 hours while new vesicles are still forming. Fourth, refer the same day for slit-lamp examination with fluorescein; the pseudodendrite of VZV keratitis is the finding examiners quote. Fifth, plan follow-up at 7–10 days: if stromal haze or iritis has appeared, topical steroids under ophthalmic supervision are added while oral antivirals continue, since VZV ocular inflammation is largely immune-mediated. Finally, address analgesia for neuralgia early — gabapentin or pregabalin plus adequate non-opioid analgesia reduces the chance of entrenched post-herpetic neuralgia.
Where students slip
Two traps recur. The first is treating a red eye after zoster as bacterial conjunctivitis and prescribing antibiotic drops while the real process is granulomatous iritis or stromal keratitis; any anterior chamber inflammation, ciliary flush, or photophobia after V1 zoster is sight-threatening until an ophthalmologist says otherwise. The second trap is the Hutchinson sign itself — candidates quote it but cannot explain it, losing viva marks. The nasociliary nerve supplies the nasal tip and carries the same sensory fibres that serve much of the globe, so nasal-tip vesicles are a visible flag that the virus has travelled the branch most likely to reach the eye. Remember also that vesicles may appear before the eye becomes red, so a normal-looking eye on day 2 does not discharge the patient; it simply schedules the repeat review.
Frequently asked questions
Which antiviral and dose is standard for zoster ophthalmicus in an immunocompetent adult?
Oral aciclovir 800 mg five times daily for 7–10 days, or valaciclovir 1 g three times daily for 7 days, started within 72 hours of rash onset; famciclovir 500 mg three times daily is an alternative.
What is Hutchinson sign and why does it matter?
Vesicles on the tip or side of the nose, indicating nasociliary nerve involvement; it predicts a higher likelihood of ocular complications such as keratitis and uveitis and mandates urgent ophthalmology referral.
How do VZV pseudodendrites differ from HSV dendrites?
VZV lesions are coarse, plaque-like, stain poorly with fluorescein and lack terminal bulbs, whereas HSV dendrites are fine branching lesions with terminal bulbs that stain brightly.
When are topical steroids used in zoster ophthalmicus?
Only under ophthalmological supervision, for immune-mediated stromal keratitis and iritis after epithelial disease has healed; steroids given during active epithelial ulceration can worsen the infection.
Is intravenous aciclovir ever required?
Yes — for immunocompromised patients, sight-threatening disease, retinitis or acute retinal necrosis, where high vitreal drug levels are needed.