Herpetic Eye Disease
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Direct answer
Two viruses dominate viral eye disease in India: herpes simplex virus type 1 and varicella-zoster virus. Herpes simplex epithelial keratitis is the branching dendritic ulcer with terminal bulbs, pathognomonic on fluorescein staining, and it is treated with topical acyclovir 3 per cent or ganciclovir 0.15 per cent gel — never with topical steroids, which convert dendrites into large geographic ulcers. Steroids enter only in stromal and endothelial (disciform) disease, always with antiviral cover. Herpes zoster ophthalmicus follows the ophthalmic division of the trigeminal nerve; involvement of the nasal tip (Hutchinson sign) predicts ocular complications and mandates oral acyclovir 800 mg five times daily, started within 72 hours of the rash.
What you must remember
- Dendritic ulcer: a dichotomously branching epithelial lesion with terminal bulbous swellings, staining with fluorescein; pathognomonic of HSV epithelial keratitis; enlarged dendrites and multiple branching points mark it as active viral replication.
- Epithelial disease treatment: acyclovir 3 per cent eye ointment five times daily (or ganciclovir 0.15 per cent gel), with optional mechanical debridement; topical steroids are contraindicated; oral acyclovir supplements in frequent recurrences and in children.
- Disciform keratitis: endothelial inflammation with focal stromal oedema, Descemet folds and keratic precipitates beneath the oedema — an immune disease, treated with a tapering topical steroid plus antiviral cover.
- Necrotising stromal keratitis: severe autoimmune stromal inflammation with neovascularisation and scarring; systemic antiviral plus careful topical steroid; corneal thinning threatens perforation.
- Neurotrophic ulcer: corneal hypoesthesia after HSV leaves a persistent oval epithelial defect with rolled edges; manage with lubricants, bandage lens or tarsorrhaphy — not antivirals.
- Herpes zoster ophthalmicus: V1 dermatomal rash; Hutchinson sign (vesicles on the nasal tip, nasociliary nerve) warns of eye involvement; pseudodendrites are raised mucous plaques without terminal bulbs and stain poorly with fluorescein.
- Zoster complications: conjunctivitis, episcleritis and scleritis, keratitis, granulomatous iritis with secondary glaucoma, and post-herpetic neuralgia; oral acyclovir 800 mg five times daily for 7–10 days within 72 hours reduces ocular disease and neuralgia.
- Long-term suppressive acyclovir 400 mg twice daily is considered after frequent recurrent HSV keratitis or after corneal transplantation for herpetic scarring.
One virus, three corneal faces
Follow one patient to see why steroid timing decides outcomes. She presents with a dendrite — a branching fluorescein-staining epithelial ulcer with terminal bulbs. Active viral replication in epithelium: acyclovir ointment five times a day, and the dendrite heals in a week. Suppose instead she had used a steroid–antibiotic drop from a pharmacy first: the dendrite widens into a geographic ulcer with clumped borders, viral spread fuelled by suppressed immunity, and the cornea thins. Months later she returns with blurred vision and halos: a disc of stromal oedema with folds and keratic precipitates — disciform keratitis, an antigen–antibody response against residual viral antigen in endothelium. Now the treatment reverses: a topical steroid is essential to suppress the immune reaction, but only under acyclovir cover, tapered slowly over weeks; stopping abruptly invites relapse. The same patient, older and immunosuppressed, may one day develop shingles over the forehead and lid — where a rash reaching the nose tip (Hutchinson sign, via the nasociliary nerve) predicts keratitis and uveitis, and oral acyclovir within three days of the rash is the intervention that changes the disease.
Where students slip
The most tested error is the steroid in epithelial herpes — examiners build assertion–reason questions around it, and the reasoning is immunosuppression plus collagenase activation, not "allergy". The second slip is calling a zoster pseudodendrite a dendrite: the zoster lesion is a raised mucous plaque, stains poorly, has no terminal bulbs and does not respond to antivirals alone. A viva favourite asks which single sign at the nose predicts eye disease in zoster, and why — the nasociliary nerve supplies both the nasal tip and the globe.
Frequently asked questions
What is the treatment of dendritic HSV keratitis?
Topical acyclovir 3 per cent eye ointment five times daily or ganciclovir 0.15 per cent gel, with or without epithelial debridement; topical steroids are contraindicated because they enhance viral replication.
When are topical steroids justified in HSV keratitis?
In stromal immune disease and disciform (endothelial) keratitis, always with concurrent antiviral cover and slow tapering — never in active epithelial disease.
What is Hutchinson sign?
Vesicles on the tip of the nose in herpes zoster ophthalmicus, indicating nasociliary (and therefore ocular) involvement and a high likelihood of ocular complications.
How do zoster pseudodendrites differ from HSV dendrites?
Pseudodendrites are raised mucous plaques without terminal bulbs, stain poorly with fluorescein, are found in zoster, and represent sticky epithelium rather than active viral ulceration.
What is disciform keratitis?
A focal disc of stromal oedema with Descemet folds and keratic precipitates, an immune-mediated endothelialitis; treated with topical steroids under antiviral cover.
What dose of oral acyclovir is used in herpes zoster ophthalmicus?
800 mg five times daily for 7–10 days, ideally started within 72 hours of rash onset to curtail ocular complications and post-herpetic neuralgia.