Herpetic Eye Disease: HSV & HZO

Two herpesvirus ocular presentations, both needing urgent ophthalmology referral. See bacterial-keratitis.md for the broader infectious keratitis differential (bacterial vs fungal vs HSV can look similar on slit lamp).

Herpes simplex keratitis

Herpes simplex keratitis is the most common ocular manifestation of HSV.

Clinical features: presents as a painful, watering red eye with visual disturbance. Three patterns:

• Epithelial keratitis — dendritic or geographic ulcer
• Stromal keratitis
• Endotheliitis

Fluorescein staining identifies the corneal ulcer in epithelial keratitis; a slit lamp examination is needed to differentiate the other two patterns.

Investigations: corneal swab PCR for HSV.

Management:

• Urgent referral to ophthalmology to confirm the diagnosis and commence treatment
• Aciclovir 3% eye ointment, 5 times daily for 10–14 days

Herpes zoster ophthalmicus

Shingles (varicella zoster reactivation) affecting the eye when the nasociliary branch of the trigeminal nerve (V1) is involved. More common with increasing age.

History and examination:

• The rash usually affects the tip of the nose (Hutchinson’s sign — a vesicle here predicts a higher risk of ocular involvement)
• Ocular complications: conjunctivitis, uveitis, keratitis, glaucoma
• Symptoms: red eye, visual loss, photophobia

Investigations: PCR of a vesicle confirms the diagnosis but should not delay treatment.

Management:

• Consult an ophthalmologist in all cases of HZO — even without obvious ocular signs at presentation, given the delayed/varied ocular complication pattern
• Topical aciclovir has no role in treatment
• Oral antiviral: valaciclovir 1 g orally, 8-hourly for 7 days (started within 72 hours of rash onset gives the best chance of preventing ocular complications)