A 45-year-old, otherwise healthy, male presented with sudden loss of vision in the right eye one month after an attack of herpes zoster ophthalmicus. He had dark pigmented patches on the right half of the forehead in the region of frontal branch of the ophthalmic division of the trigeminal nerve (Figure 1).

His best-corrected visual acuity was 6/6 in the left eye and perception of light with accurate projection in the right eye. Ocular examination revealed normal ocular movements in both eyes. There was anisocoria with the right pupil being larger than the left. There was a relative afferent pupillary defect present in the right eye. The rest of the anterior segment including corneal sensations was normal in both eyes. Fundus examination of right eye showed blurred disc margins, splinter haemorhages over the disc, peripapillary oedema, oedematous macula, dilated and tortuous vessels, deep and superficial haemorrhages in all the four quadrants (Figure 2). Fundus examination of left eye was normal (Figure 3). The general physical and neurological evaluations were unremarkable. Patient was advised to get all the investigations for immune-compromised state, but he did not come back for follow-up.

Investigations to rule out immune-compromised status and orbital magnetic resonance imaging to confirm the diagnosis are the priority investigations.

Acyclovir has been the drug of choice in the therapy of herpes zoster infection. The recommended dosage for Acyclovir is 5–10 mg/kg administered intravenously every 8 h. The concomitant use of corticosteroid and an antiviral, though not contraindicated in an immunocompetent patient, remains controversial in consideration of the balance between the benefits of anti-inflammation and neuroprotection, on the one hand, and the hazards of further suppression of host immunity, on the other hand.^8,9

Thus, in a patient with the optic neuropathy of herpes zoster ophthalmicus we suggest the use of oral steroid under the cover of simultaneous intravenous acyclovir treatment. Untreated optic neuritis leads to optic atrophy and total loss of vision.

We conclude from this case study that early referral of all patients with herpes zoster ophthalmicus to the nearest eye centre is vital. Lid oedema may deter the primary care giver from diagnosing optic neuritis. We recommond that the treating physician should be aware of all the potential vision-threatening complications, which if not detected early and promptly treated, may lead to total loss of vision.

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