Recurrent Optic Neuritis as a Misleading Presentation of Leber Hereditary Optic Neuropathy: The Need for High Clinical Suspicion in Young Men.

A 29-year-old Chinese gentleman presented with acute-onset right eye (RE) central scotoma and blurring of vision. Upon presentation, RE visual acuity (VA) was 6/30. The RE optic disc (OD) was mildly swollen, but other findings were unremarkable. A computed tomography (CT) imaging study showed no evidence of a space-occupying lesion. The erythrocyte sedimentation rate (ESR) and other laboratory blood results were normal. The patient was empirically treated with a course of steroids for optic neuritis (ON), but no marked improvement was noticed. He presented again two months later with worsening visual problems in both eyes (BE). The right and left VA reduced to 6/36 and 6/18, respectively. BE OD appeared swollen and hyperemic. BE central scotoma was confirmed with the Humphrey Visual Field (HVF) test. A magnetic resonance imaging (MRI) study was conducted and only revealed a mild heterogenous hyperintensity of the right optic nerve. There is no other evidence of central nervous lesion suggestive of demyelinating disease. A blood investigation for Leber hereditary optic neuropathy (LHON) genetic testing was done, and a confirmatory result of mitochondrial DNA (mtDNA) G11778A pathogenic mutation was detected.