A man in his early 40s was referred to our hospital with a complaint of decreased visual acuity in the right eye and orbital pain. He was undergoing treatment for glaucoma with visual field defects, including central areas. Upon initial visit, the right eye visual acuity was 0.07 and a rela tive afferent pupillary defect (RAPD) was detected in the right eye. Dilated fundus exam revealed optic disc swelling in the right eye. Goldmann perimetry showed upper visual field defects and a central scotoma. Brain contrast magnetic resonance imaging (MRI) showed enhanced right optic nerve. As optic neuritis was highly suspected, steroid pulse therapy was administered; however, visual acuity and optic disc swelling remained unchanged after treatment.
Leber hereditary optic neuropathy (LHON) was suspected and blood tests revealed a m.11778G>A point mutation. After 1 year, the fellow eye showed visual acuity loss without MRI enhancement on the optic nerve; therefore, LHON was diagnosed.
This report describes a case of LHON that mimics the clinical presentation of optic neuritis due to positive RAPD, orbital pain, and MRI findings.
LHON should be considered as a differential diagnosis even in cases suspected as optic neuritis due to MRI enhancement.
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