Introduction: Leber's optic neuropathy is a hereditary disease that mainly affects young males and is produced by specific mutations of the mitochondrial DNA, which affect the complex I of the mitochondrial respiratory chain.
Case report: An 18-year-old male who presented with a 3-week history of progressive loss of sight in the right eye. Magnetic resonance imaging of the brain revealed numerous hyperintense lesions in the periventricular and subcortical white matter, and the visual evoked potentials showed bilateral optic neuropathy that was mild on the left side and severe on the right side. A spinal tap was performed and oligoclonal bands were detected in the cerebrospinal fluid. In the weeks that followed vision continued to get worse on both sides and the patient had hyalinised vessels in the papilla, with lower amplitude responses bilaterally in the electroretinogram. A genetic study was conducted that revealed a primary mutation 11778 in gene MTND4 and secondary mutation 15257 in gene MTCYB, which were compatible with a diagnosis of Leber's optic neuropathy.
Conclusions: The absence of inflammation of the optic disc, which could lead to the suspicion of a retrobulbar neuritis, must act as a warning to the physician that he or she is possibly before a case of Leber's optic neuropathy, especially when the loss of vision is still progressing, when there is early bilateral involvement or if there is a family history of optic neuritis or multiple sclerosis.