Late Onset Optic Neuropathy in Methylmalonic and Propionic Acidemia

PurposeTo describe 3 cases of late-onset bilateral optic neuropathy with visual dysfunction in patients with organic acidemia.DesignRetrospective case series.MethodsA total of 3 subjects, a 16-year-old male with methylmalonic acidemia (MMA), a 21-year-old male with MMA, and a 20-year-old female with propionic acidemia (PA), are included in this series. Comparison of the patients' clinical course, ophthalmologic exam, and testing are discussed. The outcome measures include visual acuity (VA), fundus appearance, visual fields, brain imaging, and genetic testing.ResultsAll 3 subjects had late-onset severe bilateral VA loss with bilateral optic nerve pallor, central or cecocentral scotomas on visual field testing, and negative diagnostic workups for other causes of bilateral optic neuropathy.ConclusionsPatients with organic acidemia may develop late-onset bilateral optic neuropathy with visual dysfunction despite lifelong propiogenic amino acid restriction and dietary supplementation.