Case of the Month I May 2020

The patient likely had nutritional amblyopia, which is due to a deficiency of B-complex vitamins (particularly thiamine). It is characterized by temporal optic nerve pallor and cecocentral scotomas. By the time the patient had laboratory testing, he had taken B-complex vitamins for about one month. Laboratory testing revealed normal B12 and folate, moderately reduced vitamin B6, and elevated thiamine. There were elevated liver function tests. An MRI of the optic nerves and brain was unremarkable. Unfortunately, the vision did not improve after initiating vitamin supplementation.

There are other causes of cecocentral scotomas. Optic neuritis typically afflicts younger adults and can be bilateral. Our patient’s normal MRI argues against this diagnosis. There was peripheral neuropathy, but alcohol abuse could explain this problem. Another consideration is Leber's hereditary optic neuropathy, which has an onset in early adult and is more frequent in males (80-90%). There are several toxic optic neuropathies, including methanol, which typically causes more diffuse optic nerve damage. Anterior ischemic optic neuropathy usually results in superior or inferior disc pallor, and generally patients are older.