Clinicians in the UK are reporting a case of nutritional optic neuropathy (ON) in a 17-year-old boy as a result of a poor diet.
The teen presented to a neuro-ophthalmologist after two years of progressive vision loss. Body mass index was normal (22 kg/m2).
Findings were consistent with ON: visual acuity was 20/200 bilaterally, he read eight of 17 Ishihara colour plates with either eye, pupil responses and slit-lamp examination findings were normal and he had bilateral central visual field defects and loss of retinal nerve fibers affecting the optic discs temporally and maculopapillar bundles.
Except for delayed P100 responses in visual evoked potentials with normal amplitudes, a neurologic examination was normal. Genetic tests for Leber hereditary ON were negative.
Laboratory evaluation showed elevated homocysteine and methylmalonic acid levels, indicating functional vitamin B12 deficiency. This prompted further investigation of his nutrition.
The patient reported that from early childhood, he would not eat foods of certain textures. He had a daily portion of fries from the local fish and chip shop and snacked on crisps, white bread, processed ham slices and sausage.
He was prescribed nutritional supplements and was referred to mental health services for his eating disorder. His visual acuities stabilised but did not improve.