Medical case narrative
Three boys losing their sight — B12 again
What happened
Three boys developed optic neuropathy — damage to the optic nerve threatening their vision — in the setting of vitamin B12 deficiency.
What it looked like
Vision loss in children, a symptom nobody files under "vitamin deficiency" until the labs come back.
What the labs found
B12 deficiency, identified through blood testing, as the driver of the optic nerve damage.
What changed
The original report's authors describe visual improvement in all three boys with treatment. One later systematic-review table codes the first boy as "no improvement," and this entry won't pretend that disagreement away — the honest version is: treated, with improvement reported by the treating team and disputed for one child by a later review.
The test that told the story
Serum vitamin B12.
Sources: Original case series and a later systematic review table.