Eye doctors in Bristol, UK, treated a 17-year-old after his vision had deteriorated to the point of blindness, BBC News reports.
Since leaving elementary school, the teen had eaten only French fries, Pringles and white bread, along with the occasional slice of ham or a sausage.
The boy, who cannot be named, had gone to his doctor at the age of 14 feeling tired and unwell, and was diagnosed with vitamin B12 deficiency. He was put on supplements, but he did not stick with the treatment or improve his diet.
Three years later, he was taken to the Bristol Eye Hospital because of progressive sight loss, according to the Annals of Internal Medicine.
Dr. Denize Atan, the specialist who treated him at the hospital, told the BBC: "His diet was essentially a portion of chips from the local fish and chip shop every day. He also used to snack on crisps - Pringles - and sometimes slices of white bread and occasional slices of ham, and not really any fruit and vegetables."
Dr Atan and her colleagues rechecked the young man's vitamin levels and found he was low in B12 as well as some other important vitamins and minerals - copper, selenium and vitamin D.
Tests revealed he had severe vitamin deficiencies and malnutrition damage. His blindness was caused by nutritional optic neuropathy, which is treatable if diagnosed early. But if it is left too long, the nerve fibers in the optic nerve die and the damage becomes permanent.
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