He was a "fussy eater", but otherwise well. Initial tests indicated macrocytic anemia deficiency and low vitamin B12 levels, which were treated with vitamin B12 infusions and dietary guidance.
However, improving his diet proved hard.
A year later, he developed hearing loss and, soon after, began complaining he was having problems seeing. Sufferers become sensitive to the taste, texture, smell and appearance of certain types of food. "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", said Dr. Denize Atan, according to a report in the Annals of Internal Medicine journal.
When he was 17, the boy, who has not been identified, was seen by specialists at Bristol Eye Hospital because of his deteriorating sight.
"That means he can't drive and would find it really hard to read, watch TV or discern faces", said Dr Atan.
"He can walk around on his own though because he has got peripheral vision".
He was also found to have a condition called nutritional optic neuropathy (NON) - usually seen countries where access to food is restricted. It's potentially reversible, if caught early.
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"His parents had tried everything they could. but he would not eat anything else so they felt they had no choice but to buy him chips".
He developed the eating disorder at the age of 10 or 11 and it was only when he experienced problems with tiredness at 14 that he saw his GP.
He added added: "When this behaviour starts as a child it tends to continue as an adult".
The woman, who asked not to be named, said: "The first we knew about it was when he began coming home from primary school with his packed lunch untouched".
The body's cells need a variety of nutrients to function normally.
"[His initial doctors] said it was all in his head".
The problem with nerve cells in the optic nerve is that they can't fix or regenerate, she said, so any nerve loss is permanent.
"He followed that diet for a number of years".
"Fussy eating that is restricted to junk foods and causes multiple nutritional deficiencies is an eating disorder". The University of Bristol researchers who examined the case recommend clinicians consider nutritional optic neuropathy in any patients with unexplained vision symptoms and poor diet, regardless of BMI, to avoid permanent vision loss. His teachers became concerned too.