Key points from article :
Teenager developed permanent sight loss after living on a diet of chips and crisps.
Tests revealed he had severe vitamin deficiencies and malnutrition damage.
Teenagers diet was essentially a portion of chips from the local fish and chip shop every day.
He was put on vitamin supplements and referred to a dietitian and a specialist mental health team.
Nutritional optic neuropathy - the condition the young man has - is treatable if diagnosed early.
The study was published in Annals of Internal Medicine journal.
