A boy who refused to eat anything but chicken and chips has suffered devastating consequences.

Those of us with fussy kids always just assume they’ll get past it.

“So what if he only eats baked beans and bananas? It’s not like he’ll being doing that in ten years’ time.”

“Yeah he’ll only eat nuggets and chips but it’s just a phase.”

“Who has ever met an adult that just eats peanut butter sandwiches, don’t stress,” we tell ourselves.

Well if you are the mum of a fussy eater, like me, what you are about to read might just shake you up a little bit, because it turns out that when our own mums told us to ‘eat out veggies’ they might have actually been onto something.

A Perth mother whose son faced growing eye sight problems to the point of near blindness has been shocked to find out that what her son was suffering from was due to his diet.

Kerry Moore’s son, Cian, only ate potatoes, like chips, chicken, dry bread and coke since he was six years old. At around the age of 13 his vision began to fail. His eyes were gritty and irritated and blindness was encroaching.

Mrs Moore told Fairfax Media she tried ophthalmologists and paediatricians, a children's hospital and an adult hospital, light tests, genetic tests and various vision tests in trying to find the cause of her son's blindness, but there didn’t seem to be an explanation.

But as her son retreated to behind his computer she grew increasingly desperate and travelled to Sydney to see ophthalmologist Stephanie Watson.

"We were terrified that he was going to lose his sight," Ms Moore said. "It seemed to be getting worse."

What she thought was going to be a non-curable disease turned out to be something even more surprising.

A vitamin deficiency.

Professor Watson said she had seen the side effects of this type of malnourishment before – in Kenya – and the odd cases in Australia.

"It's associated with a bit of food faddiness where kids might not like food textures and tastes so they end up with this incredibly bland diet," Professor Watson, chair of the Royal Australian and New Zealand College of Ophthalmologists [RANZCO] public health committee told Fairfax Media.

"We need a certain amount of vitamin A and without it the cells don't mature normally.

"They don't become eye cells, they start going down another path like skin."

In two other cases she had dealt with, including a 52-year-old man with self-diagnosed food intolerance who had eaten only potatoes, white bread without butter or margarine and cola since he was a child developed tunnel vision and night blindness  - and a 12-year-old boy whose diet consisted of hot chips and nuggets whose vision became so poor he only had light perception in his right eye -  the outlook wasn't great.

So she started Cian on Vitamin A doses immediately.

Dr Nancy Copperman, director of public health initiatives for North Shore Long Island Jewish Health System in New York, told HealthPop that children go through picky food stages - called "food jags" - when they are four to six years old.

These so called “food jags” are when children might eat a particular food meal after meal - like peanut butter or just baked beans - and reject other foods, only to one day start eating a new food like white bread exclusively, repeating the behaviour.

Sound familiar?

Dr Nancy Copperman food jags are natural part of development and most children grow out of this stage of development.

But Cian Moore wasn't one of these kids.

His mother Kerry, who says she feels immense guilt at allowing her son’s diet to deteriorate for so many years has since pleaded for parents to persevere when it comes to their own children's eating habits.

“You know when you tell your kids to eat their vegetables....EAT YOUR VEGETABLES KIDS!!!" she wrote on Facebook.

Two years on from being diagnosed, and after being treated with vitamin shakes, Cian’s vision in his right eye has almost completely recovered, but sadly the damage to his left eye is permanent.

His mother says he has regained his friends, returned to football and most importantly  - now eats his veggies.