The mother of a five-year-old boy who is almost blind in one eye claims a simple eye test could have saved his sight.

Lewis Cager was diagnosed ten months ago with a condition called isamatropic ambylopia, which meant the sight in his left eye had failed to develop properly, leaving it almost useless.

But his mother believes if his condition had been spotted a few years earlier it could have been treated and his sight could now be normal.

Lewis's mother, Tina, of Downs Valley Road, Woodingdean, is furious her son's vision will be impaired for life when she believes a test carried out routinely in other parts of the country could have prevented it.

Mrs Cager said: "In other regions of the country a compulsory check is done on all babies and, as a result, cases like Lewis are practically non-existent.

"It makes me furious to think this could have been prevented. The test is very simple and does not need specially-trained doctors or equipment.

"All they have to do is cover each of the child's eyes at a time then get them to pick something up. If they hesitate or can't do it they know there might be a problem."

Nobody knew about Lewis's sight problem until a school nurse at Woodingdean Primary School noticed he could not see out of his left eye during a heightened vision test.

He was referred to Sussex Eye Hospital where doctors confirmed Lewis had isamatropic ambylopia but it was too late to treat it effectively.

Mrs Cager said: "A doctor at the eye hospital said if Lewis had been given a proper examination when he was two or three they could have treated the problem.

"Because he was five by the time it was detected it was too late and there was not much they could do."

Doctors at Sussex Eye Hospital in Brighton gave Lewis strong glasses and a patch to wear over his good eye for ten hours a day in a last-ditch attempt to improve his sight but to no avail.

Mrs Cager said: "When we went back the consultant said there had been no improvement and there was no point in carrying on the treatment.

"There was nothing more they could do for him. Now he is going to have to live with impaired vision for the rest of his life.

"He will never be able to have any job in the services and his judgement of speed and distances will be impaired.

"He will probably always have to wear glasses and it can only get worse as he gets older."

Mrs Cager, 28, has complained to South Downs NHS Health Trust about the lack of testing for young children.

She wants eye tests to become compulsory for babies and toddlers so more children do not suffer in the way her son has.

A spokesman for the trust said she could not comment on Lewis's case because Mrs Cager's complaint was still under formal investigation.

Nobody at the trust was able to say if the trust carried out the eye tests on babies or had any plans to do so in the future.