• Video report by ITV News Science Editor Tom Clarke

The benefits of a cataract operation can be more than just clearer vision.

But like thousands of others, Barrie Hudson, only got the operation after screening proved his sight had deteriorated enough.

A cataract diagnosis - which means the lens of the eye has clouded over clouding over of the lens of the eye - means a person's sight gets steadily worse.

Cataract surgery is, in fact, the most common operation in the NHS - with over 400,000 carried out each year.

The cost of the operation can be little more than £700.

NICE, which makes recommendations to the NHS on the provision of healthcare, recommends diagnosed patients are operated on irrespective of the quality of their vision.

Yet thousands of patients, like Barrie, are being screened and not operated on.

Speaking to ITV News, Mr Hudson said after the "life changing" operation his vision "moved into focus". He now enjoys a far wider range of colours then ever before.

The benefits of a cataract operation aren't just for the patient, but also for the NHS. The cost of looking after a patient with cataracts is greater than the cost of patients having surgery.

40,000 cataract operations are carried out by the NHS every year. Credit: ITV News

But the NHS rejected almost 3,000 operations for cataract surgery in 2018/19 - twice the number two years ago.

Dr Michael Burdon of the Royal College of Ophthalmologists told ITV News: "Depriving people unnecessarily of their quality of life is completely unjustified."

As budgets are cut, screening goes up and surgery goes down. But the NHS says it has to manage priorities.

2,900 cataract operations were rejected by the NHS last year. Credit: ITV News

NHS Clinical Commissioner Dr Grahame Jackson told ITV News: "The local commissioners need to work the bets value for the pounds they have in their local community.

"That is providing cataract surgery as appropriate but it's also providing cancer services, accident and emergency services and a whole range of other issues as well."