Tens of thousands of elderly people are left struggling to see because of an NHS cost-cutting drive that relies on them dying before they can qualify for cataract surgery, senior doctors say.

The NHS has ignored instructions to end cataract treatment rationing in defiance of official guidance two years ago, a survey by the Royal College of Ophthalmologists has found.

The college said that refusal to fund surgery was "insulting" and called into question the entire system through which the NHS approves treatments. The comments came after guidance that said removing cataracts was almost always a good use of resources, and could even save money by preventing older people from falling, was largely ignored.

Cataracts cause blurry vision and removing them is one of the most common NHS procedures, with more than 400,000 carried out each year. In 2017 the National Institute for Health and Care Excellence (Nice) concluded that there was no justification for policies that denied patients cataract removal surgery until they could barely see.

A college survey at that time found that 66 per cent of eye units had such rationing policies. The college has repeated the survey and found 62 per cent of units retain policies that require people's vision to have deteriorated below a certain point before surgery is funded. Of the 59 units that replied to both surveys, only four have removed restrictions - and two have introduced fresh rationing.

"Nothing has changed," Mike Burdon, president of the college, said. "We can't have a situation where Nice is set up to make these decisions and [local health groups] simply say 'we don't like the answer' and deprive the elderly population of the chance of a better quality of life. I'm bitterly disappointed."

Mr Burdon, who also chaired the development of the Nice guidance, said that cataract surgery was "unbelievably cost effective" and there was no valid reason to restrict it.

"I think this has to be a money-saving exercise otherwise why do it? Even that is flawed because even if someone does not meet the threshold at 70, by 75 you will exceed the threshold. The only way they can save money is by hoping some people die between first noticing they have cataracts and deteriorating below the eligibility criteria."

He described cataract surgery as "probably the most life-transforming procedure the NHS does", citing patients who said they would rather be dead than blind. He added that bosses who imposed rationing policies should "sign up to apply the same conditions when it's their time to have a cataract. They are being unfair to the elderly population of this country."

A spokesman for Nice acknowledged that it might be difficult to implement the guidance quickly but insisted: "We still believe that cataract surgery is one of the ways in which the NHS can transform our lives. . . We share the college's concern that patients may be unable to access services they need, and welcome the attention that the college has brought to this issue."

Helen Lee, of the Royal National Institute of Blind People, said: "Cataracts can have a dramatic impact on someone's ability to lead a full and independent life, potentially stopping them from driving and increasing their chance of serious injury by falling. The Nice guidelines are in place for very good reason and make it clear that cataract surgery is highly cost effective and should not be rationed. It is nonsensical for clinical commissioning groups to deny patients this crucial treatment."

However, Julie Wood, chief executive of NHS Clinical Commissioners, which represents local funding bodies, defended the restrictions, saying: "Nice guidance is not mandatory and clinical commissioners must have the freedom to make clinically led decisions that are in the best interests of both individual patients and their wider local populations."

She added: "The NHS does not have unlimited resources. Ensuring patients get the best possible care against a backdrop of spiralling demands, competing priorities and increasing financial pressures is one of the biggest issues clinical commissioners face."