People with poor eyesight are being forced to wait almost six months for operations on the NHS to remove cataracts, official figures reveal.

Patients in Herefordshire are facing average delays of 168 days – five months and 17 days – for cataract surgery, according to data collected by NHS Digital, the health service’s statistical arm. Waiting times in Great Yarmouth and Waveney in Norfolk are the second worst in England at 163 days, while they now average 154 days in North Lincolnshire.

The revelations have sparked warnings that the mainly older people affected are being put at increased risk of a fall because their vision is so impaired while they wait, and also that too many clinical commissioning groups (CCGs) are restricting access to the operation in order to save money.

“It is shocking that patients are waiting months and on too many occasions being denied cataract surgery,” said Helen Lee, policy manager at the Royal National Institute of Blind People.

“It often results in people losing their independence and becoming depressed as they can no longer do ordinary things like drive, go out at night and see bus numbers. People are more at risk of falls, which can lead to hip fractures and hospitalisation, which can be devastating.”

She accused many local NHS bodies of defying guidance from the National Institute for Health and Care Excellence, which says that people with a cataract should be referred to have it removed promptly if it is giving them cloudy vision and affecting their quality of life. However, many CCGs are refusing to treat patients whose eyesight has not deteriorated enough in their judgement.

The number of cataract removals by the NHS has risen relentlessly over the past decade – from 284,897 in 2007-08 to 377,397 in 2017-18. The vast majority of those having surgery are aged 70 or over.

But the NHS Digital figures show that for many this is an achingly slow process. People in 17 CCG areas are having to wait at least four months on average for operations. In North Cumbria and Dudley, for example, the mean wait has reached four months and 28 days, while in Harrogate and Vale of York it is four months and 26 days.

In addition, waits for cataract removal have risen by as much as three months in some places since 2014, the data shows. Average waits in Great Yarmouth and Waveney CCG have more than doubled, from 71 days in 2014-15 to 163 days in April-October 2018, the last period for which figures are available. That is a rise of 92 days or 130%. Similarly, waits have worsened by 83 days over that time in Dudley, Vale of York and North Lincolnshire CCGs.

NHS Digital sets out the mean time in days that people have to wait in all 195 CCG areas. It does not give the longest delays endured by individual patients, which, in many cases, will be much longer than the average.

One patient had a cataract removed in Leeds from his left eye on 9 July after waiting close to the NHS’s 18-week (126 days) supposed maximum wait for non-urgent care. “It’s just been frustration after frustration for me, waiting for the surgery that I needed. I was on the point of going private because I was so frustrated at waiting so long to get it removed on the NHS,” he said.

He fell while waiting for the operation, injuring his hip. He also had to give up driving – “My car is my lifeline because I’m on my own” – after his eyesight deteriorated so much that he posed a risk behind the wheel. However, his sight in his left eye is now “fantastic” and he hopes to resume driving after the cataract in his right eye is removed.

Lengthening delays and the growing demand for cataract operations are forcing the NHS to send increasing numbers of patients to be treated privately. In 2013-14, it paid for independent providers to perform 41,860 cataract removals. That number had jumped to 75,005 by 2017-18 – a 79% rise over four years – separate NHS Digital figures reveal.

This means that almost one in five of the 377,397 NHS-funded cataract procedures in England that year were done in the private sector.Firms that have benefited from the NHS’s increasing inability to remove cataracts quickly enough include Ultralase, which runs 20 treatment centres in the UK. It promises to treat people within eight weeks. The growing number of cataract patients it is treating includes those who have been refused treatment by the NHS, a spokeswoman said.

A Department of Health and Social Care spokesperson said: “We expect all patients to have timely access to cataract surgery. Through our NHS long-term plan, we will boost the number of planned procedures and reduce waiting lists.”

• This article was amended on 21 July 2019 to remove some personal information.