Half of patients left with complications from cataract operations carried out by Vanguard for Musgrove Park hospital in Taunton

Dozens of people have been left with impaired vision, pain and discomfort after undergoing operations provided by a private healthcare company at an NHS hospital.

One 84-year-old man claimed he has lost his sight and his family is calling for a full independent inquiry after it emerged that half of the 60 patients who underwent surgery suffered complications.

The routine cataract operations were carried out by the private provider in May to help to reduce a backlog at Musgrove Park hospital in Taunton, Somerset. But the hospital's contract with Vanguard Healthcare was terminated only four days after 30 patients, most elderly and some frail, reported complications, including blurred vision, pain and swelling. Some of those who suffered complications, including the 84-year-old man, have contacted lawyers to discuss seeking compensation, which raises the prospect of an NHS hospital picking up the bill for procedures done by a private health company.

The trust refused to talk in detail about what happened pending the conclusion of its own investigation. It also refused to discuss who would pick up any bill for compensation or details of its contract with Vanguard.

But, when the problems surfaced, a senior member of staff at Musgrove Park appeared to concede that the hospital would be liable for any payments. Dr Colin Close, Musgrove Park's medical director, acknowledged compensation claims could be made and was quoted in a local paper saying: "Any financial responsibility would rest with us."

The hospital now claims that Close was misquoted.

The son of the 84-year-old patient, who asked not to be named, said his father was referred for the cataract surgery by his GP. The retired salesman, from the Somerset Levels, did not consider he needed the operation but agreed to the treatment.

The son said the procedure took 15 minutes and his father felt it was "very rushed". The man suffers from mild dementia but the family said staff told his wife she could not be present as space was limited.

After the operation the man's vision was impaired. He thought it would return and went home but Musgrove Park contacted him to say there had been "complications" and he should return to hospital. He had another operation but his family said he had been told only a cornea transplant would restore his sight.

"My father is traumatised and depressed with the loss of his eyesight. Previous pleasures of gardening and watching sport on the TV have been taken away from him. This could have been prevented if the welfare of the patients had been thought about, rather than this urgency of getting people through," the man's son said.

Among the questions the family want addressed in an independent inquiry is whether Vanguard was brought in to save the trust from paying a financial penalty because of the backlog. They also want to know exactly when the hospital was made aware there was a problem.

Laurence Vick, a medical negligence lawyer who has been approached by some of the victims, said the case highlighted the "uneasy relationship" between the NHS and the private sector.

He said the question of who paid when outsourced NHS treatment failed was of growing importance as more services were handed over to the private sector.

Vick, the head of the clinical negligence team at Michelmores solicitors in Exeter, said: "We don't know what arrangements are in place for Musgrove to recoup their outlay and losses on this contract from Vanguard. From the taxpayer's point of view, it would be totally unreasonable for Vanguard to walk away from this scandal with only their reputation, and not their investment, damaged.

"The failings at Musgrove Park have once again uncovered the uneasy relationship between the NHS and the private sector, and it is crucial that an episode of this kind is not dismissed as an anomaly – a hybridised, public-private NHS will need to be wary of similar issues in future."

Musgrove Park approached Vanguard to help clear a backlog of cataract procedures. Vanguard surgeons began work at the start of May in a mobile unit. But patients quickly reported problems and the procedures were halted.

Musgrove Park said: "Due to the ongoing nature of our investigations it would be inappropriate for us to comment on the sequence of events surrounding the unfortunate complications experienced by our patients receiving cataract surgery with Vanguard Healthcare in their mobile theatre onsite at Musgrove Park hospital.

"Our first and foremost concern has always been our patients, and particularly those who have experienced complications. We have been in very close contact with them since the incident to ensure they are fully informed with our progress and receive the highest quality aftercare and treatment. We will want to discuss the outcomes of our investigations with them first, once they have reached conclusion."

Ian Gillespie, chief executive of Vanguard Healthcare Solutions, said: "Patient care is our number one priority and we're working closely with the trust to understand and fully investigate the root causes of any complications.

"This investigation is still ongoing, making it inappropriate to comment on specific issues or on individual patient cases. Operations were carried out in Vanguard's operating theatre by highly qualified surgeons, approved by the hospital, and with many years' experience of working in the NHS."

Gillespie said Vanguard was not conducting the same procedures elsewhere in the UK, he added.

Who is Vanguard Healthcare?

Founded in 1999, Vanguard boasts that it has the single largest fleet of mobile surgical facilities in the world. It has 40 such units with which it serves the NHS and other healthcare providers.

Surgery and endoscopy services, complete with equipment and staff if required, are carried out in the facilities, allowing hospitals across the UK to address temporary fluctuations in demand or capacity.

The Vanguard website claims that almost 195,000 procedures have been performed in its facilities and that 100% of its customers surveyed last year said they would use its services again.

It says it is the only provider of temporary mobile/modular healthcare solutions to be registered with the Care Quality Commission (CQC), the independent regulator of health and social care services in England. Last year, the CQC said Vanguard had met all required standards, observing: "Care and treatment were planned and delivered in a way that was intended to ensure people's safety and welfare."

Haroon Siddique