It is teatime in the Tibbetts household and four-year-old twins Callum and Ryan arrive home from school and sprint excitedly towards their smiling father, brandishing a stegosaurus jigsaw. Later, they will complete the puzzle and read together before he puts them to bed. While this is a normal routine for most families, for Ian Tibbetts it is tantamount to a complete miracle.
This time last year, the former factory worker from Telford in Shropshire, was facing the certainty of blindness. His sight was so bad that he had never seen his sons' faces. "They were just shapes. I couldn't make them out. I had to actually learn to tell them apart by their voices. I could tell whichever one it was by the way they spoke and sometimes by how quickly they moved," he now recalls.
But thanks to an extraordinary operation in which one of his teeth was implanted in his eye socket to act as a cradle for a false lens, the veil has been lifted on his life.
The extreme procedure, known as osteo-odonto-keratoprothsesis (OOKP) is carried out on just five patients with irreversible corneal scarring each year by the leading ophthalmic surgeon Professor Christopher Liu at the Sussex Eye Hospital in Brighton, Sussex. Because the tooth tissue is the patient's own, the body doesn't reject it. His extensive team is the only one of its kind in Britain and Professor Liu is engaged in a global teaching project to bring OOKP to other countries, particularly in the developing world where catastrophic eye injuries routinely result in lifelong blindness.
Ian's descent into darkness began more than two decades ago when he suffered an industrial accident. As he was removing a piece of scrap metal from an oven it struck him in the right eye, ripping his cornea in six places. The wound healed and he returned to work but a year later he began to suffer a series of recurrent eye problems.
Puzzled doctors treated him for a range of conditions including conjunctivitis, detached retina, corneal abscess and persistent infection, but he lost the sight in his right eye in 1998, followed a decade later by nearly all the remaining vision in his left.
More than 360,000 people are registered as visually impaired in England, with up to two million in the UK living with some form of impairment, the majority of them the result of ageing. The impact on an individual's life can be deeply traumatic, explains Professor Liu.
"Very often people's self-esteem and mood can be affected. They are not able to do the job they were doing. They can lose their friends and become dependent on other friends and family. There are hobbies they can no longer do. It is quite horrendous, really," he says.
Ian, 43, whose remarkable journey out of the shadows of blindness is charted in a BBC documentary broadcast next week, entitled The Day I Got my Sight Back, was no exception. Unable to work, he was forced to give up his interests in 3D model making and motorbikes and could barely make out his favourite team, Manchester United, on the television.
He was drinking heavily during the day and spending the remainder of his time in bed while his wife Alex, 35, worked and looked after the house. "Everything he liked to do was taken away," she says. Like all those who eventually undergo OOKP – some of whom have had up to 40 operations – he was at the end of the road. He had lost count of the procedures he had undergone and was advised to go home and prepare to go blind.
"I was told it was a waste of time me coming to the hospital because they couldn't do anything. They had tried every single thing they could think of and nothing worked," he said.
But Ian and his wife were not prepared to give up, especially as the couple planned to have a family. Ian was desperate to ensure that he would be able to see his children and watch them grow up. He contacted his local consultant after learning about advances in stem-cell technology and was told that while this did not offer hope at present, OOKP might, and he was referred to Professor Liu. "I would do anything to get some sight back. I had to try something. I said anything is better than what it was," he says. He was eventually called to attend a seminar in Brighton, where the procedure was explained in detail.The two-stage surgery involves the removal of a piece of tooth and bone from the patient's mouth, which is then cut down to shape and an optical cylinder inserted in a drilled hole.
This is then inserted in a pouch cut in the flesh under the non-operative eye, while a flap of skin is removed from the inside of the cheek and stitched on to the front of the eye due to receive the tooth.
Four months later, when the tooth has developed a blood supply, another operation is carried out to remove part of the cornea, the iris and the vitreous (the gel inside the eye), while the tooth and bone lamina is then cut out of the pouch and stitched into the eye socket, where it is covered by the piece of cheek skin.
"The technical success rate is close to 100 per cent. The number of people who will see well for a very long time is two-thirds to three-quarters. If I am a bit more pessimistic I will say half to two-thirds. But for the majority of people it will work," says Professor Liu.
But while there are obvious physical challenges, some of the greatest obstacles to success are mental. Potential patients, who may have seen nothing for decades, undergo psychological tests to assess whether they are robust enough to withstand the procedure and its stark cosmetic consequences.
They must also give up smoking. Professor Liu says they should be prepared for both the best- and worst-case scenarios. "If they have not seen for a long time they will see that people are older and the cars look different. If they have had an accident they will see their own scarring and injuries for the first time.
"If it doesn't work, it is a huge burden because patients – whatever you tell them – think it is the success rate rather than the failure rate that applies to them. It is rather like the lottery – you think you are going to win," he says.
Unfortunately for Ian, there was no miraculous moment of restored sight when his bandages were lifted last December – an experience explained by another patient as like being "lifted from the grave".
He recalled: "My chin just hit the floor. I went right on a downer. I thought that's it – it's going to bugger my Christmas up. It had already buggered the summer up and the boys' birthday. I was hoping to see for their birthday."
But slowly, like many other patients, a few weeks later when the stitches were removed, he began to be able to make out shapes, colours and movement. And then – finally – for the first time he could see Callum and Ryan.
"I had a picture in my head of what they looked like but they were better. I'm a bit biased there. The image in my mind was totally different to how they were – the features. I gave them a big hug and a kiss," he says.
Professor Liu said that the outcome is dependent on the degree of eye damage before OOKP, and that there can be future and unexpected setbacks. Yet Ian has no doubt that others in his position should have the operation. Professor Liu agreed. "It is always a joy, of course, that a patient can see," he said. However, his advice to all those he treats is the same: "Please enjoy every day you have your sight but plan your life as if your sight will last for ever," he adds.
'The Day I Got my Sight Back' will be broadcast on BBC One at 10.35pm on 8 October