How does it feel to open your eyes and see again after years, or even decades, of being blind? That was the experience of Steven Howarth, who yesterday said it felt like "a big burden lifted" after a pioneering operation at Moorfields Eye Hospital to treat a genetic condition brought stunning improvements to his vision. Howarth, 18, managed to stride confidently through a dimly lit maze to test his sight - having previously banged into its walls every time he tried it - after surgery to repair a degenerative eye condition.

Vicki Duncan, 29, understands Howarth's delight at being able to see his way around again. Like him, she was born with a retinal degenerative condition and, like him, she went on to have sight-saving treatment that gave her back more vision than doctors thought possible.

"I found out about my problem when I was about eight," she says. "What happens with the condition I've got is that there are excessive blood vessels in the eye, and these eventually cause the retina to detach. The retina in my left eye detached, and though I had surgery to reattach it, that didn't work. So from the age of nine I had no sight in my left eye, and though the vision in my right eye was OK, it wasn't great.

"But when I was 15, the sight in my right eye got very misty and hazy, and I realised that I was losing my vision in that eye too. Tests showed I had a cataract and the doctors thought it wasn't a good idea to operate. My vision gradually faded through my teens and early 20s, until I could only just make out the difference between light and dark."

But by the time Duncan was 26, techniques had improved and her consultant suggested that they should go ahead with an operation. "By that stage, I didn't have much to lose," she says.

On the day after her surgery, Duncan's bandages were "rather dramatically" removed. It was an extraordinary moment. "I had barely been able to see whether it was light or not, and now the light was suddenly so bright that I couldn't even keep my eyes open," she remembers. "For those first few days, I could only open them for a few seconds at a time before I had to close them again. It was such a shock."

She recalls sitting in her chair in the clinic that day and seeing, as she opened her eyes fleetingly, a pair of legs walking past. "It was amazing," she says. "I hadn't seen anyone's legs for years. It made me feel a bit weak, a bit dizzy."

Over the next few days and weeks there were many moments of revelation - one of the greatest of which came when she realised that she could see the face of her husband Kelvin for the first time. "I went up really close to him and I could make out his features. It was quite emotional. We were standing there and I was able to see him for the first time in our life together."

Using glasses or contact lenses, as she was able to do over the following weeks, even more of the world became visible. There were some surprises, she remembers. "Seeing my brother for the first time in more than a decade was strange. The last time I'd seen him, he was a typical adolescent, aged about 17. Now he was a man! And there was my dad too, who was, of course, older. And even though my mum had died when I was 14, I was able to look at photos of her and that was very special too."

The hardest thing of all, though, was seeing herself. "It took me a long time to build up the courage to do that. In my head I still looked like a teenager, and I knew seeing my mid-20s self was going to be shocking at some level. When I finally did look at myself in the mirror it felt weird - I kept going back to see myself again and again."

The practical fallout of having her sight restored has been huge. "I now work at the Royal National Institute of Blind People's head office, on their advice line, and I'd never have had the confidence to do this job before my operation," she says. "I live in Kent, so to commute into central London I have a 45-minute train journey followed by a 20-minute tube ride in the rush hour. It's possible now, but it wouldn't have been before."

There are other changes, too. "Kelvin is partially sighted as well, but before my operation he had better sight than me so he used to read to me. Now I read to him - it's strange." She also feels a lot more confident about her clothes. "I was always very interested in how I looked, and I used to get people to describe clothes to me very carefully before I bought them. But I used to avoid patterns because it's so difficult to describe a pattern to someone. Now, though, I wear them because I can both see the patterns on the hangers in the shops, and I can see myself in the mirror once the outfit is on. It's very different. And at work, I use a computer with a magnified type program - before, I had to use a program with speech software."

Hearing restoration through cochlear implants can bring a similar transformation in the life of someone who has had to live without one of their senses. Martine Laverty, 22, had her operation in August 2005. A month later, the electronic device that had been implanted into her ear to help her hear was switched on, again with startling results.

"It wasn't pleasant at all," Laverty remembers. "I was expecting to hear like I had done with my hearing aids, but everything sounded very fuzzy and abnormal. But the sounds started coming through with greater clarity over time.

"I'd only had access to low frequency sounds with my hearing aids, but now I can hear conversations and listen to the radio. Using the phone is something I've been able to do recently for the first time. It's not perfect - I feel a bit like a foreigner in the hearing world. But I am getting used to it. Although I've never found rustling paper so annoying, and I can tell you that birds singing isn't that fantastic.

"All I wanted from the implant was to make conversations easier," she says. "I had great difficulty hearing people and lipreading was tiring. Now I can relax more when having conversations. I don't need to look at people's lips so much, so I can look at their faces and pick up on what's being said. The implant isn't perfect, but it's made life quite a lot easier."

· For more information on the RNIB contact rnib.org.uk; helpline 0845 7669999. For more information about RNID, or to become a member, visit: rnid.org.uk or contact RNID's Information Line on 0808 808 0123 (freephone) or 0808 808 9000 (textphone).