AD is a relatively new service, having been in existence in the UK for little more than ten years. It certainly has come a long way in a short time, with over three hundred DVDs that now come with a descriptive track, including the vast majority of new releases.

A comprehensive list of such DVDs can be found on the RNIB's website and they can be purchased from all good retailers. Service providers such as Sky and Virgin also provide AD for a wide range of programmes from soaps to the latest movies. Around ten percent of programmes come with AD per channel.

Sport has been rather slow to catch on to the idea of AD, but progress is being made particularly in football. Grounds have been providing commentary for supporters with sight problems for a number of years, most notably the FA Cup final in 2006 was supplied with the service. Still, the introduction of AD to the terraces hasn't exactly been free from problems.

Many clubs used Infra Red headsets that were offten effected by weather conditions particularly strong sunlight. Some radio headsets were used but these too had their drawbacks. Many such sets only had a limited range so supporters needing AD would have to sit together regardless of whether they were a home or away fan. This was a significant problem when developing the new Wembley stadium.

The designers eventually settled on the RAD system. Essentially, RAD are private radio frequencies designed just for the transmission of AD. A supporter will be given a small radio receiver and an earpiece through which they will be able to hear a second by second description of what's happening on the pitch. The commentary is provided by a professional describer who will be present at the ground.

Previously headsets were simply tuned to the local radio station. This was abandoned due to the fact that stations rarely concentrate on one match, often pausing for traffic updates or to cover other games. What's more, details of the prematch programme can be sent via the earpiece, whereas before this was impossible. Unlike the previous headsets, the fact that there is only one earpiece means that fans won't miss out on the atmosphere of the crowd whilst still being able to know what's going on.

AD is not confined to the premier league clubs, some non league sides are also using the RAD system. Cricket and rugby clubs are also providing AD. There are plans to set up a similar system for sight impaired people attending gigs and other live events.

Infra Red headsets are extensively used in both the theatre and cinema where they aren't subject to the same problems as open air events. The basic principle is the same in the cinema or the theatre. Through the headset the person will receive a commentary on what's happening on stage or on screen. Theatre goers with sight problems can also request an audio coppy of the programme, which will be played through the headset before the performance.

The only notable difference is that, like in sport, the theatre assisted performance is live. A trained describer who has seen the show on several occasions will tell the person exactly what happens as it is happening. Most theatres attempt to have at least two performances with AD per play run.

In the cinema, with so many showings a day, live AD would be impractical so the commentary is prerecorded and delivered along with the film. There is a wide selection of films in the cinema that come with AD, ranging from blockbusters to low budget flicks. In fact, Britain is now leading the field in terms of AD.

By way of contrast, countries such as Australia are lacking decent facilities. Australian cinemas don't have AD and its use on TV and DVD is limited, only around 5% of DVDs are given a descriptive track.