Deafblindness, sometimes called dual sensory impairment, is the combination of both hearing and vision impairment. Most people with deafblindness have some residual hearing and/or sight and a wide range of forms of deafblindness exist. There are many causes of deafblindness; congenital deafblindness is when someone is born with combined sight and hearing difficulties and acquired deafblindness is when someone loses hearing or sight, later in life. It is useful to identify two distinct cultural groups within the deafblind community. The first group are born blind and lose their hearing as adults. They tend to continue to use speech as their main communication and have a variety of hearing devices to enable them to communicate. The second group are born deaf and lose their sight as adults. This group are culturally deaf and use sign language to communicate. A significant community of deafblind people have a genetic condition called Usher Syndrome. They are born deaf and develop Retinitis Pigmentosa (tunnel vision) when they are adults.