The purpose of this investigation is to gain additional knowledge about what causes type 1 and type 2 Usher syndrome-inherited diseases that can cause balance problems and impaired hearing and vision-and to develop better diagnostic tests. Patients with type 1 Usher syndrome usually are deaf from birth and have speech and balance problems. Patients with type 2 disease generally are hearing impaired but have no balance problems. All patients develop eye problems that cause difficulty seeing in the dark.