Type 1 is the most severe form of the three, it profoundly affects hearing and balance since birth, with sight being affected during late childhood. Types 1 and 3 cause big balance problems due to vestibular dysfunction.

Type 2 has a slower progression, and people who suffer from it lose their sense of hearing and their sight later in life.

Usher Syndrome is the most frequent cause of deaf-blindness in children. It accounts for between 3 and 6% of all child deafness. 50% of deaf-blind people in first-world countries suffer from this syndrome. Its estimated prevalence is around 6-17/100,000.

Usher Syndrome is a rare disease first described in 1958.

• Congenital bilateral profound deafness: children are born with profound deafness. Cochlear implants are a solution for these children to have access to hearing and verbal communication
• Rapid vision loss: the speed of deterioration of the retina in Type 1 cases will start showing before the child reaches puberty. It causes nocturnal blindness during the first stages of the disease (around the age of 5) followed by the loss of daytime peripheral vision due to Retinitis Pigmentosa (RP).
• Abnormalities of the vestibular system: children affected by Type 1 (and 50% of Type 3) suffer from absence of balance because the semicircular canals in the inner ear have been affected. This leads to a delay in the beginning of the sitting position, the beginning of walking and in all the children’s physical activities (jumping, running, playing…), and affects mobility for the rest of their lives. The lack of balance can be compensated by different inputs: vision and proprioception (contact of the body with surfaces). As visual acuity decreases due to the progression of Retinitis Pigmentosa, balance problems increase.