Usher syndrome is the most common condition that affects both hearing and vision. The major symptoms of Usher syndrome are hearing loss and an eye disorder called retinitis pigmentosa. Retinitis pigmentosa causes night-blindness and a loss of peripheral vision (side vision) through the progressive degeneration of the retina. As retinitis pigmentosa progresses, the field of vision narrows — a condition known as “tunnel vision” — until only central vision remains. Many people with Usher syndrome also have severe balance problems.
Approximately 3-6% of all children who are deaf and another 3-6% of children who are hard-of-hearing have Usher syndrome. Usher syndrome is inherited, which means it is passed from parents to their children through genes. Usher syndrome is an autosomal recessive trait. Usually, parents who have normal hearing and vision do not know if they are carriers of an Usher syndrome gene mutation. Currently, it is not possible to determine whether a person who does not have a family history of Usher syndrome is a carrier.
Because Usher syndrome affects hearing, balance, and vision, diagnosis of the disorder usually includes the evaluation of all three senses. Evaluation of the eyes may include a visual field test to measure a person’s peripheral vision, an electroretinogram (ERG) to measure the electrical response of the eye’s light-sensitive cells, and a retinal examination to observe the retina and other structures in the back of the eye. A hearing (audiologic) evaluation measures how load sounds at a range of frequencies need to be before a person can hear them. An electronystagmogram (ENG) measures involuntary eye movements that could signify a balance problem. Early diagnosis of Usher syndrome is very important. The earlier that parents know if their child has Usher syndrome, the sooner that child can begin special educational training programs to manage the loss of hearing and vision.
Currently, there is no cure for Usher syndrome. The best treatment involves early identification so that educational programs can begin as soon as possible. The exact nature of these programs will depend on the severity of the hearing and vision loss as well as the age and abilities of the person. Typically, treatment will include hearing aids, assistive listening devices, cochlear implants, or other communication methods such as American Sign Language, orientation and mobility training, and communication services and independent-living training that may include Braille instruction, low-vision services, or auditory training.
Some ophthalmologists believe that a high dose of vitamin A palmitate may slow, but not halt, the progression of retinitis pigmentosa. Researchers recommend that most adult patients with the common forms of retinitis pigmentosa take a daily supplement of 15,000 IU (international units) of vitamin A in the palmitate form under the supervision of their eye care professional. People who are considering taking vitamin A should discuss this treatment option with their health care provider before proceeding. Other guidelines regarding this treatment option include:
- Do not substitute vitamin A palmitate with a beta-carotene supplement.
- Do not take vitamin A supplements greater than the recommended dose of 15,000 IU or modify your diet to select foods with high levels of vitamin A.
- Women who are considering pregnancy should stop taking the high-dose supplement of vitamin A three months before trying to conceive due to the increased risk of birth defects.
- Women who are pregnant should stop taking the high-dose supplement of vitamin A due to the increased risk of birth defects.
In addition, according to the same study, people with retinitis pigmentosa should avoid using supplements of more than 400 IU of vitamin E per day.