What causes inherited retinal disease?
Inherited retinal diseases are genetic conditions caused by a mistake in one or more genes. Currently there are approximately 250 genes known to cause inherited retinal diseases. There are many more genes, however these are currently unknown and yet to be discovered. Some gene mutations that cause inherited retinal diseases are more severe than others.
With an inherited retinal disease, cells in the retina do not work correctly. The retina is the light-sensitive tissue at the back of the eye that sends information to the brain through the optic nerve, enabling people to see.
What are the symptoms of an inherited retinal disease?
Some people with inherited retinal disease experience a gradual loss of vision, which may eventually lead to complete blindness. Others can be born with vision loss or experience it in early childhood. How much sight a person loses relates to their age of onset. Typically, children suffer the worst impacts of inherited retinal diseases, with some paediatric patients going almost completely blind. Teenagers might have a gradual loss of central vision, while adults can lose patches of central vision.
Symptoms of inherited retinal disease might include: difficulty seeing in dark environments or in bright light, impaired peripheral vision, reduced central vision, not seeing colours or recognising differences between certain colours.
How is an inherited retinal disease diagnosed?
As well as noting patient and family history, ophthalmologists undertake clinical eye examinations that are generally non-invasive.
They will also engage in eye image analysis to measure retinal images to determine the rates of disease progression, and genetic analysis involving genetic testing to diagnose the cause of loss of sight in a patient.
Genetic testing is a type of medical test that identifies changes in chromosomes, genes or proteins. The results of a genetic test confirm or rule out a suspected genetic condition or help determine a person’s chance of developing or passing on a genetic disorder.
Genetic counselling might be recommended, in order to help patients understand the condition and what it might mean for families and individuals.
How are inherited retinal diseases treated?
There is no cure for most inherited retinal diseases, as too little is known about the genetic basis for these diseases. However, therapies such as gene therapy can be used to control the progress of disease. A crucial early step is to collect information from patients, for example analysing their genes and the changes in their eyes using advanced imaging techniques.
Researchers and clinicians are continually exploring gene therapies, stem cell technology and drug treatments that might prevent, slow or stop the damage that leads to vision loss and blindness.
Gene therapy aims to correct or compensate for the faulty gene. It might replace the faulty gene or add a new gene.
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