Including Retinitis Pigmentosa and Stargardt Disease
Inherited Retinal Disorders (IRDs) are the second commonest cause of severe visual impairment in childhood and the number one cause in the working-age population.
There are more than 400 different genetic causes of inherited retinal disorders, which makes accurate diagnosis and management challenging. Two of the most common conditions are Retinitis Pigmentosa and Stargardt Disease.
A group of conditions, which result in the gradual degeneration of the light sensitive cells of the retina. The retina is the light sensitive tissue inside the eye in which the first stages of seeing take place. For those not familiar with the structure of the eye, think of it as an old-fashioned camera that has a lens at the front, this lens focuses light onto a light sensitive film inside the camera.
In a similar way, the eye is a sphere, with a lens at the front which focuses light onto a light sensitive tissue; this tissue is called the retina, a multi-layered delicate structure. Over time the retina stops working and dies away.
The lens at the front of the eye is normally completely transparent but can become opaque with age, but often far earlier in inherited retinal disorders (IRDs), resulting in blurred vision – for which there is effective treatment.
Another complication of IRDs is the development of macular oedema (fluid at the central retina (macula)), which can cause blurred and occasionally distorted vision. There are multiple treatments that can be employed.
Also known as Stargardt macular dystrophy is the most common inherited macular dystrophy (affecting approximately 1 in 10,000 people) – the macula being the central part of the retina that is specialised for detailed vision and colour vision.
Most people with Stargardt disease have slowly progressive central visual loss that begins in their early teens. Stargardt disease may also appear in adult life when the visual loss may be milder. It has been recently recognised that Stargardt Disease may also present in later adulthood, and can be misdiagnosed as Age-Related Macular Degeneration.
Retinitis pigmentosa (RP) and Leber Congenital Amaurosis (LCA) are also known as rod-cone dystrophies.
RP is the most common inherited retinal disorder (IRD), affecting approximately 1 in 2,000 to 3,000 people. LCA is one of the most severe IRDs, causing severe visual impairment from birth or early childhood. There are an ever increasing number of clinical trials investigating treatments for both RP and LCA, including gene therapy. The first gene therapy has been recently approved for a specific genetic form of LCA (LCA caused by RPE65) – highlighting the critical importance of genetic testing.Professor Michaelides is a world expert in IRDs and their associated clinical trials. For further information, please see Clinical Trials and Research.
The symptoms are variable but usually begin in childhood or early adulthood; although less frequently can start in later life.
In one type of early-onset retinitis pigmentosa (RP), Leber congenital amaurosis, children are severely visually impaired at birth or in early infancy. By contrast, other types of RP may only show symptoms late in life.
In the more common types, such as RP, the patient will notice visual problems at dusk or in poor light, so-called night blindness, and also a gradual reduction in the peripheral field of vision, loss of the outer edges of vision (‘side vision’), resulting in a tendency to miss things or trip over things. At an early stage the central vision (‘straight-ahead and reading vision’) is unaffected. As the outer edges of the field of vision gradually disappear, the RP sufferer is left with the condition commonly referred to as ‘tunnel vision’. a lot of people maintain this central tunnel of useful vision until quite late in life, and manage to keep recognizing faces and other activities like reading and driving. The rate of loss of central vision is slower than that of peripheral visual field loss, but is highly variable. Detailed examination and imaging can help determine the rate of change and allow informed advice on prognosis.
Talk with Prof Michel if you have any of these symptoms right away here
There are effective treatments for complications of IRDs, including cataract and macular oedema. Supportive measures, such as provision of low vision aids and assistive technologies can also be very helpful indeed.
The majority of Inherited Retinal Disorders currently have no cure. However, there are an ever increasing number of clinical trials investigating treatments, including gene and stem cell therapy, aiming to enable vision to be restored or its loss to be slowed down. The first gene therapy has been recently approved for a specific genetic form of LCA (LCA caused by RPE65) – highlighting the critical importance of genetic testing.Professor Michaelides is a world expert in IRDs and their associated clinical trials. For further information please see Clinical Trials and Research.
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