Retinitis pigmentosa (RP) is an inherited eye condition that affects the photoreceptor cells responsible for capturing images from the visual field. These cells line the back of the eye in the region known as the retina.
People with RP experience a gradual decline in their vision because the two types of photoreceptor cells – rod and cone cells – die. Rod cells are present throughout the retina, except for the very centre, and they help with low light and peripheral vision. Cone cells are also present throughout the retina, but are concentrated in the central region of the retina (the macula). They are useful for seeing detail and for colour vision. In RP, the rod cells, and then eventually the cone cells, stop working, causing vision loss; however, many people with RP retain useful central vision well into middle age.
Rod cells are usually initially involved, and difficulty seeing in dim light, including transitioning from light to dark and vice versa, is one of the earliest symptoms. Peripheral vision will also decline, resulting in a narrowing of the visual field. Central vision is often maintained until much later.
RP is typically diagnosed in young adulthood, but the age of onset may range from childhood to the 40s or 50s. The condition is slowly degenerative, but the rate of progression and degree of visual loss varies from person to person and even among affected members of the same family. It is therefore very difficult to predict what an individual’s vision will be like at a specific time in the future. Both eyes are usually affected in a similar way.
RP is one of the most complicated genetic conditions, and over 80 causative genes have been identified to date (September 2019); faults in any one of these can cause the disease. RP follows various inheritance patterns, including autosomal dominant, autosomal recessive and X-linked. It is not unusual for cases to occur where there is no family history of the disease. More information about inheritance patterns is available from Unlock Genetics: www.RetinaUK.org.uk/about-inherited-sight-loss/genetics-and-retinal-health/.
There are currently no treatments that can effectively slow or stop the progression of RP (September 2019), although research in this area has accelerated and potential therapies are at the clinical trial stage.
Many of the novel treatments being tested are gene therapies or other molecular approaches that are specific to a particular genetic fault. It is extremely important that those affected by RP are offered genetic testing to allow them to access future treatments and clinical trials.
Despite the lack of current treatments for RP, it is still very important to continue to have regular eye check-ups. In particular, people with RP tend to develop cataracts at an earlier age than the non-RP population and can benefit from cataract surgery, although the visual outcome obviously depends on the severity of the retinal degeneration.
Information on current clinical trials can be found at www.clinicaltrials.gov; you can also read about possible treatment approaches for retinal disease at https://retinauk.org.uk/research/approaches-to-treatment/.
Retina UK is occasionally approached by researchers and companies looking for our help in recruiting participants for studies or patient involvement initiatives, and we can pass on details of opportunities to people on our database who have expressed an interest in these activities and given their consent to be contacted. Anyone who is not already in contact with Retina UK can call 01280 821334 or email info@RetinaUK.org.uk so that we can add them to our database. It is helpful for us to have as much detail about the diagnosis as possible, including genetic diagnosis if available, as some opportunities are condition specific.
The Retina UK Helpline provides information, support and signposting to people affected by inherited sight loss as well as healthcare and education professionals.
Contact 0300 111 4000 (9.30am – 9.30pm Mon to Fri) or Helpline@RetinaUK.org.uk.
More information for professionals can be found on the Gene.Vision website: https://gene.vision/knowledge-base/retinitis-pigmentosa-for-doctors/.