People with a rare eye disease known as retinitis pigmentosa (RP) suffer a gradual loss of vision; some become completely blind. Now, an innovative new approach to treatment has given dozens of people the chance to see again. With the help of a retinal implant, special glasses and intensive training, people who were blind have a new way of viewing the world which could one day benefit people with other degenerative eye diseases.
We spoke to Professor Marie-Noelle Delyfer, University Hospital of Bordeaux, who has already performed eight such operations.
What is retinitis pigmentosa (RP) and what is the prognosis for patients?
RP is actually around 300 distinct genetic disorders that lead to the loss of photoreceptors on the retina. Some affected individuals have a reduction in their visual field while others become blind. With such a rare disease, it is difficult to describe a typical patient. Some lose their sight early in life or in early adulthood but there are others who become blind only in their 70s or 80s.
Until 20 years ago, there were no treatments at all and the disease was not well understood. The first genetic cause of the disease was identified in 1984 – before that it was thought of as an inflammatory disease.
What treatments are available?
Some pharmaceutical therapies help to maintain photoreceptors but this only slows the progression of the disease – it’s not a cure. In the longer-term, there is some research on gene therapy targeting the mutations responsible for RP.
How can technology help?
I have used a new technology, from SecondSight, with eight carefully selected patients living with end-stage RP. These patients have an electrode array implanted in their retina. They wear glasses that are fitted with a camera that ‘sees’ their surrounding environment. This signal is sent to the electrode in the eye which transmits a signal to the visual cortex.
More than 20 patients in France have had the operation. All patients have reported an improvement in vision. They don’t see exactly what people with normal vision can see, but the technology enables them to detect motion.
What is the ideal patient for this kind of treatment?
Patient selection is a big challenge. They must really be end-stage RP patients who saw before but did not lose vision until after the age of 10. They should also be older than 25 years and have an expectation of one year of life. The oldest patient to date is 73.
Prospective patients also undergo psychological evaluation to help us to understand what they expect from surgery and to check for other issues that might interfere with recovery and rehabilitation. For example, if they have depression or other issues this could be a challenge. And, because the surgery will change the way they relate to other people, we have to consider all the practical ways in which their lives with be changed.
How do patients prepare for surgery?
We provide CDs that detail what the patient should expect and then they can ask us questions. The surgery takes around three hours and is technically quite complex but, for the patient, it is usually possible to leave the day after surgery and they don’t suffer much discomfort. After taking tablets and eyedrops to help the healing process they begin a lengthy rehabilitation process.
Why is post-operative training so important?
Patients have to get used to the prosthesis and their visual cortex needs time to adapt to this new form of visual input. Training and rehab is a two-year process beginning at specialist centres with the remainder done at home. The content of the training programme can depend on the patient’s expectations – some want only to be able to walk around their houses; others want to be able to do specific tasks.
What impact can restoring patients’ sight have?
Without exception, all the patients have had an improvement in visual testing. They can move around their houses without injuring themselves; they can identify an object on a table; some can even read letters on a table top.
Looking ahead, what future developments do you foresee in this field?
There is a lot of work ongoing to refine the device and it could become possible to use it earlier in the disease. And, with very good results for patients with end-stage RP, there are now trials to test the device in end-stage AMD (age-related macular degeneration).
Normally, rare diseases like RP would not receive much attention but the possibility of ultimately helping thousands of people with AMD has made it more attractive. So everybody is winning – a number of RP patients are benefiting today and potentially improving the prospect of an innovative solution for AMD patients