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Discovery gives new insights into sight loss after stroke

Scientists at the University of Aberdeen have developed a medical device that appears to help stroke victims with partial sight loss regain some vision.

Every year some 55,000 people across Europe suffer partial loss of vision following a stroke. Around the same number of stroke sufferers in America are also affected.

The condition is called cortical blindness – this is blindness due to loss or injury to the visual pathways in the brain. Therefore the vision is affected while the eye itself appears to be normal.

Some limited recovery may occur for stroke sufferers with visual defects within the first few weeks after stroke, but the remaining visual deficits after this initial period are permanent. The standard clinical advice in the UK up until now has been that nothing can be done for this. This loss of vision interferes with everyday activities, such as reading, watching TV and getting out and about independently.

However, research based at the University of Aberdeen, has demonstrated that a medical device developed for stimulation of the blind field - the area of vision where there has been sight loss - shows real potential for patients in this predicament.

Their device was installed in the homes of 12 stroke patients with partial sight loss and each patient was asked to repeatedly perform a series of tasks over a three month period.

The scientists discovered that by the end of the process all 12 showed increased visual sensitivity within their blind field.

Dr Arash Sahraie, Reader in Visual Neuroscience, within the University of Aberdeen’s School of Psychology, led the research. He said: “We are very excited about this finding. It could give hope to the thousands of patients who have suffered sight loss following brain damage and are told on a daily basis that nothing can be done.

“Obviously these are very encouraging findings and we need to do a lot more research with many more patients but if we can help regain visual capability in the blind field it could have real benefits for people in this situation. For example, we are already finding that patients report that they can navigate more easily around their home or feel more confident when they are crossing the road.”

The researchers believe that the particular visual targets used in their device, optimally stimulate the surviving neuronal pathways which in turn encourage changes within the brain.

Dr Sahraie added: “You can get physiotherapy and speech therapy after brain damage so why not rehabilitation for the sight.”

Dr Mary Joan Macleod, Stroke Consultant at Aberdeen Royal Infirmary, said “If you are otherwise reasonably fit, but suddenly struggling because of your sight, it can be devastating for both you and your family. This offers a real opportunity to improve life for patients who have had this kind of stroke, where before we had little to offer these people.”

The research was supported by a grant from the Chief Scientists’ Office.

Picture shows an example of an image as seen by a stroke sufferer with partial sight loss


Notes to Editors

Issued by the Communications Team, Office of External Affairs, University of Aberdeen, King's College, Aberdeen. Tel: (01224) 272014.

Issued on: Tuesday 26th of September 2006

Ref: 2061cortical
Contact: Jennifer Phillips

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