Scientific Background


Approximately forty million people across the world suffer from blindness. This loss of vision is devastating and greatly reduces one’s autonomy and quality of life. Large economic losses to society are accrued due to reduced workforce participation and burden of care.

Causes of blindness

The underlying causes of blindness are diverse- from macular degeneration, cataracts, retinitis pigmentosa, and other eye-related diseases, to injury and damage to the eye and optic nerve, to cortical dysfunction. Nevertheless, patients with a damaged visual system can be broadly classified into two groups: those for whom the damage occurs somewhere along the visual processing pathway up to and including the photoreceptor layer in the retina; and those for whom damage occurs after this stage in visual processing.

Existing therapies

For the former group of patients, significant progress has been made towards solutions in the form of retinal prostheses, stem cell transplants, and gene therapy.

Unaddressed forms of blindness

However, these treatments only benefit patients in whom the retinal ganglion cells that connect the eye to the brain have been spared. For the large majority of patients whose sight cannot be restored via the retina, the long-held dream has been to restore visual function by interfacing directly with the visual cortex. NESTOR aims to develop a revolutionary method to control brain activity and restore visual function in blind people.

Our approach

In brief, electrodes are surgically inserted into the brain, and the application of electrical current to the electrodes results in electrical stimulation of the surrounding tissue. At each electrode, this electrical stimulation ‘artificially’ generates the perception of a small dot of light in the patient’s mind, which is termed a ‘phosphene.’

How do phosphenes look?

Individual phosphenes vary in terms of size, shape and colour, depending on which part of the visual cortex is being stimulated. However, they typically appear at specific locations in the visual field, depending on the site of microstimulation in the cortex.

Simple image creation

The reliable positioning of the phosphenes means that simple images can be created by selecting the appropriate subset of electrodes through which stimulation is delivered, from one moment to the next. This truly promising technique is known to be effective even in people who have been without sight for decades, providing them with assistive vision and enhancing their quality of life.

Existing limitations

Thus far, however, previous implants have provided assistive vision for no more than several months. Hence, several crucial technological advances are required before safe, permanent solution is available to patients. 

Our focus areas

Broadly speaking, our consortium works on these key scientific and technological research goals:

1) The development of a high-channel-count, biocompatible, chronically implantable neuronal interface for the visual cortex.

2) The wireless transfer of power and communications between the implant and the external equipment.

3) The generation of artificial visual percepts that are useful in everyday life, using video footage from a camera that is worn by the patient.

Future goals

Our ultimate vision is the creation of a clinical application of this technology in profoundly blind people, allowing them to use this simple form of artificial vision in everyday life.

The NESTOR consortium comprises the following research organisations:
The Netherlands Institute for Neuroscience, Maastricht University, Radboud University, and the University of Twente. © Copyright 2018 NESTOR. All Rights Reserved.