Restoring vision to those who have lost it

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On April 11th, the Vision InstituteIn the context of clinical trials, Pixium Vision presented the progress of its work on the IRIS® retinal prosthesis, designed and developed by Pixium Vision: new perspectives that bring hope to thousands of visually impaired and blind people.

The World Health Organization (WHO) estimates that 285 million people worldwide are visually impaired (who may have low to moderate vision or severe visual impairment): 40 to 45 million of them are completely blind. 

Retinitis pigmentosa, choroideremia, these ophthalmological diseases with complex names have a fundamental point in common: they affect the retina and all attack the phororeceptors; their failure will progressively impair vision and often lead to profound visual impairment, even blindness, although their optic nerve is still functional.
Replacing photoreceptors by stimulating certain cells in the retina offers the hope of restoring, at least partially, the vision of patients and increasing their autonomy. This is the objective of the company Pixium vision, which is developing two vision restoration systems (IRIS and PRIMA) in Paris at the Institut de la Vision, a joint research structure of UPMC, Inserm and CNRS, headed by Professor José-Alain Sahel.

Retinal neuromodulation or how to re-stimulate retinal neuronal cells

The construction of the "Image" message can be likened to a two-step process: 
1. The light signal is first "integrated" by the photoreceptors (cones and rods) of the retina which will convert it into an electrical signal. 
2. This is then transmitted to the inner retina and then to the brain via the optic nerve to achieve effective image perception.

As the construction of the "image" message is divided into two main phases, it is possible to envisage treating these patients by stimulating the optic nerve with electrodes positioned on the retina. The use of retinal implants could eventually allow these patients to regain useful vision. 

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Neuromodulation consists of acting directly on nerves or on the target area where nerve activity is altered by inducing biological responses through electrical stimulation.
Electrical stimulation neuromodulation devices contain small electrodes that can be connected to the brain, retina, spinal cord or peripheral nerves.
Neuromodulation is used in ophthalmology to treat diseases related to photoreceptor degeneration.

A system that restores the function of the retina

How does the retina work?
The retina is a nerve tissue located in the eyeball, made up of several layers of nerve cells: photoreceptors must convert light events into electrical signals. These signals are then transmitted to the different cells that make up the retina (bipolar cells, amacrine cells, etc...), before being sent to the brain.
to the ganglion cells. These are located on the surface of the retina and their axons form the optic nerve. The signal is then sent to the visual cortex via the optic nerve.

How to act on the retina, how to stimulate the retina?

Retinal stimulation can be done in two ways:
- epi-retinal stimulation (IRIS 50 and 150) through the implantation of electrodes on the surface of the retina that stimulate ganglion cells;
- subretinal stimulation (PRIMA) which consists of placing the electrodes under the retina, in contact with the cells of the inner retina.

Implant systems

Pixium Vision's research is developing two vision restoration systems:
1) IRIS (Intelligent Retinal Implant System), the first retinal prosthesis technology platform. The device consists of three parts:
- An implant positioned on the retina. It carries electrodes that will receive visual information from a wireless transmitter and then send electrical stimulation signals to the optic nerve.
In this first generation, the implant includes 50 or 150 electrodes.
- A wireless transmitter that acts as a signal processing unit. In this device, it is a handheld computer that will process the visual data generated by the camera and transform it into an electrical signal that is transmitted to the electrodes.
- A visual interface composed of a pair of glasses equipped with a mini-camera. Here, the ATIS camera works like a human retina: it captures events in the environment and generates visual data.
IRIS50 consists of 50 electrodes and is currently in clinical trials. (CE marking is expected to be obtained in 2015).
IRIS150 has been designed and developed on the same model as IRIS 50. It includes 150 electrodes. The use of more electrodes is intended to increase the quality of vision.
In both cases, surgery is required to implant the device on the retina, usually on only one eye. The patient must then undergo a rehabilitation program to teach the brain to interpret the signals from the implant.

The current clinical trial was initiated in June 2013 in three centres in Germany, Austria and France. The study begins with an initial examination to determine whether the patient can enter the trial. After implantation, the patient participates in rehabilitation sessions with the medical team to adjust and refine the stimulation of the eye. Follow-up visits are
for a period of 18 months to monitor the condition of the eye. The safety of the procedure (the main endpoint of the study) is investigated through various ophthalmological examinations (fundus, optical coherence tomography, fluorescence angiography). Improvement of visual performance (secondary endpoint of the study) is studied.
the study) is determined by a series of tests such as light perception tests, object location and mobility tests.
The study must include between ten and twenty patients. Five patients have already been successfully implanted and the device is expected to be on the market in 2015.

2)  PRIMA, system designed to improve vision quality while simplifying the surgical procedure. He'll understand: 
- A subretinal implant composed of ultra-thin compact mosaics. As these mosaics are totally autonomous (no cable, no link), it will be possible to place several of them under the retina and thus implant up to several thousand electrodes. 
- A visual interface including the ATIS camera used for the IRIS system. A source of infrared light will simultaneously provide the mosaics with the light energy and the visual information.
- A smartphone-sized handheld computer connected to the visual interface houses the software and algorithms.

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Proof-of-concept studies were conducted in animals. A prototype of the visual interface is now available. It will allow the further development of the algorithms required for the launch of clinical trials in 2016.

The research teams

– Doctor Bernard Gilly, PhD, Chairman and CEO of Pixium Vision, founded in 2011
- Khalid Ishaque, World specialist in neuromodulation
Professor José Alain Sahel, Pierre and Marie Curie University and Vision Institute
Dr. Ryad Benosman, Pierre and Marie Curie University and Vision Institute
- Dr. Yannick Le Mer, ophthalmic surgeon, Adolphe de Rothschild Foundation
- Max Bouvy, Association of Visually Impaired Patients Valentin Hauy
- Scientific Association Ophta Biotech.



Interview with Professor José-Alain Sahel, Director of the Vision Institute at the Quinze-Vingts Hospital in Paris on the subject of his research on the treatment of serious vision disorders / September 2013.

These technological advances are shaping multiple therapeutic avenues for retinal repair, including gene therapy and stem cell transplantation, with a first clinical trial planned for 2015. It remains to be seen whether the new innovation package set up by the Ministry of Health, which aims to accelerate the availability of a therapy or technique, will support this innovation.

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