Biomedical Engineering Reference
In-Depth Information
Functional models of the Retina Implant system have now been developed and
the first tests have been performed with animals and humans. The safety of acute
electrical stimulation has been demonstrated in a preclinical study. Following
these tests, IMI performed an acute human trial involving 20 subjects suffering
from RP.
Retinal Implant Technology
Overview
The aim of the Learning Retinal Implant System is to restore vision in blind
people. This is accomplished by capturing images of the environment with a
digital camera, processing these images into electronic data signals, and then
sending them by wireless transmission to a receiver implanted in the eye. This
receiver translates these data signals into electric stimulation currents which are
applied through microelectrodes to the epiretinal side of the eye. This leads to an
activation of the underlying nerve cells that eventually elicits visual perceptions
in the brain.
The Retinal Implant device consists of three main components: the Retina
Stimulator, the Visual Interface, and the Pocket Processor. Only the Retina
Stimulator is implanted in the eye. The Visual Interface and the Pocket Processor
are external components. Additionally, a special software running on a standard
PC is provided. The software allows the user to tune certain parameters to meet
the needs of individual patients.
External Components
The Visual Interface consists of several electronic components (camera, data, and
energy transmitter) mounted in the frame of eyeglasses; it serves to record visual
information and to send data and energy to the implanted Retina Stimulator.
The Visual Interface is connected via a cable to a Pocket Processor that can be
carried on a waist belt or a strap and is responsible for image processing and
power supply.
The Visual Interface (Figure 6.1) carries the digital camera; it records images
of the environment and sends the data via cable to the Pocket Processor. The
processed data is transmitted back to the Visual Interface via the same cable.
The Visual Interface contains a wireless communication unit that transmits data
and energy to the Retina Stimulator (Figure 6.2). For this energy transmission
an electromagnetic approach is preferred. For the transmission of data an optical
channel is possible. The transmission of both energy and data has, as far as
possible, to be independent of eye movement.
The camera in the Visual Interface features a dynamic range which allows for
vision both indoor and outdoor without additional light sources.
The Pocket Processor contains proprietary software that processes the camera
images and translates this information into data signals for the Retina Stimulator.
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