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    Retinal prosthesis offers hope to blind patients

    Argus II provides more function to patients while wearing the device

    An artificial retinal prosthesis allows patient with retinitis pigmentosa (RP) to locate objects, detect movement, and improve orientation and mobility skills.

    The Argus II Retinal Prosthesis System (Second Sight Medical Products), which was approved by the U.S. Food and Drug Administration in 2013, is limited to RP patients who are currently no light perception (NLP) or bare LP.

    How the device works

    The device consists of:

    • A 60-electrode array surgically implanted over the macula (Figure 1) driven by a neurostimulator attached to the outside of the sclera

    • An inductive coil link used to transmit power and video data to the implant

    • An external belt-worn video processing unit (VPU)

    • A miniature video camera mounted on a pair of glasses

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    The video camera captures visual information and relays it to the VPU. The VPU in turn digitizes the signal in real time and creates a series of stimulus pulses. These pulses are then transmitted to the microelectrode array on the retina where they stimulate the remaining cells in the retina. The nerve cells in the retina transmit the visual information along the optic nerve to the brain, creating the perception of patterns of light. The patient then must learn to interpret these visual patterns, regaining some functional vision.

    The prosthesis itself is implanted surgically, typically by an experienced vitreoretinal surgeon, using existing surgical techniques. Median surgery time is approximately three hours. After the implantation, most patient need to work with occupational or low-vision rehabilitation specialists for up to three months to understand the device and how to use it to achieve their goals.

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    Steven Ferrucci, OD, FAAO
    Dr. Ferrucci is Chief of optometry at the Sepulveda VA, as well as a professor at the Southern California College of Optometry. He ...

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    Optometry Times A/V