Patent Publication Number: US-2017368351-A1

Title: Retinal prosthesis

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to implantable medical devices, and specifically to a retinal prosthesis. 
     BACKGROUND 
     Retinal malfunction, due to degenerative retinal diseases, is a leading cause of blindness and visual impairment. Implantation of a retinal prosthesis is a technology for restoring some useful vision in individuals suffering from retina-related blindness. 
     The retina is a multi-layered light-sensitive structure that lines the posterior, inner part of the eye. The retina contains photoreceptor cells, rods and cones, which capture light and convert light signals into neural signals transmitted through the optic nerve to the brain. 
     SUMMARY OF THE INVENTION 
     In accordance with some applications of the present invention, intraocular apparatus is provided for implantation entirely in a subject&#39;s eye. The intraocular apparatus is typically implanted for stimulation of the retina of the subject suffering from a retinal disease, in order to restore at least partial vision in the subject. The intraocular apparatus typically comprises a photosensor array comprising a plurality of photosensors configured to receive an ambient image, a power source configured to power the apparatus, and a flexible 0.4-3 mm electrical connector, connecting the photosensor array to the power source. 
     Typically, the apparatus further comprises an electrode array comprising electrodes, and driving circuitry coupled to the power source and to the photosensor array, and configured to receive power from the power source to drive the electrodes to apply current pulses to the retina in response to signals from the photosensor array, in order to stimulate the retina. 
     In accordance with some applications of the present invention, the power source comprises at least one energy receiver configured to receive non-visible light, typically infra-red light, through the lens of the eye and to extract power from the non-visible light. Typically, the at least one energy receiver comprises at least first and second energy receivers, positioned on either side of the photosensor array, and the flexible electrical connector is a first flexible electrical connector and connects the first energy receiver to the photosensor array, and the intraocular apparatus further comprises a second flexible electrical connector, which connects the second energy receiver to the photosensor array. 
     Additionally or alternatively, the power source comprises at least one power storage element, for example, a rechargeable battery configured to power the intraocular apparatus when the intraocular apparatus is not receiving energy from outside of the eye. For some applications, the power storage element stores sufficient charge for operation of the intraocular apparatus for 1-10 hours. 
     Typically, the at least one power storage element comprises first and second power storage elements, positioned on either side of the photosensor array, and the flexible electrical connector is a first flexible electrical connector and connects the first power storage element to the photosensor array and the intraocular apparatus further comprises a second flexible electrical connector, which connects the second power storage to the photosensor array. 
     There is therefore provided in accordance with some applications of the present invention, intraocular apparatus configured to be implanted entirely in a subject&#39;s eye, the intraocular apparatus including: 
     a photosensor array including a plurality of photosensors configured to receive an ambient image; 
     a power source, configured to power the intraocular apparatus; and 
     a flexible 0.4-3 mm electrical connector, connecting the photosensor array to the power source. 
     For some applications, the flexible connector includes thinned silicon. 
     For some applications, the photosensor array, the power source and the flexible electrical connector are formed along a single piece of thinned silicon. 
     For some applications, the power source includes at least one power storage element, configured to power the intraocular apparatus when the intraocular apparatus is not receiving energy from outside of the eye. 
     For some applications, the at least one power storage element includes a rechargeable battery configured to store sufficient charge for operation of the intraocular apparatus for 1-10 hours. 
     For some applications, the rechargeable battery has a total charge of 0.1-10 mAh. 
     For some applications, the at least one power storage element includes a plurality of stacked dies, each die including a plurality of miniature batteries integrated into the die. 
     For some applications, the at least one power storage element includes first and second power storage elements, positioned on either side of the photosensor array, 
     the flexible electrical connector is a first flexible electrical connector and connects the first power storage element to the photosensor array, and 
     the intraocular apparatus further includes a second flexible electrical connector, which connects the second power storage element to the photosensor array. 
     For some applications, the power source includes at least one energy receiver configured to receive non-visible light through the lens of the eye and to extract power from the non-visible light. 
     For some applications, the at least one energy receiver is configured to receive light with wavelength that is outside of 390-700 nm. 
     For some applications, the at least one energy receiver includes first and second energy receivers, positioned on either side of the photosensor array, 
     the flexible electrical connector is a first flexible electrical connector and connects the first energy receiver to the photosensor array, and 
     the intraocular apparatus further includes a second flexible electrical connector, which connects the second energy receiver to the photosensor array. 
     For some applications, the power source further includes at least one power storage element, configured to power the intraocular apparatus when the intraocular apparatus is not receiving energy from outside of the eye. 
     For some applications, the apparatus further includes an extraocular device including a light source configured to emit the non-visible light toward the eye, wherein the at least one power storage element is configured to store power extracted from the non-visible light for at least one hour, and wherein the intraocular apparatus is configured to use the stored power to power the intraocular apparatus. 
     For some applications, the light source includes a laser. 
     For some applications, the at least one power storage element includes a rechargeable battery configured to receive the power extracted by the energy receiver. 
     For some applications, the intraocular apparatus further includes (i) an electrode array including electrodes, and (ii) driving circuitry coupled to the power source and to the photosensor array, and configured to receive power from the power source to drive the electrodes to apply currents to the retina in response to signals from the plurality of photosensors in the photosensor array. 
     There is further provided in accordance with some applications of the present invention, intraocular apparatus configured to be implanted entirely in a subject&#39;s eye, the intraocular apparatus including: 
     a photosensor array including a plurality of photosensors configured to receive an ambient image; 
     a power source, configured to power the intraocular apparatus; and 
     a flexible electrical connector, connecting the photosensor array to the power source, 
     the photosensor array, the power source and the flexible electrical connector being formed along a single piece of thinned silicon. 
     There is further provided in accordance with some applications of the present invention, intraocular apparatus configured to be implanted entirely in a subject&#39;s eye, the intraocular apparatus including: 
     a photosensor array including a plurality of photosensors, configured to receive an ambient image; and 
     a flexible power source including thinned silicon and coupled to the plurality of photosensors, configured to power the intraocular apparatus and including a photovoltaic energy receiver configured to receive non-visible light and to extract power from the non-visible light, 
     a photovoltaically-active region of the flexible power source having an area of 5-50 mm 2 , and 
     at least one photovoltaically-active site in the photovoltaically-active region of the flexible power source being disposed 0.4-3 mm from a nearest one of the plurality of photosensors to the site. 
     There is further provided in accordance with some applications of the present invention, intraocular apparatus configured to be implanted entirely in a subject&#39;s eye, the intraocular apparatus including:
         a power source, configured to power the intraocular apparatus, the power source including:
           (i) at least one energy receiver configured to receive non-visible light through the lens of the eye and to extract power from the non-visible light; and   (ii) at least one power storage element, configured to power the intraocular apparatus when the intraocular apparatus is not receiving energy from outside of the eye;   
           a plurality of stimulating electrodes;   a photosensor array including a plurality of photosensors, each photosensor configured to detect photons and to generate a signal in response thereto; and   driving circuitry, coupled to the power source and to the photosensors, and configured to receive the signals from the photosensors and to utilize the voltage drop to drive the electrodes to apply currents to a retina of the eye in response to the signals from the photosensors.       

     The present invention will be more fully understood from the following detailed description of applications thereof, taken together with the drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of intraocular apparatus implanted in an eye of a subject, in accordance with some applications of the present invention; 
         FIGS. 2A and 2B  are schematic illustrations of top and side views respectively of intraocular apparatus for implantation in an eye of a subject, in accordance with some applications of the present invention; 
         FIG. 3  is a schematic illustration of intraocular apparatus implanted in an eye of a subject, in accordance with some applications of the present invention; 
         FIG. 4  is a schematic illustration of an additional configuration of intraocular apparatus implanted in an eye of a subject, in accordance with some applications of the present invention; 
         FIG. 5  is a schematic illustration of intraocular apparatus implanted in an eye of a subject, in accordance with some applications of the present invention; and 
         FIG. 6  is a schematic illustration of an example of a power source of the intraocular apparatus, in accordance with some applications of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Reference is first made to  FIG. 1 , which is a schematic illustration of intraocular apparatus  20  implanted in an eye  10  of a subject, in accordance with some applications of the present invention. As shown, apparatus  20  is separated into a plurality of modules which are electrically and mechanically coupled and which are implanted as a single unit onto retina  60  to together form intraocular apparatus  20 . Typically, apparatus  20  comprises a retinal prosthesis module  28  comprising a photosensor array  24  which comprises a plurality of photosensors and which receives an ambient image through lens  40  of eye  10 . Typically, lens  40  is a native or a prosthetic lens. Apparatus  20  further comprises a power source module  30  configured to power apparatus  20 , and a flexible electrical connector  50  mechanically and electrically connecting photosensor array  24  to power source  30 . Typically, flexible electrical connector  50  has a length of at least 0.4 mm and/or less than 3 mm, and typically comprises thinned silicon. As shown in  FIG. 1 , for some applications, apparatus  20  comprises more than one, e.g., first and second, power sources modules  30 , positioned on either side of retinal prosthesis module  28 . In such cases, flexible electrical connector  50  comprises first and second flexible electrical connectors  50  connecting both power sources modules  30  to retinal prosthesis module  28 . Typically, retinal prosthesis module  28 , power source module  30  and flexible electrical connector  50  are formed along a single piece of thinned silicon. 
     Typically, retinal prosthesis module  28  further comprises an electrode array  22  comprising stimulating micro-electrodes  23 . Retinal prosthesis module  28  additionally comprises driving circuitry  26  (typically including image processing electronics) which is coupled to power source module  30  and to photosensor array  24 . Driving circuitry  26  receives power from power source  30  to drive electrodes  23  to apply currents to retina  60  in response to signals from photosensor array  24  in retinal prosthesis module  28 , in order to stimulate retina  60 . 
     Typically, implanting intraocular apparatus  20  as a plurality of electrically and mechanically connected modules as shown in  FIG. 1 , reduces mechanical stress on retina  60  during motion of eye  10 . This is in contrast to implanting onto the retina a single, high-volume unit which may apply mechanical stress to the retina leading to retinal detachment or separation of the retinal implant from the retina. Additionally, the natural curvature of retina  60  may make it difficult to implant a single, large-area unit onto the retina. Apparatus  20 , being divided into separate modules which are electrically and mechanically connected by flexible connectors  50 , is typically flexible and can bend in order to conform to the natural curvature of retina  60 , facilitating proper implantation and attachment of apparatus  20 . 
     Reference is now made to  FIGS. 2A and 2B , which are schematic illustrations of top ( FIG. 2A ) and side ( FIG. 2B ) views of apparatus  20 , in accordance with some applications of the present invention.  FIGS. 2A and 2B  show apparatus  20  prior to implantation in eye  10  and prior to bending of flexible connectors  50  for facilitating implantation and conforming to the natural curvature of the eye. As shown in  FIGS. 2A-B , power source modules  30  are positioned on either side of retinal prosthesis module  28  and are mechanically and electrically connected to retinal prosthesis module  28  by flexible connectors  50 . Typically, flexible connector  50  comprises thinned silicon, and retinal prosthesis module  28 , power source module  30  and flexible electrical connector  50  are formed along a single piece of thinned silicon. The thinned silicon is typically durable and bio-compatible. Additionally, the thinned silicon functions as an electrical conducting material typically without additional use of a conductive metallic layer, thus enhancing the bio-compatibly of connector  50 . Flexible connector  50  is typically fabricated to an ultra-thin conductive silicon strip (e.g., 20-50 microns thick) by conventional fabrication processes known in the art. For some applications, techniques described in U.S. Pat. No. 7,560,802, which is incorporated herein by reference are practiced in combination with techniques and apparatus described herein, with regard to thinned silicon and implementation of a conducting silicon strip. 
     Reference is again made to  FIG. 1  and  FIGS. 2A-B . Typically, apparatus  20  is implanted onto retina  60  and anchored to a sclera  80  of eye  10  using one or more anchoring elements  42 , e.g., anchoring tacks. As shown in  FIG. 2A  flexible connector  50  is shaped to define at least one, e.g., two, holes  43  shaped and sized to receive anchoring elements  42  therethrough. When apparatus  20  is implanted onto retina  60 , anchoring elements  42  are positioned in holes  43  and penetrate sclera  80  to secure apparatus  20  to eye  10 . Positioning anchoring elements  42  in holes  43  between generally rigid power sources  30 , and pressing flexible connector  50  to retina  60 , typically causes the bending of apparatus  20  and conforming of apparatus  20  to the natural curvature of retina  60 . It is noted that apparatus  20  may be secured to eye  10  by using other anchoring mechanisms. 
     Reference is now made to  FIG. 3 , which is a schematic illustration of intraocular apparatus  20  implanted in eye  10  of the subject, in accordance with some applications of the present invention. As provided by some applications, power source module  30  comprises energy receiver  32 . For some applications, energy receiver  32  comprises photovoltaic cells configured to receive light and convert the optical energy from the light into electrical energy for powering apparatus  20 . Energy receiver  32  receives non-visible light, e.g., light outside of 390-700 nm, typically infrared light, through lens  40  of eye  10  and extracts power from the non-visible light to power apparatus  20 . For some applications, energy receiver  32  receives non-visible light from an extraocular device (not shown) comprising a light source, e.g., a laser or an LED, which emits the non-visible light, e.g., infrared light, toward eye  10 . For some applications, techniques described in U.S. Pat. No. 8,150,526, which is incorporated herein by reference, are practiced in combination with techniques and apparatus described herein, with regard to an extraocular device comprising a light source. Additionally or alternatively, energy receiver  32  is configured to extract power from ambient visible and/or non-visible light in a highly lit environment, and does not rely on light from an extraocular laser or other dedicated component of apparatus provided to power intraocular apparatus  20 . As shown, energy receivers  32  are positioned on retina  60  facing the iris of eye  10 , for absorbing the light. 
     As shown in  FIG. 3 , apparatus  20  comprises two energy receivers  32  positioned on either side of retinal prosthesis module  28 , each energy receiver  32  being connected electrically and mechanically to module  28  by flexible connector  50 . Typically, power from energy receivers  32  is conducted through flexible connector  50  to retinal prosthesis module  28  to drive driving circuitry  26  to drive electrodes  23  to apply currents to retina  60  in response to signals from photosensor array  24  of retinal prosthesis module  28 , in order to stimulate retina  60 . 
     Typically, by partitioning apparatus  20  into several relatively small connected units and having two energy receivers  32 , rather than one larger energy receiver, the light absorbing area of apparatus  20  is increased without unduly increasing the size of retinal prosthesis module  28 , thereby enhancing light reception by apparatus  20  and also facilitating widening the scanning angle with respect to the center of the iris. 
     Reference is now made to  FIG. 4 , which is a schematic illustration of an additional configuration of intraocular apparatus  20  implanted in eye  10  of the subject, in accordance with some applications of the present invention. For some applications, power source  30  comprises flexible power source  36  comprising thinned silicon (similar to flexible connector  50 ) and coupled to retinal prosthesis module  28  and configured to power apparatus  20 . Flexible power source  36  typically comprises a photovoltaic energy receiver (the thinned silicon has PN junctions on an upper surface thereof which act as photovoltaic cells) configured to receive non-visible light and to extract power from the non-visible light, similar to energy receiver  32  described hereinabove with reference to  FIG. 3 . Typically, flexible power source  36  has a photovoltaically-active region having an area A of 5-50 mm 2 . Additionally, at least one photovoltaically-active site in the photovoltaically-active region of flexible power source  36  is disposed at a distance D 1  which is at least 0.4 mm and/or less than 3 mm from a nearest one of the plurality of photosensors in photosensor array  24  to the site. Typically, flexibility of power source  36  enables spreading power source  36  over a relatively large area of retina  60 , enabling the capturing of a relatively large amount of light and converting it to electrical power for powering apparatus  20 . It is noted that although flexible power source  36  is shown in  FIG. 4  as being on both sides of retinal prosthesis module  28 , the scope of the present invention includes having flexible power source  36  on only one side of retinal prosthesis module  28 . 
     Reference is now made to  FIG. 5 , which is a schematic illustration of intraocular apparatus  20  implanted in eye  10  of the subject, in accordance with some applications of the present invention. For some applications, power source module  30  comprises at least one power storage element  34 . Power storage element  34  typically stores power to provide power to apparatus  20  when apparatus  20  is not receiving energy from outside of the eye. Typically, power storage element  34  comprises a battery, and/or a high value capacitor, and/or a supercapacitor. 
     As noted hereinabove, for some applications, power storage element  34  comprises a rechargeable battery configured to store sufficient charge for operation of apparatus  20  for 1-10 hours, e.g., 1-4 hours. Typically the rechargeable battery has a total charge of greater than 0.1 mAh and/or less than 10 mAh, e.g. in the range of 0.1 mAh-10 mAh. 
     For some applications, power storage element  34  comprises a plurality of miniature batteries, e.g., solid state batteries. Typically, power storage element  34  comprises a plurality of stacked dies, each die comprising a plurality of miniature batteries integrated into the die for gaining larger charge capacity for generally the same area. 
     Typically, power storage element  34  is charged by energy-receiving photovoltaic cells in energy receiver  32 . For such applications, the photovoltaic cells are placed inside power storage element  34 , typically on a surface of power storage element  34  facing the iris of eye  10 . When eye  10  is illuminated, the light is received by the photovoltaic cells, and power is extracted from the light and conducted to power storage element  34  where the power is stored. For some applications, a diode, e.g., a Schottky diode, is used to ensure that the photovoltaic cells only drive current into power storage element  34 , but do not consume current from power storage element  34 . Alternatively, a rectification circuit, e.g., implemented in a CMOS ASIC, is used to inhibit the photovoltaic cells from applying a load to the retinal prosthesis module  28 . 
     As shown in  FIG. 5 , apparatus  20  comprises two power storage elements  34 , positioned on either side of retinal prosthesis module  28 , each power storage element  34  being connected electrically and mechanically to module  28  by flexible connector  50 . Typically, power from power storage element  34  is conducted through flexible connector  50  to retinal prosthesis module  28  to drive driving circuitry  26  to drive electrodes  23  to apply current pulses to retina  60  in response to signals from photosensor array  24  of retinal prosthesis module  28 , in order to stimulate retina  60 . 
     Typically, when power is stored in power storage element  34 , apparatus  20  can be powered also when apparatus  20  is not receiving light from outside of the eye. Therefore, it is not necessary to continuously illuminate apparatus  20 . Typically, in cases in which apparatus  20  does not comprise a power storage element  34 , in order to provide continuous power to apparatus  20 , an extraocular light source, e.g., an infra-red laser is provided. Typically the laser is mounted on a pair of eyeglasses worn by the subject and is positioned such that light emitted by the laser is received by apparatus  20 . Use of power storage element  34  may allow the subject to illuminate the eye only when charge in power storage element  34  is low, without the need for continuous wearing of glasses and for continuous illumination of the eye by an extraocular light source. Thus, apparatus  20  is not continuously dependent on an extraocular light source for providing power. In other words, when sufficient energy is stored inside apparatus  20  (e.g., inside storage element  34 ), there is generally no need for illumination of the eye by a dedicated extraocular light source mounted on glasses. Instead, the eye is illuminated by a charging light source that is held in front of the eye for a typically short amount of time which is sufficient to charge storage element  34 . Thereby, the subject is offered the option of not wearing special-purpose glasses (for example, the subject may wear any type of glasses for esthetic or corrective reasons). 
     Additionally or alternatively, a scanning angle of eye  10  is not limited by the size of the light beam from the extraocular light source. That is, when the subject gazes to the right or left and an extraocular power source is therefore not illuminating energy receiver sufficient power remains in power storage element  34  for intraocular apparatus  20  to continue to operate. 
     Additionally or alternatively, due to use of power storage element  34 , implantation of some or all components of apparatus  20  (e.g., power storage element  34  in particular), is not limited to a particular area of the retina, e.g., the fovea. Thus, for some applications, the scope of the present invention includes implanting more than one apparatus  20  in a single procedure in a single eye, or subsequently implanting a second apparatus  20 , e.g., when a first, previously-implanted, apparatus  20  has ended its lifetime or is superseded by a newer version of apparatus  20 . 
     Reference is now made to  FIG. 6 , which is a schematic illustration of power source  30  of intraocular apparatus  20 , in accordance with some applications of the present invention. As shown in  FIG. 6 , power source  30  comprises power storage element  34  comprising a plurality of stacked dies each die comprising miniature batteries, e.g., solid state batteries (SSB), integrated into the die. Power source  30  additionally comprises energy receiver  32  comprising a plurality of photovoltaic cells placed on an interposer that connects the photovoltaic cells. As shown, photovoltaic cells are placed on a top side of the power storage element. A transparent cap  100  allows passage of light therethrough toward the photovoltaic cells of power receiver  32 . Typically, a diode  120 , e.g., a Schottky diode, is used to ensure that the photovoltaic cells only drive current into power storage element  34 , but do not consume current from power storage element  34 . 
     It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof that are not in the prior art, which would occur to persons skilled in the art upon reading the foregoing description.