June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
An Optimal Power Coil Configuration to Minimize Surgical Cut for Intraocular Retinal Prostheses
Author Affiliations & Notes
  • Yu Zhao
    Electrical Engineering, California Institute of Technology, Pasadena, CA
  • Charles DeBoer
    Electrical Engineering, California Institute of Technology, Pasadena, CA
  • Mandheerej Nandra
    Electrical Engineering, California Institute of Technology, Pasadena, CA
  • James Weiland
    Doheny Eye Institute, Los Angeles, CA
  • Mark Humayun
    Doheny Eye Institute, Los Angeles, CA
  • Yu-Chong Tai
    Electrical Engineering, California Institute of Technology, Pasadena, CA
  • Footnotes
    Commercial Relationships Yu Zhao, None; Charles DeBoer, None; Mandheerej Nandra, None; James Weiland, Second Sight Medical Products, Inc. (F); Mark Humayun, Bausch & Lomb (F), Bausch & Lomb (C), Bausch & Lomb (P), Bausch & Lomb (R), Bausch & Lomb (S), Alcon (C), Alcon (R), Iridex (P), Iridex (R), Replenish (I), Replenish (C), Replenish (R), Replenish (S), Second Sight (F), Second Sight (I), Second Sight (C), Second Sight (P), Second Sight (R), Second Sight (S), Regenerative Patch Technologies (I), Regenerative Patch Technologies (C); Yu-Chong Tai, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 1056. doi:
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    • Get Citation

      Yu Zhao, Charles DeBoer, Mandheerej Nandra, James Weiland, Mark Humayun, Yu-Chong Tai; An Optimal Power Coil Configuration to Minimize Surgical Cut for Intraocular Retinal Prostheses. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1056.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

Power coils used in current telemetries powering the epiretinal, subretinal and suprachoroidal prosthetic devices, such as microfabricated planar coil with metal electroplating and wire-wound coil, are not suitable/ideal for intraocular implantation as they are usually thick, rigid and large. For intraocular implantation, we propose a foil coil as an optimized configuration. It demonstrates not only better electrical performance, but also superior mechanical flexibility and bendability allowing the surgeon to implant through a minimal incision.

 
Methods
 

The lens capsule is a possible intraocular implantation site for the telemetry coils, which also sets the size and mass constraints. This implantation is similar to the common intraocular lens implantation. While making the best use of the coil winding window, it is still necessary to make the coil flexible for minimally invasive surgical implantation. Flexural stiffness, i.e., resistance to bending, equals to the product of the Young’s modulus E and second moment of area I reflecting the material stiffness and its geometrical cross section, respectively. Given same constructing metal, second moment of area varies with cross-sectional size and geometry (Fig. 1). The long-span high-aspect ratio foil strip can achieve smallest I and therefore the most flexibility. The strip was fabricated using a parylene-metal-parylene sandwich structure. The thermally deposited metal is thin (0.25 μ m) and patterned to form a 1-mm-wide stripe to fit into lens capsule. After the foil was dry-peeled off from the silicon substrate and manually wound into a circular coil, the original width of the encapsulated metal foil becomes the equivalent thickness of the coil.

 
Results
 

To demonstrate the surgical feasibility, the coil was implanted into the lens capsule of a porcine eye (Fig. 2). The coil was compressed and inserted into a porcine lens capsule through a capsulorhexis. After implantation the forceps were withdrawn and the coil regained its circular shape (dotted circle in the middle panel). By observing the implanted coil after removal of the iris, the full recovery of the coil shape was achieved in vitro.

 
Conclusions
 

Foil coil configuration has been theoretically proven and experimentally demonstrated to be more bendable, thus less invasive during implantation. The resulting smaller surgical incision has the potential to reduce post operative recovery time.

     
Keywords: 688 retina • 412 age-related macular degeneration • 701 retinal pigment epithelium  
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