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DESCRIPTIONA retinal prosthesis is a device that replaces lost photoreceptor function by transmitting external images to an array of electrodes or via light sensors placed in the epiretinal or subretinal space. The artificial retina could potentially restore sight to patients with blindness secondary to retinal diseases, such as retinitis pigmentosa, hereditary retinal degeneration, and some forms of age-related macular degeneration.
There is ongoing research interest in developing an artificial retina that could potentially restore sight to patients with blindness secondary to retinal diseases, such as retinitis pigmentosa, hereditary retinal degeneration, and some forms of age-related macular degeneration. Two different approaches are being developed. The first is implantation of electrode arrays in the epiretinal or subretinal space to stimulate retinal ganglion cells. A second approach is the implantation in the subretinal space of light-sensitive multiphotodiode arrays which stimulate the remaining photoreceptors in the inner retina. Use of a multiphotodiode array does not require external image processing. The latter approach is being evaluated for degenerative retinal diseases such as retinitis pigmentosa, in which outer retinal cells deteriorate, but inner retinal cells remain intact for years.
Research in the United States has begun with a first generation, 16-electrode device (e.g., the Argus 16, Second Sight Medical Products, Sylmar, CA), which permitted the distinction between the presence and absence of light. The Argus II Retinal Prosthesis System (Argus II) is the second-generation device, which has 60 electrodes. The retinal prosthesis, with the electrode array, is surgically implanted in and on the eye. The system's external components consists of a small external video camera, held on eyeglass frames, that captures images that are then processed by an externally worn microcomputer. These signals are transmitted to an antenna in the prosthesis, an electronics package in the superior temporal quadrant and an electrode array implanted in the back of the eye, which in turn stimulates the optic nerve. It is hoped that future-generation devices, containing more than 1,000 electrodes, will provide more detailed vision. Three government organizations provided support for the development of the Argus II: Department of Energy, National Eye Institute at the National Institutes of Health, and National Science Foundation collaborated to provide grant funding, support for material design and other basic research for the project.
Other devices in development include the following:
The Alpha IMS was developed at the University of Tubingen, with the electronic chip design provided by the Institute for Microelectronics (IMS), Stuttgart. The second-generation Alpha IMS device has wireless power and signal transmission and is produced by Retina Implant AG (Germany). The microchip is implanted subretinally and receives input from a multiphotodiode array with 1500 elements that moves with the eye, senses incident light, and applies a constant-voltage signal at the respective 1500 electrodes. The multiphotodiode array transforms visual scenes into corresponding spatial patterns (38x40 pixels) of light intensity-dependent electric stimulation pulses with a maximum visual field of 15°.
Boston Retinal Implant Project (BRIP) uses an external camera mounted on a pair of glasses and a 100-electrode array. The image obtained by the external camera is translated into an electromagnetic signal transmitted from the external primary data coil mounted on a pair of glasses to the implanted secondary data coil attached to the cornea. Most of the volume of the implant lies outside the eye, with transscleral cables connected to a subretinal electrode array. The BRIP is a joint effort of MIT, the Massachusetts Eye and Ear Infirmary, the VA Boston Healthcare System, and the NanoScale Science & Technology Facility at Cornell University.
EPIRET3 retinal implant (Philipps-University Marburg, Marburg, Germany) is a wireless system that consists of a semiconductor camera in glasses frames and a transmitter coil outside the eye, which sends electromagnetic signals to a receiver coil in the anterior vitreous (similar to an intraocular lens), which passes them on to a receiver microchip. A stimulator chip then generates the stimulation pulses and activates a selection of 25 electrodes placed on the epiretinal surface via a connecting microcable. A second-generation wireless implant is being developed with a greater number of electrodes.
Intelligent Retinal Implant System (IRIS, Pixium Vision, Paris, France) uses an external camera that is integrated with a pair of glasses and linked by wire to a pocket computer. Receiver electronics connect via a scleral tunnel to an electrode array on the surface of the retina. Pixium Vision is also developing PRIMA, which uses a subretinal implant.
Learning Retinal Implant (Intelligent Medical Implants, Zug, Switzerland) uses an external camera on the frame of a pair of glasses and wireless data and power transfer. Receiver electronics connect via a scleral tunnel to an epiretinal implant. A retinal encoder with 100 to 1000 tunable spatiotemporal filters simulates the filtering operations performed by the ganglion cell and allows individual calibration to improve each patient’s visual perception.
Microelectrode-STS (suprachoroidal-transretinal stimulation) system (Osaka University Graduate School of Medicine, Japan) places their 9-electrode retinal prosthesis in a scleral pocket with a reference electrode in the vitreous cavity. A video camera is used to detect a visual object. Because the electrodes are at a greater distance from the retina, the resolution of the image may be lower than other devices. A proposed advantage of the STS prosthesis over epi- or subretinal prostheses is the safety of the surgical procedure, because the electrodes do not touch the retina.
The Argus II device received commercial approval in Europe in March 2011. In 2013, the U.S. Food and Drug Administration (FDA) approved a humanitarian use device exemption (HDE) for the Argus® II Retinal Prosthesis System (Second Sight Medical). HDE approval is limited to those devices that treat or diagnose fewer than 4000 people in the United States each year. The Argus® II system is intended for use in adults, age 25 years or older, with severe to profound retinitis pigmentosa who have bare light perception (can perceive light, but not the direction from which it is coming) or no light perception in both eyes, evidence of intact inner layer retina function, and a previous history of the ability to see forms. Patients must also be willing and able to receive the recommended postimplant clinical follow-up, device fitting, and visual rehabilitation.
The Alpha IMS is approved for use in Europe.
Intelligent Retinal Implant System (IRIS; Intelligent Medical Implants) is expected to receive CE approval in Europe in mid-2016.
POLICYRetinal prostheses are considered investigational.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.
Investigative is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized as a generally accepted standard of good medical practice for the treatment of the condition being treated and; therefore, is not considered medically necessary. For the definition of Investigative, “generally accepted standards of medical practice” means standards that are based on credible scientific evidence published in peer-reviewed medical literature generally recognized by the relevant medical community, and physician specialty society recommendations, and the views of medical practitioners practicing in relevant clinical areas and any other relevant factors. In order for equipment, devices, drugs or supplies [i.e, technologies], to be considered not investigative, the technology must have final approval from the appropriate governmental bodies, and scientific evidence must permit conclusions concerning the effect of the technology on health outcomes, and the technology must improve the net health outcome, and the technology must be as beneficial as any established alternative and the improvement must be attainable outside the testing/investigational setting.
POLICY HISTORY7/21/2005: Approved by Medical Policy Advisory Committee (MPAC)
8/3/2007: Policy reviewed, no changes
12/10/2009: Policy Title revised to remove Subconjunctival. Policy Description revised to add the definition of retinal prosthesis, information on the ArgusTM II, and current trial information. Policy Statement revise to remove Subconjunctival verbiage.
04/20/2011: Policy reviewed; no changes.
03/27/2012: Policy reviewed; no changes.
04/17/2013: Policy reviewed; no changes.
03/19/2014: Policy reviewed; description updated regarding FDA approval of a humanitarian use device exemption for the Argus II. Policy statement unchanged.
03/11/2015: Policy description revised to update retinal prosthesis definition and add research information and devices. Policy statement unchanged.
07/27/2015: Code Reference section updated for ICD-10.
04/22/2016: Policy description updated regarding devices. Policy statement unchanged. Investigative definition updated in policy guidelines section.
05/27/2016: Policy number A.9.03.15 added.
SOURCE(S)Blue Cross Blue Shield Association policy # 9.03.15
CODE REFERENCEThis may not be a comprehensive list of procedure codes applicable to this policy.
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