High-tech In Low Vision

Multiple approaches to artificial vision are available or in development.

By Aaron Tarbett, OD, FAAO

New technology in eye care is constantly pushing the limits of what was thought to be impossible less than a decade ago. Keeping pace with these new devices and engineering marvels is virtually impossible for the hard-charging eye care clinician. We developed this new column, "Artificial EYE-Telligence,” to share the latest and greatest information, highlighting articles by experts in the field of emerging and future technologies. Beware! The information in this column is sure to change our profession forever!

—Section Editor Andrew S. Morgenstern, OD, FAAO
(chairman of the American Optometric Association, New Technology Committee)

We are here, finally. We can now say we have the technical ability to make the blind see. Not just for the selected experimental few, but for the masses. Although the level of artificial sight that devices can provide is still rudimentary, giving sight to the blind and visually impaired is no longer science fiction. A significant number of technologies developed all around the globe are coming into their own, enabling the blind and visually impaired to perceive their surroundings in a variety of ways.

Because the eye-brain extension is a complex amalgamation of many systems to produce vision, a failure in any individual system may require a uniquely technical fix. For this reason, each type of visual impairment may require a different type of device to restore vision. We are lucky, then, that multiple approaches are being used by developers of systems for artificial vision. Several of these technologies, at various stages of development from prototype to commercially available, are outlined in this article.

Argus II Retinal Prosthesis System

The Argus II Retina Prosthesis System (Second Sight Medical Products Inc.) is the only retinal prosthetic device that has received clearance from the US Food and Drug Administration (FDA) and that is reimbursed by the Centers for Medicare and Medicaid Services. At a cost of approximately $115,000.00, it is labeled to treat vision loss due to advanced retinitis pigmentosa. Trials are underway in Europe investigating the use of the Argus II in other ocular conditions such as macular degeneration.

Figure 1. The ocular implant of the Argus II consists of an antenna and a case, housing the inductive coil link used to transmit data to the 60-channel microelectrode array.

Figure 2. Each of 1,500 individual pixel cells in the Alpha IMS Retinal Implant contains a light-sensitive photodiode, a logarithmic differential amplifier, and a 50- × 50-μm iridium electrode into which electrical stimuli to the retina are guided.

The Argus II consists of three parts: a miniature video camera located in the bridge of a pair of glasses, a video processing unit (VPU), and a retinal implant. The video camera transmits captured images to the VPU through a cable.1 The VPU processes the image, down-sampling it to a 6 × 10 pixelated grid and sending it back to the glasses. It is then transmitted via radio frequency to the retinal implant, triggering small electrical impulses that bypass damaged photoreceptors to stimulate anterior retinal layers. With time and experience, patients learn to interpret recognizable patterns of light generated by the implant.

The ocular implant consists of an antenna and a case housing an inductive coil link used to transmit data to the 60-channel microelectrode array (Figure 1). The antenna and housing are harnessed to the eye with polymer straps. The microelectrode array is inserted into the vitreous cavity and physically tacked to the anterior surface of the retina during a 4-hour surgery that includes concurrent phacoemulsification and vitrectomy. Due to the invasive nature of the procedure, a 1-night inpatient stay may be required.

Although the vision provided is rudimentary, with an appearance similar to an old high school scoreboard, the Argus II does provide significant improvement in vision and spatial motor tasks. Typically, patients receiving the implant showed improvement from light perception (and visual acuity below 2.9 logMAR or 20/15,887 Snellen) to hand motion and counting fingers. One recipient achieved visual acuity of 20/1260. Minimal side effects have been reported, the most common being conjunctival erosion or dehiscence over the extraocular implant (antennae and housing). These were successfully treated in all but one patient who had to have the device removed.2,3

The Argus II is available commercially for patients who qualify. Criteria for device implantation include age of 25 years or greater, severe to profound outer retinal degeneration, some residual light perception or ability to respond to electrical stimulation, and history of previously functional vision.1 More than 100 devices have been implanted to date. The device is available in multiple cities across the United States and Canada.

Alpha IMS Retinal Implant

The Alpha IMS Retinal Implant (Retinal Implant AG), although not cleared by the FDA, has received the CE Mark in Europe and is available commercially overseas. This subretinal implant is placed between the retinal pigment epithelium and the neurosensory retina. The implant consists of a silicon chip about 3 x 3 mm in size and 70 μm thick. Each of the 1,500 individual pixel cells contains a light-sensitive photodiode, a logarithmic differential amplifier, and a 50- x 50-μm iridium electrode into which electrical stimuli to the retina are guided (Figure 2).

Subretinal implants require more difficult implantation methods and power sourcing, making the results more ambiguous with regard to efficacy in vision restoration.4 It is unknown when, or whether, this device will become available in the United States.

Bio-Retina

Clinical trials of the battery- and antenna-free Bio-Retina (Nano Retina.; Figure 3) retinal implant are planned, according to the company. This 3- × 4-mm microchip has a 24 × 24 pixel grid (576 photodetectors) and a second-generation version is projected to have a 72- × 72-pixel grid (5,184 photodetectors). A Nano Retina official has been quoted saying that the implant will provide visual acuity of 20/300 or better after a minimally invasive 30-minute procedure in which the implant is glued to the surface of the retina.5 According to a description in the consumer press, 600 needle-like electrodes that extend from the Bio-Retina implant into the retina stimulate healthy retinal cells to create an image. The implant is innovatively powered by a pair of spectacles that projects a near-infrared laser onto the implant to charge a photovoltaic cell.6 This device has not entered clinical trials. It is not cleared by the FDA or available commercially in the United States.

Figure 3. Needle-like electrodes extend from the Bio-Retina implant into the retina, stimulating healthy retinal cells to create an image.

BrainPort V100

The BrainPort V100 (Wicab) is a novel nonsurgical device for “visual” restoration. It uses an electrode array placed onto the surface of the tongue rather than inside the eye. The innovative technology is based on the principle of sensory substitution. As succinctly put by a pioneer in the field of neuroplasticity, Paul Bach-y-Rita, MD, PhD, “We see with our brains, not with our eyes.”

The device makes use of the highly innervated and moist surface of the tongue to efficiently transfer electrically simulated images captured by a wearable camera. The camera, with a 90° field of view, is housed in a pair of sunglasses that connects to a smartphone-sized controller or base unit. The base unit translates the captured image into an electrotactile pattern that is displayed on the tongue via a thin, postage stamp-sized resin pad containing 400 electrodes.7 The device has been nicknamed “the lollipop” because of its appearance in use.

The electrotactile stimulation of the tongue is said to feel similar to the sensation that champagne bubbles create. The intensity of the stimulation varies with color to create a depiction of the image; white has the strongest stimulation, and black has no stimulation.7 The brain then uses the information from the tongue as though it were coming from the eyes, and patients can “see” their environment. With proper training, patients can perceive size, shape, location, and motion of objects in their environment.8 A minimum training period of 10 hours is required before the device is dispensed for use.

The BrainPort V100 is intended for patients with near total or total blindness and is meant to complement rather than replace other assistive aids such as a red-tipped cane or service dog. It is an investigational device currently in FDA clinical trials at seven sites in the United States; it is not FDA approved and is not available commercially.

OrCam

The OrCam (Orcam Technologies) assistive technology device translates visual information into auditory information. It is a form of optical character recognition (OCR) technology, similar to the type used with some video magnifier closed circuit televisions. However, the OrCam allows OCR to take place in everyday environments, or what its developers have termed “text in the wild.”9

The OrCam consists of two parts, a head unit and base unit. The head unit is a miniature camera combined with a bone-conducting earpiece mounted to the right side of the patient’s spectacles. The camera is connected to the base unit by a cable and mounted on the user’s belt. It contains the hardware and software to translate text or objects into speech.10

Users point with the index finger at something they want to read or see, whether a street sign, a newspaper article, or a friend’s face that the device has been taught to recognize. The unit converts that visual information to speech that is relayed by the earpiece. The device is portable and removable; the mount is permanent, but the device can be shifted to different pairs of spectacles as long as they have a mount. Because the device is mounted on the temple of a pair of glasses, it can easily be removed and remounted if the individual changes glasses.

Use of the device is not limited to a specific type of visual impairment, but individuals who are blind—or who have vision so impaired that they cannot find written text to aim at—will likely not benefit from it. Similarly, individuals with severe hearing impairment may not benefit.

Research on the OrCam is ongoing, and it is currently not available commercially. Although a limited number of devices were released in 2013, the company says the product is still in development and is hoped to be available soon. The projected cost is $3,500, and a waiting list is available on the company’s website.

FingerReader

Another unique device that utilizes OCR technology is the FingerReader (Fluid Interfaces Group; Massachusettes Institutue of Technology Media Lab ). This is a finger-worn OCR system that transforms written text to speech. The Fluid Interfaces Group conducted focus group sessions with blind users and found a strong desire to have a small, portable device that supports free movement, requires minimal setup, and works quickly to convey written print such as a restaurant menu.

The device is worn like a ring on the index finger and holds a high-resolution miniature video camera at a fixed distance. The finger acts as a cursor, and the wearer uses his or her sense of touch to scan the surface of a printed page. The FingerReader hardware provides tactile feedback on direction and orientation via vibration motors in the ring. The device has a simple interface that allows easy and efficient setup.11

The FingerReader is still only a prototype and not commercially available, but in the future, it may prove to be a useful assistive aid. n

1. Second Sight. www.2-sight.eu/images/stories/2-sight/pdf/product-info-brochure-ee.pdf. Accessed May 7, 2015.

2. Humayun MS, Dorn JD, da Cruz L, et al. Interim results from the international trial of Second Sight’s visual prosthesis. Ophthalmology. 2012;119(4):779-788.

3. Ahuja AK, Dorn JD, Caspi A, et al; Argus II Study Group. Blind subjects implanted with the Argus II retinal prosthesis are able to improve performance in a spatial-motor task. Br J Ophthalmol. 2011;95:539-543.

4. Stingl K, Bartz-Schmidt KU, Besch D, et al. Artificial vision with wirelessly powered subretinal electronic implant alpha-IMS. Proc Biol Sci. 2013;280(1757):20130077. doi: 10.1098/rspb.2013.0077.

5. Retinal Implant. WebRN-Macular Degeneration.com website. http://www.webrn-maculardegeneration.com/retinal-implant.html. Accessed April 21, 2015.

6. Cooper A. Bio-Retina implant could give laser-powered sight to the blind. Popular Science. July 16, 2012. http://www.popsci.com/technology/article/2012-06/bio-retina-implant-could-give-sight-blind-laser-power. Accessed April 21, 2015.

7. Arnoldussen A, Fletcher DC. Visual perception for the blind: The BrainPort Vision Device. Retinal Physician. January 1, 2012:32-34.

8. Arnoldussen A, Nemke C, Hogle R, Skinner K. BrainPort plasticity: balance and vision applications. Proceedings of the 9th International Conference on Low Vision; July 7-17, 2008; Montreal.

9. Markoff J. Device from Israeli start-up gives the visually impaired a way to read. New York Times. June 3, 2013. http://www.nytimes.com/2013/06/04/science/israeli-start-up-gives-visually-impaired-a-way-to-read.html. Accessed April 21, 2015.

10. OrCam User Guide Version 3.0. OrCam Technologies Ltd. 2014. http://www.orcam.com/wp-content/uploads/2014/02/OrCam-User-Manual-3-Early-Release-Feb4.pdf. Accessed April 21, 2015.

11. Shilkrot R, Huber J, Wong ME, et al. FingerReader: a wearable device to explore text on the go. Paper presented at: CHI 2015; April 18-23, 2015; Seoul, South Korea.

Section Editor: Andrew S. Morgenstern, OD, FAAO
• Optometric subject matter expert, Booz Allen Hamilton
• Contract support, Vision Center of Excellence, Walter Reed National Military Medical Center, Bethesda, Maryland
• Chairman, American Optometric Association New Technology Committee
andrewmorgenstern@gmail.com
• Financial disclosure: none acknowledged
• Opinions expressed by Dr. Morgenstern in this column are his own and do not represent the opinion of the US government, Department of Defense, Veterans Administration or any other US governmental agency

Aaron Tarbett, OD, FAAO
• Served as the White House Optometry Consultant during the Bush and Obama administrations and chief of optometry at the Walter Reed Army Medical Center, Washington, DC
• On staff at the Hefner VA Medical Center in Salisbury, North Carolina.
atarbett@hotmail.com
• Financial disclosure: none acknowledged