A team of ophthalmologists, led by the Jacobs Retina Center Director Dr. William Freeman, partners with Nanovision Biosciences and UCSD to develop an artificial retina.

Links: Full Paper, UCSD News Press Release

New Nano-Implant Could One Day Help Restore Sight

With high-resolution retinal prosthesis built from nanowires and wireless electronics, engineers are one step closer to restoring neurons’ ability to respond to light

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Scanning electron micrograph (SEM) image of individual nanowires and groupies of nanowires. Each wire can produce an electric current when hit by light.

A team of engineers at the University of California San Diego and La Jolla-based startup Nanovision Biosciences Inc. have developed the nanotechnology and wireless electronics for a new type of retinal prosthesis that brings research a step closer to restoring the ability of neurons in the retina to respond to light. The researchers demonstrated this response to light in a rat retina interfacing with a prototype of the device in vitro.

They detail their work in a recent issue of the Journal of Neural Engineering. The technology could help tens of millions of people worldwide suffering from neurodegenerative diseases that affect eyesight, including macular degeneration, retinitis pigmentosa and loss of vision due to diabetes.

Despite tremendous advances in the development of retinal prostheses over the past two decades, the performance of devices currently on the market to help the blind regain functional vision is still severely limited—well under the acuity threshold of 20/200 that defines legal blindness.

“We want to create a new class of devices with drastically improved capabilities to help people with impaired vision,” said Gabriel A. Silva, one of the senior authors of the work and professor in bioengineering and ophthalmology at UC San Diego. Silva also is one of the original founders of Nanovision.

The new prosthesis relies on two groundbreaking technologies. One consists of arrays of silicon nanowires that simultaneously sense light and electrically stimulate the retina accordingly. The nanowires give the prosthesis higher resolution than anything achieved by other devices—closer to the dense spacing of photoreceptors in the human retina. The other breakthrough is a wireless device that can transmit power and data to the nanowires over the same wireless link at record speed and energy efficiency.

One of the main differences between the researchers’ prototype and existing retinal prostheses is that the new system does not require a vision sensor outside of the eye to capture a visual scene and then transform it into alternating signals to sequentially stimulate retinal neurons. Instead, the silicon nanowires mimic the retina’s light-sensing cones and rods to directly stimulate retinal cells. Nanowires are bundled into a grid of electrodes, directly activated by light and powered by a single wireless electrical signal. This direct and local translation of incident light into electrical stimulation makes for a much simpler—and scalable—architecture for the prosthesis.

The power provided to the nanowires from the single wireless electrical signal gives the light-activated electrodes their high sensitivity while also controlling the timing of stimulation.

“To restore functional vision, it is critical that the neural interface matches the resolution and sensitivity of the human retina,” said Gert Cauwenberghs, a professor of bioengineering at the Jacobs School of Engineering at UC San Diego and the paper’s senior author.

Wireless telemetry system

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Primary cortical neurons cultured on the surface of an array of optoelectronic nanowires. Note the extensive neurite outgrowth and network formation.

Power is delivered wirelessly, from outside the body to the implant, through an inductive powering telemetry system developed by a team led by Cauwenberghs.

The device is highly energy efficient because it minimizes energy losses in wireless power and data transmission and in the stimulation process, recycling electrostatic energy circulating within the inductive resonant tank, and between capacitance on the electrodes and the resonant tank. Up to 90 percent of the energy transmitted is actually delivered and used for stimulation, which means less RF wireless power emitting radiation in the transmission, and less heating of the surrounding tissue from dissipated power.

The telemetry system is capable of transmitting both power and data over a single pair of inductive coils, one emitting from outside the body, and another on the receiving side in the eye. The link can send and receive one bit of data for every two cycles of the 13.56 megahertz RF signal; other two-coil systems need at least 5 cycles for every bit transmitted.

Proof-of-concept test

For proof-of-concept, the researchers inserted the wirelessly powered nanowire array beneath a transgenic rat retina with rhodopsin P23H knock-in retinal degeneration. The degenerated retina interfaced in vitro with a microelectrode array for recording extracellular neural action potentials (electrical “spikes” from neural activity).

The horizontal and bipolar neurons fired action potentials preferentially when the prosthesis was exposed to a combination of light and electrical potential—and were silent when either light or electrical bias was absent, confirming the light-activated and voltage-controlled responsivity of the nanowire array.

The wireless nanowire array device is the result of a collaboration between a multidisciplinary team led by Cauwenberghs, Silva and William R. Freeman, director of the Jacobs Retina Center at UC San Diego, UC San Diego electrical engineering professor Yu-Hwa Lo and Nanovision Biosciences.

A path to clinical translation

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Primary cortical neurons cultured on the surface of an array of optoelectronic nanowires. Here a neuron is pulling the nanowires, indicating the cell is doing well on this material.

Freeman, Silva and Scott Thorogood, have co-founded La Jolla-based Nanovision Biosciences, a partner in this study, to further develop and translate the technology into clinical use, with the goal of restoring functional vision in patients with severe retinal degeneration. Animal tests with the device are in progress, with clinical trials following.

“We have made rapid progress with the development of the world’s first nanoengineered retinal prosthesis as a result of the unique partnership we have developed with the team at UC San Diego,” said Thorogood, who is the CEO of Nanovision Biosciences.

Other authors are UC San Diego Jacobs School of Engineering current and former graduate and postdoctoral researchers Sohmyung Ha (now Assistant Professor at NYU Abu Dhabi), Massoud L Khraiche (now at Cbrite Inc.), Abraham Akinin, Yi Jing (now at Nanovision Biosciences), Samir Damle and Yanjin Kuang, as well as Sue Bauchner, Director of Engineering at Nanovision Biosciences.

The research was funded by Nanovision Biosciences, Qualcomm Inc. and the Institute of Engineering in Medicine and the Clinical and Translational Research Institute at UC San Diego.

 

 

Toy Story

“If it wasn’t for Bill, I would be walking around with a seeing eye dog right now.” – Yanofsky

Yanofsky

Peter Yanofsky, who runs WowWee’s U.S. operations in La Jolla, with the robot MiP. The new toy can be controlled with hand gestures or commands from smartphones. It can roll, dance and play games.

UC San Diego is learning that making money can be child’s play. For the first time, the university has licensed some of its technology to a well-known toymaker, which will use it to power and control a zippy-and-trippy little robot called MiP. WowWee, whose U.S. operations are based in La Jolla, has been logging a brisk pace of orders for the $99 toy, which will go on shelves at Best Buy starting in May. The University of California San Diego could earn about $1 million in tech-transfer fees on MiP, and more riches may follow. The school plans to help WowWee develop a half-dozen or so other products, hoping to create a fee-generating blockbuster in the nation’s $22 billion toy industry.

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UC San Diego Shiley Eye Institute Physician Honored with Day of Recognition

After more than 20 years of service to the San Diego community, William R. Freeman, M.D.,professor of ophthalmology at UC San Diego School of Medicine and Director of the UCSD Jacobs Retina Center adjacent to Shiley Eye Center, is being recognized by The Foundation Fighting Blindness as well as The City of San Diego.

On Wednesday, May 14, 2008, the Foundation Fighting Blindness (FFB) will honor Freeman with the Visionary Award at their inaugural San Diego Dining in the Dark. The Visionary Award celebrates extraordinary people and professionals who support efforts to find treatments and cures for vision loss, as well as individuals who have made a profound impact on their community.

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Clincal Trials Update

Director of the Joan and Irwin Jacobs Retina Center (JRC) and Professor of Ophthalmology William Freeman, M.D., and his team of physicians, scientists, and staff are currently conducting a number of clinical trials related to retinal diseases, such as Age Related Macular Degeneration (AMD), Retinal Vein Occlusion, and Diabetic Retinopathy.

These clinical trials are taking place in the new JRC adjoining the UCSD Shiley Eye Institute. The Jacobs Retina Center is home to specially designed labs and clinical evaluation facilities as well as staff and faculty who examine, evaluate, and assess patients or participants of clinical trials. The rooms are equipped with specialized charts and equipment that test not only basic reading and vision capabilities but also take into account factors like contrast sensitivity. For example, a patient may not see the “E” on the black-on-white chart, known as the Snellen visual acuity chart, but that patient may see the “E” on a chart that is different shades of gray-on-gray. In addition, there are many specialized instruments that measure retinal function and structure in non-invasive ways. These instruments allow the researchers to study the response of the retina to new treatments. Continue reading

Optical Coherence Topograhpy and its uses in gauging HIV retinal damage

Optical coherence tomography gauges HIV retinal damage

Updated: 2005-03-31 (Reuters Health)

By David Douglas

NEW YORK (Reuters Health) – Optical coherence tomography (OCT) is useful in assessing retinal nerve fiber layer (RNFL) thickness in HIV patients, who can develop visual problems in the absence of cytomegalovirus (CMV) retinitis.

By using OCT, senior investigator Dr. William R. Freeman told Reuters Health, “one can objectively measure the damage to the retina which appears to result in these vision losses in HIV patients without infections in the retina.”
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