June 15, 2005.
A local professor is developing a technology that could some day help restore vision in people who have lost their sight.
Laxman Saggere, an assistant professor of mechanical engineering at the University of Illinois at Chicago, is developing miniature, light-sensitive pumps that can squirt chemicals to stimulate the surviving cells of a diseased retina.
The goal is to combat blindness caused by diseases of photoreceptors in the retina. Age-related macular degeneration and retinitis pigmentosa affect more than 10 million people in the United States.
A person loses eyesight when photoreceptor cells in the retina get diseased and there is nothing left to absorb light. So far, no reversal is possible.
Healthy photoreceptor cells perform three tasks: They handle low light, manage color and vision resolution, and convert what the eye sees into a chemical signal that is transmitted to the brain. The brain interprets the signal as an image.
Saggere believes the answer lies in an approach that mimics the function of healthy photoreceptors by exploiting MEMS -- micro-electromechanical systems -- or microsystems technology. The technology enables miniature mechanical and electrical components to work as miniature machines on a chip.
His work calls for eventually implanting in a blind person's eye a chip made up of several tiny fluid-dispensing micro-pumps with droplet-size reservoirs. The reservoirs would encapsulate chemicals, called neurotransmitters, that transmit vision signals. Each micro- pump would power itself, wirelessly, by absorbing the light falling on the retina via a tiny integrated solar cell.
The pump would squirt the neurotransmitters onto the diseased retinas. The result would be a function that could substitute for natural photoreceptors lost to disease.
Saggere is using a $400,000 grant he won as part of the National Science Foundation's CAREER award to help turn his idea into a reality. The award recognizes early career development.
The technology isn't expected to be ready for animal experimentation for another four to five years.
The biggest hurdles involve the tiny scale of the device and its performance requirements.
It won't be easy to manufacture the tiny pumps, convert teensy amounts of light energy falling on the retina into useful power, and work with such miniscule amounts of chemicals.
Another obstacle is ensuring that the device would be biologically compatible with the human eye.
Saggere's approach differs from a more commonplace approach of stimulating cells using electrical current, which many rival researchers are pursuing.
For example, the Artificial Retina Project, a collaboration of several universities and laboratories, seeks to implant a chip comprising tiny electrodes in the blind person's eye. The patient would wear specially outfitted glasses and a microcomputer.
A tiny video camera would capture the signals in the eyeglasses of the blind person. The microcomputer would process the signals, and transform them into electrical current at the electrodes, which stimulate the retina's surviving cells.
Saggere doesn't hope to outrace the researchers pursuing the electrode technology for an artificial retina, which has already been implanted in several people for clinical trials. But he's wasting no time.
He has started working with a retina specialist and a UIC neuroscientist in bioengineering to push his concept.
Saggere believes his approach would be the ideal way to restore vision. The micro-pump chip can be designed to store different types of neurotransmitters to stimulate different types of cells in the retina. It requires no batteries and wouldn't generate heat or electrochemical reactions.
The MEMS technology has already revolutionized biomedical applications, including "lab-on-a-chip" technology, which enables doctors to diagnose infectious diseases and analyze biopsy samples in their offices without sending out for lab tests.
The implantable micro-pump technology could, in theory, be applied one day to deliver drugs at the optimal time and concentration exactly where they are needed. That could mean targeting dopamine in the brains of people suffering from Parkinson's disease, for example.
Source URL: http://www.suntimes.com/output/zinescene/cst-fin-ecol15.html.
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