Tuesday, April 22, 2008
Argus II Retinal Prosthesis Implanted Into First Two Patients in Europe
Times Online is reporting that Alfred Mann's 2nd Sight Medical has enrolled two patients from the UK into a clinical trial of the company's 60 electrode array Argus II Retinal Prosthesis System, a device covered by us on many occasions before (see flashbacks below). These enrollments are a part of the European leg of 2nd Sight's phase I clinical trial for the Argus II Retinal Implant, announced back in February.
From the Times Online:
Linda Moorfoot is one of a few American patients to be fitted with the current version of the implant. She had been totally blind for more than a decade with the inherited condition retinitis pigmentosa.But, with the aid of the camera mounted on a pair of sunglasses, she can now see a rough image of the world made up of light and dark blocks.
She told Sky News: "When I go to the grandkids' hockey game or soccer game I can see which direction the game is moving in. I can shoot baskets with my grandson, and I can see my granddaughter dancing across the stage. It's wonderful."Ms Moorfoot's implant has just 16 electrodes but the US surgeons have helped to fit an even more advanced device to the two British patients.
The updated model has 60 electrodes to give a clearer image. Meanwhile in California, scientists are developing an implant with 1,000 electrodes, which should allow facial recognition.
More at the Times Online...
Flashbacks: Second Sight Medical Retinal Prosthesis Receives FDA Approval for Clinical Trials ; Second Sight Implant: Positive Results Reported in the Study; Diamond Coating for Second Sight Implant
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Wednesday, April 16, 2008
Sensimed Technology: Noninvasive Intraocular Pressure Monitoring with a Contact Lens
Red Herring 100 awards for the best startups in Europe in 2008 have been announced. Only two (!) companies in biomed categories have been recognized by Red Herring: Israel-based Foamix and a Swiss company Sensimed AG, a firm trying to commercialize a noninvasive intraocular pressure monitor with a sensing contact lens.
Here's how the company outlines its technology:
We propose a novel approach to intraocular pressure (IOP) measurement allowing 24-hour continuous IOP monitoring, regardless of patient position and activities. The key element of this innovative measurement method is a soft disposable contact lens with a MEMS sensor embedded - the CLS - allowing the measurement of the cornea deformation due to IOP changes. As the system is placed in the same way as a corrective contact lens, no anaesthesia is required and patient vision remain almost unimpaired. A telemetry microprocessor and an antenna are also embedded into the CLS for wireless power and data transfer.CLS System
The CLS System comprises a pair of glasses (or patch for overnight measurements) and a pocket unit - the CLS Reader. Thru the glasses energy is sent to the CLS and data are retrieved wirelessly and stored in the pocket unit to be worn by the patient elsewhere.
The company has been around since at least 2004, so we are not really sure what was the reason for Red Herring to select it now. On the other hand, the company had almost a €4.8 million venture capital infusion in January, so things are not as static as they might appear to be.
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Monday, April 14, 2008
TONO-PEN AVIA Tonometer Gets MDEA Award
Tono-Pen Avia applanation tonometer, a device designed to diagnose glaucoma and other intraocular pressure disorders, is another winner of this year's Medical Design Excellence Awards. Reichert Inc., a Depew, NY firm behind the device, explains the benefits of its hand-held instrument:
No CalibrationThe TONO-PEN AVIA does not require daily calibration.
Accurate and Easy to Use
The TONO-PEN AVIA is designed to help eliminate operator error and functions in any position, making it ideal to use on all your patients, including those in beds or wheelchairs. Activated by the push of a button, the IOP measurement is displayed on two large, easy-to-read, LCD screens. Patients will appreciate the quick and gentle measurement process.
Intelligent
The TONO-PEN AVIA utilizes micro strain gauge technology and a 1.0mm transducer tip. The device displays the average of 10 independent readings along with a statistical confidence indicator, ensuring accurate, repeatable, and reliable tonometry results.
Versatile
The TONO-PEN AVIA tonometer features the same proven accuracy as the clinically trusted TONO-PEN XL, but with a more ergonomic design, four times longer lasting battery, and larger LCD screens. The proven reliability of Reichert's applanation tonometers allows operators to take IOP measurements confidently anytime, anywhere, and in any position.
Product page: TONO-PEN AVIA Applanation Tonometer...
Press release: 33 Innovative Products Win Medical Design Excellence Awards...
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Tuesday, March 25, 2008
Diaton Tonometer Approved in Canada
BiCOM, Inc., a Long Beach, NY company that we have covered before, is reporting that its hand-held transpalpebral (through the eyelid) tonometer, designed for the diagnosis of glaucoma, has now been approved for marketing in Canada. Health Canada's approval will now complement USA FDA and CE MARK clearances. Given the fact that glaucoma is often painless and very devastating, one can only hope that this device will find widespread use not only in ophthalmologist offices, but also in primary care clinics and such.
From the press release:
Diaton tonometry - a new trans-palpebral and trans-scleral methodology has received the Gold Medal at the International Exhibition of Research and new Technology in Geneva & the Gold Medal at the International Exhibition of Innovation Research and New Technology - "Brussels Eureca".Portability, safety and simplicity make Tonometer Diaton ideal for a wide range of applications: for mass glaucoma screening of the population, at the patient's bedside, in geriatrics homes, in children hospitals, for the military and for home use.
Diaton Tonometer is intended for use by Inpatient & Outpatient Clinics such as Hospitals, Emergency Rooms, Nursing & Elderly Homes, General & Specialty Practitioners as well as Ophthalmologists and Optometrists.
Tonometer Diaton is the ideal solution in the following cases when the use of other devices is problematic or impossible:
mass prophylactic screening of patients;
IOP control during clinical observation of glaucoma patients;
ortoclinostatical probe, as an additional test to diagnose glaucoma and during select the adequate hypotensive therapy;
ophthalmotone monitoring (even at night time);
IOP measuring during contact correction (lenses are not taken out),
IOP measuring in immobilized patients;
IOP measuring in children.
on patients with the following conditions: chronic conjunctivitis, cornea pathology, including keratitis, keratotone, cornea dimness, after penetrating keratoplastics, keratoprosthesis, laser refractive correction of the eyesight, high degree of ametropy, astigmatism;
on patients with medicinal allergies;
Lasik/ PRK (recent clinical trials have proved that Diaton is the only device that can be used for IOP measurement right after these surgeries) Diaton tonometer is a perfect device for mass screenings for glaucoma for any age group. Undiagnosed and untreated, glaucoma can cause blindness. Glaucoma is the leading cause of blindness in all age groups - from babies to senior citizens. Everyone needs to get diagnosed to preserve eyesight.
Product page: Diaton Tonometer...
Press release: BiCOM Obtains Health Canada Approval for Tonometer Diaton, Unique Glaucoma Eye Test Through Eyelid...
Flashback: Tonometry Through The Eyelid
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Monday, March 17, 2008
Optical Coherence Tomography from Bioptigen Gets Award
Optical coherence tomography (OCT), a technology often described as combining the principles of ultrasound with the imaging performance of a microscope, is thought to be particularly useful for future diagnostic devices for ophthalmology. In essence, OCT is a technique that allows the reconstruction of tissue microstructure, based on tomographic images obtained with low intensity light. Bioptigen, Inc., a Duke University spin out, has been recognized with the Frost & Sullivan 2008 North American Excellence in Research Award for its work in implementing OCT for ophthalmic applications. The company believes that its technology one day will provide a very early look at quite a few diseases of the eye and nervous system.
Bioptigen's SDOCT systems enable researchers and clinicians to resolve the microstructure of the retina in finest detail, including the nerve fiber layer, inner and outer plexiforms, retinal pigment epithelium layers, Bruch's membrane, and vessels of the choriocapillaris. Additionally, the tissue structures of the cornea, conjunctiva, and sclera can also be clearly visualized with a mere change in focal position and no change in optical irradiance.The software suite works in tandem with the scanners and SDOCT engine to offer intuitive and flexible system control with advanced functionality. Real-time acquisition and display, combined with customizable, protocol-driven operations, help ensure maximum workflow efficiency. Volume intensity projections generate en-face images (similar to the fundus images taken of the retina) that enable accurate cross-sectional image registration. Doppler processing quantifies system dynamics and flows.
Optical Coherence Tomography technology page at Bioptigen...
Product page: High Throughput High Resolution Biomedical Imaging from Bioptigen, Inc...
Flashbacks: Optical Coherence Tomography for Multiple Sclerosis; FDA Approves Optical Coherence Tomography (OCT) ; Optical Coherence Tomography System by Imalux; Optical Coherence Tomography: Positive Results in Clinical Study Reported.
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Wednesday, March 12, 2008
Epi-Ret Retinal Implant
At Aachen University Clinic and the Fraunhofer Institute for Microelectronic Circuits in Germany, scientists are developing an epiretinal implant for people suffering from retinitis pigmentosa, reports EETimes. (Epiretinal means the prosthesis is placed on the surface of a patient's damaged retina.) The device, capable of displaying images to the patient, was designed to receive both the video signal and the electricity necessary to power the implant wirelessly.
From EETimes:
Presently, the device is equipped with 25 stimulating electrodes that are connected with ganglion cells. While the researchers admit that this is far from providing an actual eyesight experience, test persons said they were able to "see" electronically generated patterns or a coarse impression of the images they received.The technology also helps eye specialist to simplify the implantation of such devices into the human eye. In comparison to wire-bound implants, the wireless device is much easier to implant into the eye and to wear, the university clinic said.
More details from the project page at RWTH Aachen University:
About 3 million people worldwide suffer from retinitis pigmentosa, making this one of the leading causes for blindness. In retinitis pigmentosa patients a slow and progressive degeneration of photoreceptors is observed, while about 30% of the retina's ganglion cells remain intact. These ganglion cells are connected to the visual cortex of the brain via the optic nerve. Hence electrical stimulation of the remaining intact ganglion cells by placing micro electrodes onto the retina can in principal lead to visual sensation.The idea is that the patient wears a pair of glasses which have an integrated CMOS camera. An image of the environment is taken and processed by a digital signal processor (the so-called retina encoder), which calculates a stimulation pattern for the electrodes placed onto the retina that reproduces the original image. Data and energy are then transferred via RF coupling to the implant inside the patient's eye. Here a silicon chip generates bipolar current pulses that stimulate the intact ganglion cells of the retina via three-dimensional micro electrodes.
More from EETimes...
Those of you that are interested in the latest state of affairs in the world of retinal prostheses, should check out this excellent review at R&D Magazine, or look over Medgadget's retinal prostheses archives.
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Thursday, March 6, 2008
New Metabolic Technique for Early Detection of Eye Diesease
Ophthalmologist Victor M. Elner, MD, PhD and colleagues at the University of Michigan developed a new diagnostic technique that allows early detection and monitoring of retinal and optic nerve diseases well before patients develop clinical signs and symptoms. According to the researchers, their technique can detect signs of intracellular metabolic stress that "occurs at disease onset and causes altered flavoprotein redox activity that increases flavoprotein autofluorescence (FA)."
University of Michigan press office explains:
The study grew out of Petty and Elner’s observation that metabolic stress at the onset of disease causes certain proteins to become fluorescent. To measure the intensity of this flavoprotein autofluorescence (FA), they designed a unique imaging system equipped with state-of-the art cameras, filters, and electronic switching, together with customized imaging software and a computer interface.Petty, a biophysicist and expert in imaging, explains why FA data is a good predictor of disease. “Autofluorescence occurs when retinal cells begin to die, often the first event in diseases like glaucoma and diabetic retinopathy,” he says. “Cell death can be observed microscopically, but not as yet though any current imaging methods. We believe this study is a big step forward toward creating a diagnostic tool that can characterize disease long before symptoms or visible signs appear.”
The women in the study were newly diagnosed with PTC and had not yet received treatment. According to standard tests they had good visual acuity, and their visual field tests indicated either subtle abnormalities or none at all. Visual field testing, used to measure the area seen by the eye, is a standard tool for evaluating eye diseases such as glaucoma.
After the standard vision tests were administered, the researchers measured FA values for the six women and the age-matched control group. All of the patients with PTC had higher FA values in the eye that was more severely affected. In fact, FA values averaged 60% greater in the more affected eye of these women. By contrast, the control group had no significant difference in FA values between their healthy eyes.
The researchers also found that FA data more accurately described the different degree of disease in each eye for a given patient, as compared to the standard vision tests.
Elner, who is an ophthalmologist and a pathologist, says that the ability to detect subtle distinctions is important. “Early treatment for eye disease is so important, and this study suggests that FA activity is a very good indicator of eye disease,” he says. “Cardiologists have long used blood pressure testing to head off heart disease. We believe that FA testing will likewise be a helpful diagnostic tool for eye doctors looking to prevent blindness.”
Press release: A device that measures metabolic stress could help eye doctors diagnose disease before symptoms appear...
Abstract: Flavoprotein Autofluorescence Detection of Early Ocular Dysfunction Arch Ophthalmol. 2008;126(2):259-260.
More from MIT Tech Review...
Image credit: Wellcome Images: Structure of the eye...
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Thursday, January 24, 2008
Bionic Eye With Blind in Mind
Biomedical engineers at University of Southern California have been working on a design, and filed for a patent, for a video camera to be implanted directly into the eye as a prosthesis to help with vision problems such as macular degeneration:
The eye's lens normally projects an image onto a curved surface called the retina at the back of the eye. This creates problems for light-sensitive chips since they have to be flat.One way around this is to use a camera outside the eye to record images and send them via a wire to the chip at the back of the eye.
But Michelle Hauer, an optical engineer at the University of Southern California, Los Angeles, US, says a better idea is to implant the camera directly within the eye, but avoiding the retina.
She and colleagues have come up with a design that is small enough to be implanted within the lens of the eye, and takes into account the effect of the cornea on incoming light.
The device transmits images to a chip at the back of the eye, which passes the image signals on to the nerve cells.
With bionic eyes, overpowering prosthetic legs, dangerously strong mechanical arms, and machines that make old Japanese men strong, we predict people will soon be wanting replacements for their originals.
(hat tip: Engadget)
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Tuesday, January 22, 2008
PASCAL Photocoagulation System
PASCAL (Pattern Scan Laser) Photocoagulator, a system designed for the treatment of retinal diseases such as proliferative diabetic retinopathy, is a product of OptiMedica Corp., a Santa Clara, California company. The device has been given the gold medal at the 2007 Medical Design Excellence Awards.
The PASCAL technology platform is based upon the use of a proprietary, semi-automated, pattern generation method employing short 532 nm laser pulses. These laser pulses are delivered in a rapid predetermined sequence resulting in improved precision, safety, patient comfort, and a significant reduction in treatment time compared with single-spot photocoagulation.Pre-clinical animal studies, as well as initial pilot studies in humans indicate that in addition to reducing treatment duration for typical patients with proliferative diabetic retinopathy, the number of sessions may also be reduced.
This fully integrated system incorporates design advancements including:
Intuitive touch screen user interface
Pattern scanner technology
Advanced optics slit lamp
Slit lamp mounted micromanipulator
Dual slit lamp mounted rotary power controls
PrecisionSpot™ laser delivery
LIO compatible
Wheelchair accessible table
Ergonomic features for physician and patient
Product page: PASCAL Pattern Scan Laser...
More about PASCAL: PASCAL Fundus Images ...; PASCAL Treatment Videos ...; System Simulation ...
MDEA Surgical Equipment, Instruments, and Supplies Winners...
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Thursday, January 17, 2008
Electronic Contact Lenses for Better Vision
Researchers at the University of Washington managed to embed an electronic circuit and LEDs directly into contact lenses, which seemed to look good on rabbit eyes. Though the circuit is not functional and the lights don't light up, the development shows that future applications like direct video to the eye may indeed be possible.
The prototype device contains an electric circuit as well as red light-emitting diodes for a display, though it does not yet light up. The lenses were tested on rabbits for up to 20 minutes and the animals showed no adverse effects.Ideally, installing or removing the bionic eye would be as easy as popping a contact lens in or out, and once installed the wearer would barely know the gadget was there, Parviz said. [Babak Parviz is a University of Washington assistant professor of electrical engineering --ed.]
Building the lenses was a challenge because materials that are safe for use in the body, such as the flexible organic materials used in contact lenses, are delicate. Manufacturing electrical circuits, however, involves inorganic materials, scorching temperatures and toxic chemicals. Researchers built the circuits from layers of metal only a few nanometers thick, about one thousandth the width of a human hair, and constructed light-emitting diodes one third of a millimeter across. They then sprinkled the grayish powder of electrical components onto a sheet of flexible plastic. The shape of each tiny component dictates which piece it can attach to, a microfabrication technique known as self-assembly. Capillary forces -- the same type of forces that make water move up a plant's roots, and that cause the edge of a glass of water to curve upward -- pull the pieces into position.The prototype contact lens does not correct the wearer's vision, but the technique could be used on a corrective lens, Parviz said. And all the gadgetry won't obstruct a person's view.
"There is a large area outside of the transparent part of the eye that we can use for placing instrumentation," Parviz said. Future improvements will add wireless communication to and from the lens. The researchers hope to power the whole system using a combination of radio-frequency power and solar cells placed on the lens, Parviz said.
Press release: Contact lenses with circuits, lights a possible platform for superhuman vision
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Wednesday, January 2, 2008
Presenting: The Hello Kitty Contact Lenses
Finally, for those in the audience that have been waiting for them, the Hello Kitty contact lenses are here.
Outrage at Hello Kitty Hell...
(hat tip: BoingBoing)
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Monday, November 19, 2007
The Fight Is On for Drug That Lengthens Eyelashes
Bimatoprost, a medication for glaucoma from Allergan, Inc., has this interesting warning in its product insert:
LUMIGAN® (bimatoprost ophthalmic solution) 0.03% has been reported to cause changes to pigmented tissues. The most frequently reported changes have been increased pigmentation of the iris, periorbital tissue (eyelid) and eyelashes, and growth of eyelashes. (emphasis ours)
It turns out that some companies (including Allergan itself) are trying to capitalize on the eyelash-inducing side effect of bimatoprost, and are working on developing preparations to make women and men more attractive, without the mascara.
The Wall Street Journal has an eye opening article, featuring Allergan, cosmetics companies, the FDA, a federal raid, and billions of dollars at stake...
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Friday, November 16, 2007
FusionOptic™ Technology from Leica
We've seen quite a few devices that are designed to improve all sorts of neurologic functions. However, we've never seen a medical gadget that is designed to utilize normal human neurology for improvement of its own function. And that is what FusionOptic™ Technology from Leica is supposedly doing: increasing the resolution of stereomicroscopes, models M205 C and M165 C, by delivering two different images to each eye.
From the press release about Leica M205 C, a model just introduced at the Medica 2007 in Düsseldorf (shown above; M165 C model is shown below).
The new Leica M205 C breaks through the previous optical resolution limits of stereomicroscopy by incorporating Leica's new FusionOptic™ technology (patent pending) which takes advantage of a neurological phenomenon. The left beam path produces great depth of field, while the right beam path provides a high-resolution image. The human brain then combines the best information from both channels to compose an image whose resolution and depth of field have never been achieved in any stereomicroscope before. The Leica M205 C is the world's first stereomicroscope with a fully apochromatically corrected 20.5:1 zoom. In the zoom range from 0.78x to 16x, the resolution increases continuously up to 1050 lp/mm (planapochromat objective 2x). Due to the natural laws of optics, this performance class has never been seen before in stereomicroscopes.
The high-end surgical microscope Leica M525 OH4 offers 36% more reach than comparable instruments. Another remarkable feature is its precise, harmoniously balanced yet easy movement. The combination of Leica OptiChrome™ optics, 300 watt xenon illumination and fully automatic lamp changer ensures high-contrast images with great field depth. The AutoIris™ feature prevents overheating of the tissue outside the field of view. The Leica BrightCare™ feature automatically regulates the light to the optimum intensity. The combination of the Leica M525 microscope and the compact stand F40 is particularly suitable for ENT and spine specialists, offering an excellent view, easy maneuverability, optimal stability and a convincing price-performance ratio.
Product pages: Leica M205 C ...; Leica M165 C ...
Press releases: Revolutionary Stereomicroscopes, New Research and Diagnosis Microscopes and Microscope Systems for Microsurgery ...; Revolutionary Stereomicroscopy and Unique Precision Instrument for Surface Preparation ...
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Tuesday, November 6, 2007
Developing Corneas from Sea Cucumbers
Each year thousands of patients require cornea transplants to restore their vision due to either disease or trauma. Now Garrett Matthews, Assistant Professor of Physics at University of North Carolina, hopes to help people "sea" better using sea cucumbers (BAD pun intended).
When a person's cornea - the transparent surface layer at the front of the eye - becomes damaged, it can be replaced using tissue from an organ donor. But there is a big shortage of corneal donors, as there are for every other type of organ.An ideal solution would be to develop an artificial cornea, but is has proved very hard to design and manufacture a structure so that it is optically clear in the middle and biocompatible at the edges.
Now Garret Matthews, a biophysicist at the University of South Florida in Tampa, US, and his colleagues have come up with a design for artificial corneas that they say achieves this - using sea cucumbers.
Sea cucumbers are sausage-shaped echinoderms, most species of which live on the sea floor in a variety of marine environments around of the globe.
The team's artificial cornea is made from tiny collagen fibres extracted from these sea cucumbers. When placed in a centrifuge, the fibres self assemble into layers in which the fibres are aligned vertically, a structure that is very similar to the tissue in mammalian corneas. The result is a thin layer of material that is transparent and biocompatible, as well as cheap and easy to make, says the team.
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Friday, October 26, 2007
Scientists Discover New Retinal Cell; Promise of Artificial Retinas
A collaborative project between high-energy physicists from the University of California, Santa Cruz, and neuroscientists from the Salk Institute in La Jolla, CA., has resulted in a discovery of a novel type of retinal cell dubbed the "upsilon cell." Furthermore, the investigators believe that they can apply superdense silicon array electrodes used in the research to develop next-generation artificial retinas:
The cell type has very similar properties to so-called Y retinal ganglion cells, which were first described in cats in 1966. Upon the Y-cell's discovery, scientists began a decades-long search for its counterpart in primates. The UCSC-Salk Institute team named the new cell type the upsilon cell, after the Greek uppercase letter written as "Y."This week's discovery puts scientists one step closer to understanding how primates transform the chaos of light bombarding their eyes into a clear, steady, color picture of the world around them.
"This has been a fantastic journey through high-energy physics, neurobiology, technology, and human health," said senior author Alan Litke, adjunct professor of physics at UCSC's Santa Cruz Institute for Particle Physics (SCIPP). "We started out developing instruments to look for fundamental particles such as the top quark and the Higgs boson. Then we realized we could apply some of those technological concepts to studying neural systems. Now we are using the new technology for experiments that will help guide the design of future retinal prosthetic devices."
The retina is the paper-thin coating on the back of the eye that turns light into coded messages headed to the brain. The first step in the process is handled by rod and cone cells that transform arriving photons of light into electrical signals. Another three cell layers process those signals and then pass them on to ganglion cells like the Y and upsilon, which are middlemen that collate the signals and send them up the optic nerve to the brain. The eye has only about one retinal ganglion cell for every 100 rod and cone cells. Although biologists have identified at least 22 distinct types of primate retinal ganglion cells, the functions of only about a half-dozen of them are known...
The upsilon cells went undetected for so long, Litke suggested, mainly because they are only a tiny fraction of all the ganglion cells. This small number makes the cells very difficult to detect with traditional physiological techniques, which typically monitor only one cell or a tiny patch of retina at any one time.
So Litke and his colleagues developed a new detection system inspired by their research detecting particles in high-energy-physics collisions. The device crammed 512 electrodes into an area of 1.7 square millimeters (about the size of a pinhead). Each of the team's experiments, conducted in the Salk Institute lab of neurobiologist E. J. Chichilnisky, recorded the electrical activity of more than 250 cells simultaneously, five to 10 of which were upsilon cells.
"The high density and large number of the electrodes gave us the ability to pick out individual neurons and at the same time examine a whole collection of cells," Litke said. "If you had only a few electrodes, you might detect a single cell with unusual properties, but you wouldn't know what to do with it--it might just be a sick cell. Now we can identify a significant number of these cells in a single preparation, all with the same properties. That gives us confidence in our results."
To figure out how the upsilon cells handle information, the researchers projected simple movies through a microscope lens and onto a patch of retina. As rod and cone cells picked up the images, they sent electrical signals to a wide variety of retinal nerve cells. After picking up the signals on the electrode array, SCIPP postgraduate researcher Dumitru Petrusca matched them with the movie, allowing him to map out the light-sensitive regions of each cell. The team found that the collection of upsilon cells forms a mosaic across the retina, with nearly continuous coverage and very little overlap.
The sensitive regions of upsilon cells measured 300 to 500 microns across, considerably larger than most other retinal ganglion cells (a micron is one-millionth of a meter; 300 microns is about three times the width of a human hair). Upsilon cells showed particular sensitivity to oscillating fields of stripes, the sort of input they might receive when a textured surface moves across their field of view.
Together, these qualities suggest an ability to sense motion. Amid a flood of information heading to the brain, sensitivity to changing patterns would emphasize the parts of the picture that are moving. And the large size of the cell's sensitive region would be better suited to sensing motion than providing pinpoint resolution on a stationary object.
If the upsilon cells prove to be connected to the brain the way cat Y-cells are, then they likely feed their information to two separate processing centers. One, called the lateral geniculate nucleus, is a waystation to the visual cortex. The other, the superior colliculus, helps turn the eyes and the head toward a stimulus. Litke said this would strengthen the suggestion that the upsilon cells help detect motion.
"You see something coming in your peripheral vision, and you turn your head because maybe it's a lion coming to attack you," he said.
With their 512-electrode array, Litke and his colleagues are planning to keep on filling in the blanks of other unknowns. "We're working on many other cell types," Litke said. "This is just the tip of the iceberg."
Press release: Discovery of retinal cell type ends four-decade search ...
More from MIT Tech Review...
More about The Retinal Readout Project ...
Flashbacks: Medgadget artificial retina archives..
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Thursday, October 18, 2007
Optical Coherence Tomography for Multiple Sclerosis
A group of investigators from Johns Hopkins studied 40 multiple sclerosis (MS) patients with optical coherence tomography (OCT) of the eye (see flashbacks below about the technology), and found that this technique offers a potentially new, cost-effective way to diagnose and monitor the progression of the disease:
The process, which uses a desktop machine similar to a slit-lamp, is simple and painless. The retinal nerve fiber layer is the one part of the brain where nerve cells are not covered with the fat and protein sheathing called myelin, making this assessment specific for nerve damage as opposed to brain MRI changes, which reflect an array of different types of tissue processes in the brain.Results of the scans were calibrated using accepted norms for retinal fiber thickness and then compared to an MRI of each of the patient's brains - also calibrated using accepted norms. Experimenters found a correlation coefficient of 0.46, after accounting for age differences. Correlation coefficients represent how closely two variables are related -- in this case MRI of the brain and OCT scans. Correlation coefficients range from -1 (a perfect opposing correlation) through 0 (no correlation) to +1 (a perfect positive correlation). In a subset of patients with relapsing remitting MS, the most common form of the disease, the correlation coefficient jumped to 0.69, suggesting an even stronger association between the retinal measurement and brain atrophy.
"This is an encouraging result," says Johns Hopkins neurologist Peter Calabresi, M.D., lead author of the study, which appears in the October 2007 issue of Neurology. "MRI is an imperfect tool that measures the result of many types of tissue loss rather than specifically nerve damage itself. With OCT we can see exactly how healthy these nerves are, potentially in advance of other symptoms."
In addition, says Calabresi, OCT scans take roughly one-tenth as long and cost one-tenth as much as the MRI, which means they are faster and cheaper to use in studies that track the effectiveness of new treatments for MS.
Press release: SIMPLE EYE SCAN OPENS WINDOW TO MULTIPLE SCLEROSIS ...
Flashbacks: FDA Approves Optical Coherence Tomography (OCT) ; Optical Coherence Tomography System by Imalux; Optical Coherence Tomography: Positive Results in Clinical Study Reported.
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Wednesday, October 10, 2007
Auto Blinkers for The Eyes
Scientists from the University of Pittsburgh filed a patent application for a pair glasses that monitor and auto trigger the eyelid to blink. The device one day might become useful for people with central and peripheral neurological damage, who have either absent or diminished eye-blink reflex..
From the abstract attached to the patent application:
The method includes determining whether the functional muscle has contracted, generating a contraction signal if it is determined that it has contracted, and causing the denervated muscle to contract following the generation of the contraction signal. Also, an apparatus for stimulating such a subject including one or more sensing devices operatively associated with the functional muscle and one or more stimulating devices operatively associated with the denervated muscle. One or more of the sensing devices generates one or more first signals in response to activity indicating functional muscle contraction. The one or more stimulating devices are made to cause the denervated muscle to contract in response to the generation of the first signals.
Patent Application for METHOD AND APPARATUS FOR STIMULATING A DENERVATED MUSCLE...
(Hat tip: Sci Fi Tech)
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Wednesday, October 3, 2007
Artificial Corneas from Fraunhofer Institute
German researchers have developed an artificial cornea that promises easy integration with a patient's native cornea, and prevents cellular hyperplasia on its plastic surface:
"Our artificial corneas are based on a commercially available polymer which absorbs no water and allows no cells to grow on it," says IAP project manager Dr. Joachim Storsberg. "Once our partner Dr. Schmidt Intraokularlinsen GmbH has suitably shaped the polymers, we selectively coat the implants: We lay masks on them and apply a special protein to the edge of the cornea, which the cells of the natural cornea can latch onto. In this way, the cornea implant can firmly connect with the natural part of the cornea, while the center remains free of cells and therefore clear." What is special about this protein is that it can survive the later thermal sterilization of the artificial cornea without being damaged, as it does not have the three-dimensional structure typical of large proteins. Such a structure would be destroyed during the sterilization process, leading to changes in the material's properties. The optical front part of the implant is coated with a hydrophilic polymer, so that it is constantly moistened with tear fluid.Researchers in Dr. Karin Kobuch's working group at Regensburg University Hospital have already tested these corneas in the laboratory and found that their cells graft very well at the edge and cease growing where the coating stops. The optical center of the implant thus remains clear. The first implants have already been tested in rabbits' eyes - with promising results. If further tests are successful, the technology will be tried on humans in 2008.
More from Fraunhofer Institute for Applied Polymer Research IAP in Potsdam...
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