Technique for Complete and Permanent Adherence of DSEK Disc to Host Corneal Stroma

0 comments

Posted on 21st October 2011 by Pacific ClearVision Institute in General

An informative video featuring Pacific ClearVision Institute’s Dr. Scott Cherne, of Eugene, Oregon, is welcomed by the World Ophthalmology Congress 2012.

The special feature accepted by the WOC demonstrates a technique for permanent and complete DSEK Disc Adherence.

The World Ophthalmology Congress is the longest continuous international medical meeting, and offers a unique opportunity to meet and network with a truly international audience and gain insight into the latest product information and trends in ophthalmology, which promises to be an ideal setting for scientific communication and innovation.

All of this leads to the end result of improving the eye health of communities around the world.

To view the esteemed video feature visit Pacific ClearVision Institute’s website at www.pcvi.com..

PCVI Eye Surgeons participate in Alcon sponsored Sodium Hyaluronate (Dry Eye) Study

0 comments

Posted on 10th October 2011 by Pacific ClearVision Institute in General

Doctors John DeGuire and Ryan Lapour, Eye Surgeon specialists at Pacific ClearVision Institute in Eugene, Oregon, are engaging in an ongoing Sodium Hyaluronate study in an effort to relieve dry eye symptoms.

An estimated 20 million people globally have dry eye, and more than 3.2 million American women, aged 50 or older, suffer from chronic dry eye.

Among dry eye patients over the age of 65 in the US, 73% visited their eye care professional within the previous year for their dry eye condition, and Restasis had over $1.5 billion in sales between 2003 to 2008.

The local community is allowed participation in this ALCON sponsored study.

Folks must meet the following critera:

1. Male and female adults aged 18 years and over.

2. Women should not plan to become pregnant during the course of the study. Women should plan to use adequate birth control methods for the duration of the study.

3. Patients must have at least a 3 month documented history of dry eye in both eyes diagnosed as dry eye syndrome, keratoconjunctivitis sicca (KCS), or due to Sjögren’s Syndrome (immune exocrinopathy).

4. Patients must have all of the following criteria in the same eye at both the Screening and Baseline visits: At least 2 symptoms of dry eye (soreness, scratchiness, dryness, grittiness, and burning)

5. Patients must agree to discontinue all artificial tears from Screening through the duration of the treatment period (Screening to Day 14).

6. Patients who have taken Restasis® are eligible for inclusion if they have not used Restasis during the 4 weeks prior to Screening.

For more information contact Pacific ClearVision Institute at 541-343-5000.

Biologists Use Sinatra-Named Fly to Show How to See the Blues — And the Greens

0 comments

Posted on 10th October 2011 by Pacific ClearVision Institute in General |Retina

New York University biologists have identified a new mechanism for regulating color vision by studying a mutant fly named after Frank (‘Ol Blue Eyes) Sinatra. Their findings, which appear in the journal Nature, focus on how the visual system functions in order to preserve the fidelity of color discrimination throughout the life of an organism. They also offer new insights into how genes controlling color detection are turned on and off.

Many biologists study how different cells develop to acquire their fate. The NYU research team, headed by Claude Desplan, a professor of biology, examined how they stay the same. Cells have complex functions that must be maintained through extensive coordination, and failure to do so could lead to “confused” cells whose function is not clear. This is particularly important for cells, such as neurons, which live for a long time — usually the entire lifetime of an animal.

The NYU researchers focused on the photoreceptor neurons in the retina of the fruit fly Drosophila. Drosophila is a powerful model for studying eye development as it is amenable to very precise genetic manipulations. This allows researchers to analyze how the visual system functions when its different elements are affected.

The work builds upon a previous finding from Desplan’s laboratory. In a 2005 study, published in Cell, Desplan and his colleagues identified a molecular pathway by which one photoreceptor cell type controls its choice to be sensitive to one color of light vs. another — in this instance, green vs. blue. This sensitivity is due to the presence of light-sensing proteins, Rhodopsins: each photoreceptor makes a decision to express either blue light-sensitive Rhodopsin5 or green light-sensitive Rhodopsin6, but not both. This exclusive expression of different Rhodopsins underlies the fly’s ability to discriminate colors.

In the Nature study, the researchers explored a phenomenon that occurs over the lifetime of an organism. Because Rhodopsins are continually produced in the eye, the researchers wanted to know what keeps each photoreceptor from starting to make the wrong Rhodopsin later in life. Their findings showed that, in fact, the Rhodopsin itself can prevent the gene encoding another Rhodopsin from turning on incorrectly.

The researchers observed that, in mutant flies that have a non-functioning Rhodopsin6 (green-sensitive) gene, the photoreceptors that would have normally produced this Rhodopsin instead slowly start to make the blue-sensitive Rhodopsin5. After two weeks, essentially all of these photoreceptors were observed making the blue Rhodopsin. The authors named one of the mutations in Rhodopsin6 gene “Frank Sinatra” because presumably it makes old eyes more sensitive to blue light — they don’t actually become blue in color.

These findings showed, then, that in normal flies, green Rhodopsin6 maintains repression of the blue Rhodopsin5 gene. This result is surprising — previously, it had not been known that Rhodopsins could control how other Rhodopsins are made.

The neurons governing our sense of smell are organized in a similar fashion. Once each olfactory neuron, which is responsible for this sense, makes a functional olfactory receptor protein, that receptor can prevent other genes encoding different olfactory receptors from being turned on in the same cell.

While the researchers did not investigate what brings about this change in Rhodopsins, they think of this as a maintenance mechanism that prevents cells from having blue and green Rhodopsins together.

“The two types of photoreceptors could be connected to different neuronal circuits in the brain which interpret the information they receive from photoreceptors as being about blue or green light,” noted Daniel Vasiliauskas, the leading author of the paper and a post-doctoral fellow at NYU. “Thus changing the Rhodopsin that a photoreceptor makes could lead to sensory confusion and reduce the fly’s ability to tell apart different colors.”

“An alternative possibility is that our findings point to a mechanism that allows a fly to adapt to changing circumstances,” he added. “If we keep flies in the dark for extended periods of time, we start seeing the same thing happening: blue Rhodopsin5 is made in the green Rhodopsin6-producing photoreceptors, leading to cells that have both. This change could be associated with changes in the downstream circuits that must now adapt to correctly interpret the information they receive.”

The research was supported by a grant from the National Institutes of Health.

Researchers Develop Optimal Algorithm for Determining Focus Error in Eyes and Cameras

0 comments

Posted on 10th October 2011 by Pacific ClearVision Institute in General |Retina

University of Texas at Austin researchers have discovered how to extract and use information in an individual image to determine how far objects are from the focus distance, a feat only accomplished by human and animal visual systems until now.

Like a camera, the human eye has an auto-focusing system, but human auto-focusing rarely makes mistakes. And unlike a camera, humans do not require trial and error to focus an object.

Johannes Burge, a postdoctoral fellow in the College of Liberal Arts’ Center for Perceptual Systems and co-author of the study, says it is significant that a statistical algorithm can now determine focus error, which indicates how much a lens needs to be refocused to make the image sharp, from a single image without trial and error.

“Our research on defocus estimation could deepen our understanding of human depth perception,” Burge says. “Our results could also improve auto-focusing in digital cameras. We used basic optical modeling and well-understood statistics to show that there is information lurking in images that cameras have yet to tap.”

The researchers’ algorithm can be applied to any blurry image to determine focus error. An estimate of focus error also makes it possible to determine how far objects are from the focus distance.

In the human eye, inevitable defects in the lens, such as astigmatism, can help the visual system (via the retina and brain) compute focus error; the defects enrich the pattern of “defocus blur,” the blur that is caused when a lens is focused at the wrong distance. Humans use defocus blur to both estimate depth and refocus their eyes. Many small animals use defocus as their primary depth cue.

“We are now one step closer to understanding how these feats are accomplished,” says Wilson Geisler, director of the Center for Perceptual Systems and coauthor of the study. “The pattern of blur introduced by focus errors, along with the statistical regularities of natural images, makes this possible.”

Burge and Geisler considered what happens to images as focus error increases: an increasing amount of detail is lost with larger errors. Then, they noted that even though the content of images varies considerably (e.g. faces, mountains, flowers), the pattern and amount of detail in images is remarkably constant. This constancy makes it possible to determine the amount of defocus and, in turn, to re-focus appropriately.

Their article was recently published in the Proceedings of the National Academy of Sciences. The research was supported by a grant from the National Institutes of Health.

The Center for Perceptual Systems is an integrated program that overlaps several separate departments: Neuroscience, Psychology, Electrical and Computer Engineering, Neurobiology, Computer Science, and Speech and Communication.

Repeated Use of Ophthalmic Antibiotics Among Patients Undergoing Intraocular Injection Therapy Linked to Antimicrobial Resistance

0 comments

Posted on 10th October 2011 by Pacific ClearVision Institute in General |Retina

Repeated exposure of the eye to ophthalmic antibiotics appears to be associated with the emergence of resistant strains of microbes among patients undergoing intraocular injection therapy for neovascular retinal disease, according to a report in the September issue of Archives of Ophthalmology, one of the JAMA/Archives journals.

According to background information in the article, more than 8 million people in the United States are affected by age-related macular degeneration, the leading cause of blindness among individuals older than 65 years in this country. Treating the neovascular or “wet” form of the disease involves monthly injections of medication into the eye; this treatment is also being studied for eye problems related to diabetes and retina vein occlusions (obstructions of veins carrying blood from the retina). To prevent the most severe complication from intraocular injection, endophthalmitis (inflammation inside the eye), ophthalmologists routinely prescribe ophthalmic antibiotics after every injection. “Repeated exposure of ocular flora [microbes living on or inside the body], however, may select for resistant bacterial strains and cultivate ‘superbugs’ with multiple-drug resistance that may considerably affect the treatment of ocular infections,” write the authors.

Stephen J. Kim, M.D., and Hassanain S. Toma, M.D., from the Vanderbilt University School of Medicine, Nashville, Tenn., conducted a randomized, controlled, longitudinal study of 48 eyes of 24 patients who, in one eye each, received intraocular injection. At baseline and after every injection, researchers obtained cultures of the conjunctiva (the membrane of the eye’s surface and the inner eyelid) for both treated and untreated (control) eyes. Patients were randomized to one of four antibiotics and after each injection used only the antibiotic they were assigned. The researchers tested the bacterial samples for susceptibility to 16 antibiotics and analyzed the bacterial DNA. Injections were administered every four weeks for at least four consecutive months, and patients were followed for one year.

Repeated exposure to fluoroquinolone antibiotics was associated with coagulase-negative staphylococci (CNS) that demonstrated significantly increased rates of resistance to both older- and newer-generation fluoroquinolones. Repeated exposure to azithromycin was associated with CNS that demonstrated significantly increased resistance to macrolides and decreased resistance to both older- and newer-generation fluoroquinolones. Specimens of CNS from treated eyes demonstrated significant increases in multiple-drug resistance; for example, 81.8 percent of CNS specimens appeared resistant to at least three antibiotics, and 67.5 percent appeared resistant to at least five antibiotics.

The researchers suggest that their results demonstrate rapid development of resistance from CNS to certain antibiotics, and that this resistance is maintained when the antibiotic is periodically readministered. “This finding has considerable implications because conjunctival flora are presumed to be the predominant source of postinjection endophthalmitis,” they write, adding that research suggests one strain of CNS is associated with greater intraocular inflammation than are strains more susceptible to antibiotics. “Our findings,” the authors conclude, “indicate the need for more judicious use of ophthalmic antibiotics after intraocular injection to reduce the potential emergence and spread of antimicrobial resistance.”

New Twist in a Blindness-Causing Disease Gene Discovered

0 comments

Posted on 10th October 2011 by Pacific ClearVision Institute in General |Retina

After more than three decades of research, University of Pennsylvania veterinarians and vision-research scientists, with associates at Cornell University, have identified a gene responsible for a blindness-inducing disease that afflicts dogs. In the process, the Penn scientists may have discovered clues about how retinal cells, and perhaps even neurons, can be regenerated.

The research was conducted by Gustavo D. Aguirre, William A. Beltran, Agnes I. Berta and Sem Genini of Penn’s School of Veterinary Medicine, along with Kathleen Boesze-Battaglia of the Penn School of Dental Medicine. They collaborated with researchers from Cornell, the National Eye Institute and the Semmelweis University of Medicine, in Hungary.

Their study was published in the open access journal PLoS ONE.

At the University of Pennsylvania in the late 1960s, Aguirre was studying rod dysplasia, a genetic disease that causes blindness in a rare breed of dog known as the Norwegian Elkhound. After the blinding disorder in the original group of dogs was eliminated, Aguirre and his colleagues endeavored to find other dogs that suffered from the same condition, only to discover a similar but separate disease instead.

This disease, which they termed early retinal degeneration, or ERD, resulted in the same blindness but in a much shorter period of time; the afflicted dogs became completely blind within a year of birth, instead of between two and four years.

Interested in gene therapies to cure blindness, Aguirre and his colleagues began narrowing down the list genes that could be responsible for ERD. As the relevant technologies improved, the researchers were able to work faster, but it was only recently that they discovered the culprit.

It was hiding in an unlikely place in the dog’s genome.

“After developing the dog genetic map in the late ’90s and then mapping the disease to a known region of the genome,” Aguirre said, “we had a physical interval to look for this gene in, but we had to prioritize gene candidates by their location and what their function is. This gene was at the bottom of our list because it’s normally only found in the brain and was not related to any known vision defect. But, lo and behold, it’s actually a very important gene to the retina.”

Identifying the gene is a first step to explaining a puzzling aspect of ERD: a “plateau” in its progression. The visual cells in the retina initially remain but then are lost and vision quickly fades. Microscopic analyses of retinas from afflicted dogs showed that, during this period, vision-related cells die at an accelerated rate but are just as quickly replaced; the cell death and compensatory formation of new ones is a new and totally unexpected finding in diseases of the retina. This work was done by A?gnes Berta, a medical doctor from Budapest who, as part of her Ph.D. studies, spent a year in the Aguirre lab through a Fulbright educational exchange program fellowship.

The researcher used an antibody-labeling system to identify how the photoreceptors were affected. The two types of these cells responsible for vision are rods, which are very sensitive to dim light, and cones, which distinguish color. Humans have short, medium and long cones, which correspond to the wavelengths of light they detect. Dogs and most other mammalian species have only two cone types, one that is sensitive to short wavelengths and another that absorbs light in both the long and medium wavelength range.

“When Berta used an antibody label for the medium and long cones, it was very discreet, but when she used label for the short wave length sensitive cones a population of rods was also labeled,” Aguirre said. “We saw that as the cell proliferates it goes back to a primordial, hybrid photoreceptor.”

Though the exact function of the relevant gene has yet to be identified, it is likely involved in the control of the cell division cycle. Normally, photoreceptors cells in the retina stop dividing shortly after birth. These hybrid photoreceptors, however, continue to divide during ERD’s plateau period.

Understanding what keeps those cells rejuvenating may hold the key for therapies that can hold off the onset of blindness, or even reverse it.

“These cells are abnormal,” Aguirre said. “Normally, there is no good evidence of large amounts of new cells being created in the retina or the central nervous system. We can better understand the way that the photoreceptor cells divide by studying this disease and potentially manipulate the gene in such a way that you could get the division component without the abnormal component. If we could regrow our diseased retinal cells, it would be wonderful.”

In addition to Aguirre, Beltran, Berta, Genini and Boesze-Battaglia, the research was conducted by Orly Goldstein and Gregory M. Acland of the College of Veterinary Medicine at Cornell University, Paul J. O’Brien of the National Eye Institute and Ágoston Szél of Semmelweis University.

The research was supported by the National Eye Institute, the National Institutes of Health, a Fulbright Educational Exchange Program Fellowship, the Foundation Fighting Blindness Center, the Van Sloun Fund for Canine Genetic Research, Hope for Vision, The ONCE International Prize for R&D in Biomedicine and New Technologies for the Blind.