Month: December 2012

Optometrists are encouraging parents and teachers across the country to take their children for a special eye test as part of its Bright Eyes For Back to School campaign which runs next week (from September 6th to 11th).

The campaign by the Association of Optometrists (AOI) includes a special eye test its members are offering for young children to help detect any sight problems early, which enables the best treatment options. Proper levels of eye care can help prevent vision problems which can affect a child throughout their life.

AOI Optometric Advisor, Lynda McGivney Nolan, said that children with undetected vision problems can lead to learning difficulties. Over 80% of what a child learns is based on vision and vision plays a vital role in playing and interacting with their peers. If a child has vision problems which are not detected and therefore untreated, that child will not be able to achieve his or her full potential. This can in turn lead to behavioural difficulties.

“Ideally all children should have their vision assessed by the age of three and then again at five, but many children in Ireland are not being seen until much later, if at all through the National School Screening system.

“Not only does this screening happen too late, it is also inadequate and can miss certain vision problems and give a high false positive rate. This results in children being referred to the community ophthalmologist for further testing, but it can take up to two years depending on where you live to get an appointment. This delay can have huge consequences for a child’s visual development.

Another point to consider is that a child is only entitled to two screenings during the whole time they are in school. A child’s eyesight can change very quickly and within a 6 month period, may go from having normal vision to developing a vision problem. This means that children of school going age should have access to regular vision assessments designed to detect

“The Association of Optometrists has developed a simple 6 point vision assessment which can be done at any local Independent Opticians Practice. It is more detailed and thorough than the screening on offer through schools and is specifically designed to identify the problems that can often be missed in young children’s eyesight,” she said.

Studies show that early access to properly designed screening systems for children is essential in providing proper levels of eyecare. If children are not seen until they are six or seven, the visual system has developed and the reversal of vision loss is far more difficult if not impossible in some cases.

The AOI said children’s eye examinations with an optometrist are not covered by the HSE and that parents must pay privately, or else risk having their child on long waiting lists to be seen at HSE clinics. The problem with these long waiting lists is that at one end, the child may be seen too late to reverse vision problems which are fully treatable, or at the very least the child has to continue struggling to cope with vision problems while trying to develop normally and keep up with his or her peers. However, the AOI believes that all school going children are entitled to a HSE covered eye examination through an optometrist as recommended by the Competition Authority report on Optometry in Ireland, in 2006.

“This would shorten waiting lists, provide more immediate access to eye care and would be far more cost effective, as the cost of an eye examination with an optometrist is significantly less than with a community ophthalmologist,” she said.

The AOI pointed out that this way, the Community Ophthalmologists can concentrate on seeing those children who need rapid access to their expertise.

Independent Optometrists participating in this campaign will have the Bright Eyes For Back to School posters on display, and as well as offering this screening will have information leaflets for parents. The screening is available to any child of school-going age.

The AOI has encouraged members to make the screening available for as nominal a price as possible. Parents are invited to contact their local participating Independent Optometrist for further details.

The AOI added that if eye problems are diagnosed parents also have the option of having the full eye examination for children carried out by an Optometrist. The Optometrist is fully qualified and can dispense spectacles and advise appropriate management without delays.

Source:
Association of Optometrists Ireland

Less than a week after Los Alamos National Laboratory’s Roadrunner supercomputer began operating at world-record petaflop/s data-processing speeds, Los Alamos researchers are already using the computer to mimic extremely complex neurological processes.

Welcome to the new frontier of research at Los Alamos: science at the petascale.

The prefix “peta” stands for a million billion, also known as a quadrillion. For the Roadrunner supercomputer, operating at petaflop/s performance means the machine can process a million billion calculations each second. In other words, Roadrunner gives scientists the ability to quickly render mountainous problems into mere molehills, or model systems that previously were unthinkably complex.

Late last week and early this week while verifying Roadrunner’s performance, Los Alamos and IBM researchers used three different computational codes to test the machine. Among those codes was one dubbed “PetaVision” by its developers and the research team using it.

PetaVision models the human visual system – mimicking more than 1 billion visual neurons and trillions of synapses. Neurons are nerve cells that process information in the brain. Neurons communicate with each other using synaptic connections, analogous to what transistors are in modern computer chips. Synapses store memories and play a vital role in learning.

Synapses set the scale for computations performed by the brain while undertaking such tasks as locomotion, hearing or vision. Because there are about a quadrillion synapses in the human brain, human cognition is a petaflop/s computational problem.

To date, computers have been unable to match human performance on such visual tasks as flawlessly detecting an oncoming automobile on the highway or distinguishing a friend from a stranger in a crowd of people. Roadrunner is now changing the game.

On Saturday, Los Alamos researchers used PetaVision to model more than a billion visual neurons surpassing the scale of 1 quadrillion computations a second (a petaflop/s). On Monday scientists used PetaVision to reach a new computing performance record of 1.144 petaflop/s. The achievement throws open the door to eventually achieving human-like cognitive performance in electronic computers. PetaVision only requires single precision arithmetic, whereas the official LINPACK code used to officially verify Roadrunner’s speed uses double precision arithmetic.

“Roadrunner ushers in a new era for science at Los Alamos National Laboratory,” said Terry Wallace, associate director for Science, Technology and Engineering at Los Alamos. “Just a week after formal introduction of the machine to the world, we are already doing computational tasks that existed only in the realm of imagination a year ago.”

Based on the results of PetaVision’s inaugural trials, Los Alamos researchers believe they can study in real time the entire human visual cortex – arguably a human being’s most important sensory apparatus.

The ability to achieve human levels of cognitive performance on a digital computer could lead to important insights and revolutionary technological applications. Such applications include “smart” cameras that can recognize danger or an autopilot system for automobiles that could take over for incapacitated drivers in complex situations such as navigating dense urban traffic.

Los Alamos National Laboratory’s computation science team working with Roadrunner includes: Craig Rasmussen, Charles Ferenbaugh, Sriram Swaminarayan, Pallab Datta, all of Los Alamos; and Cornell Wright of IBM.

The PetaVision Synthetic Cognition team responsible for the theory and codes run on Roadrunner includes: Luis Bettencourt, Garrett Kenyon, Ilya Nemenman, John George, Steven Brumby, Kevin Sanbonmatsu, and John Galbraith, all of Los Alamos; Steven Zuker of Yale University; and James DiCarlo from Massachusetts Institute of Technology.

The Roadrunner is the world’s first supercomputer to achieve sustained operating performance speeds of one petaflop/s. In partnership with Los Alamos and the National Nuclear Security Administration, Roadrunner was built by IBM and will be housed at Los Alamos National Laboratory, where it will be used to perform calculations that will vastly improve the nation’s ability to certify that the United States nuclear weapons stockpile is reliable without conducting underground nuclear tests. Roadrunner also will be used for science and engineering such as energy research, understanding dark energy and dark matter, materials properties and response, understanding complex neural and biological systems, and biomedical applications.

Roadrunner was built using commercially available hardware, including aspects of commercial game console technologies. Roadrunner has a unique hybrid design comprised of nodes containing two AMD OpteronTM dual-core processors plus four PowerXCell 8iTM processors used as computational accelerators. The accelerators are a special IBM-developed variant of the Cell processors used in the Sony PlayStation® 3. Roadrunner uses a Linux operating system. The project’s total cost is approximately $120 million.

About Los Alamos National Laboratory (lanl/)

Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and Washington Group International for the Department of Energy’s National Nuclear Security Administration.

Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.

Source: James E. Rickman

DOE/Los Alamos National Laboratory

The Insula and Evaluative Processes

Gary G. Berntson, Greg J. Norman, Antoine Bechara, Joel Bruss, Daniel Tranel, and John T. Cacioppo

The insula has been implicated in evaluative and affective processes. New findings indicate that the insula may be broadly involved in integrating affective and cognitive processes. Participants rated the positivity and negativity of picture stimuli and how emotionally arousing they found the pictures to be. Volunteers with lesions of the insula exhibited progressively reduced arousal ratings for progressively more pleasant or unpleasant pictures than did volunteers with lesions of other brain regions. Volunteers with amygdala lesions showed reduced ratings for unpleasant stimuli.

Changing Brains, Changing Perspectives: The Neurocognitive Development of Reciprocity

Wouter van den Bos, Eric van Dijk, Michiel Westenberg, Serge A.R.B. Rombouts, and Eveline A. Crone

Young adolescents tend to be selfish, mainly thinking about themselves. Luckily, most of them grow out of this and eventually start thinking more about others. How does this shift take place? Volunteers ranging in age from 12 to 22 underwent fMRI scans while participating in the Trust Game (i.e., they were given money from a hypothetical partner and decided whether to share with the partner or keep everything). The results showed that with age, adolescents were increasingly sensitive to the perspective of the other player, as indicated by sharing more money with the partner, and this was associated with increased involvement of the left temporo-parietal junction, an area involved in social perspective-taking. In contrast, young adolescents showed more activity in the anterior medial prefrontal cortex, a region associated with self-oriented thought. These findings suggest that the asynchronous development of these neural systems may underlie the shift from thinking about the self to thinking about others.

Early- and Late-Onset Blindness Both Curb Audiotactile Integration on the Parchment-Skin Illusion

Fran?�ois Champoux, Olivier Collignon, Benoit A. Bacon, Franco Lepore, Robert J. Zatorre, and Hugo Th?�oret

Presenting a single somatosensory stimulus with two successive sounds can result in perception of two distinct touch sensations. This observation is the basis of the parchment-skin illusion, in which the sound generated by hands rubbing together results in a change in how dry or moist the palms feel, depending on how the original sound is altered (e.g., change frequency). Congenitally blind individuals are better at ignoring irrelevant auditory or tactile stimuli while completing an auditory or tactile task. In the current experiment, volunteers with normal vision experienced a robust parchment-skin illusion, while the majority of early- and late-onset blind volunteers did not report changes in their perception of how dry or moist their palms were. These findings suggest that vision may play an important role in developing and maintaining the integration of auditory and touch information.

Escalating Slant: Increasing Physiological Potential Does Not Reduce Slant Overestimates

Dennis M. Shaffer and Mariagrace Flint

People are not very good at estimating the degree a hill is sloped: Research has shown that people overestimate the slant of hills by between 15 and 20 degrees. Studies have suggested that people’s perception of the slant of hills is related to how much motor effort the hills would require to climb – the more difficult the climb, the greater the overestimation of the slope. However, new findings contradict this explanation. Volunteers were asked to verbally estimate the slant of a flight of stairs and an escalator from the top or bottom. There was no difference between overestimation of the stairs’ slope and the escalators’ slope, even though stairs require more effort to climb than escalators.

Direct Electrophysiological Measurement of Attentional Templates in Visual Working Memory

Geoffrey F. Woodman and Jason T. Arita

How do we find something we are looking for? New data support the hypothesis that when we want to find something, we hold an image of it in our visual working memory. Volunteers’ brain activity was measured as they looked for an object in a complex scene. Results indicate that visual working memory mechanisms may be involved in maintaining attention for a specific target during a search task. These findings have important clinical implications – for example, working memory problems may be mistaken for attentional deficits.

Source:
Keri Chiodo

Association for Psychological Science

Innovative prism glasses can
significantly improve the vision and the daily lives of patients with
hemianopia, a condition that blinds half the visual field in both eyes. The
peripheral prism glasses, which were invented by Dr. Eli Peli, a Senior
Scientist at Schepens Eye Research Institute, were evaluated in the first
community-based multi- center trial of such a device, which is published in
the May issue of the Archives of Ophthalmology. The study was coordinated
by Dr. Alex Bowers, a Senior Scientific Associate at the Institute.

“This is the first real breakthrough in the rehabilitation of patients
with this condition,” says Peli, a world-renowned low vision expert, the
Moakley Scholar in Aging Eye Research at Schepens and a Professor of
Ophthalmology at Harvard Medical School. Peli had searched for a solution
for his hemianopia patients for many years before designing the peripheral
prism glasses, creating a prototype in his laboratory.

More than a million Americans suffer from hemianopia, which blinds the
vision in one half of the visual field in both eyes, resulting from damage
to the optic pathways in the brain. Most commonly caused by strokes, it can
also be the result of brain damage from tumors or trauma. A patient with
this condition may be unaware of what he or she cannot see and frequently
bumps into walls, trips over objects or walks into people on the side where
the visual field is missing.

Peli’s goal was to find a way to expand the visual field. He did this
by attaching small, specially designed high power prisms on the top and
bottom of one spectacle lens, leaving the center of the lens untouched. The
prisms pull in images missing from the visual field above and below the
line of sight on the side of the vision loss, and alert the patient to the
presence of a potential obstacle or hazard. The patient can then move
his/her head and eyes to examine the prism-captured image directly through
the clear center of the lens.

Prisms by their nature can shift images from one side of the visual
field to the other side (e.g., from the right side of the field to the left
side). Before Peli’s invention, others had tried to develop prism glasses
to bring the missing part of the patient’s visual field into view. However,
these previous techniques placed the prisms in the center of the glasses,
which resulted in double vision, which is disturbing and confusing. Peli’s
solution was to keep the central part prism free and place prisms above and
below.

The Archives of Ophthalmology study evaluated the glasses’ ability to
improve a patient’s walking mobility, which includes obstacle avoidance.
Forty-three patients were fitted with prism glasses in 15 community-based
clinics around the country. The clinicians interviewed them at six weeks
and after 12 months. Success was measured by how many patients continued
wearing the prism glasses and by their ranking of the prisms’ effectiveness
in assisting with obstacle avoidance while walking.

Thirty-two participants (74 percent) continued wearing the glasses at
week six. At 12 months, 20 (47 percent) were still donning the spectacles
eight hours a day and rating them as “very helpful” for obstacle avoidance.
These 12-month-plus patients were reporting significant benefits for a
variety of obstacle avoidance scenarios (e.g. walking in crowded areas,
unfamiliar places, shopping malls). According to Bowers, the first author
of the paper, “These results indicate that the glasses have great promise
for helping patients resume normal daily life.”

Peli partnered with a small optical company in Vermont-Chadwick
Optical, Inc. who funded the study in part through a National Institutes
for Health (NIH) small business grant. Peli and Karen Keeney, the President
of Chadwick Optical, created a permanent version of the prisms with higher
optical quality and better durability than the temporary prisms that were
fitted at the start of the study. These permanent prisms were provided to
15 of the study patients when they became available.

A new, higher power, version of the permanent prism glasses recently
developed by Chadwick Optical should also further expand the visual field
and be even more beneficial for patients’ mobility, according to Peli. The
prototype used in the study expanded the peripheral upper and lower visual
fields by 20 degrees without obstructing central vision. The new glasses
expand the field by 30 degrees.

A larger community-based multi-center study is currently underway to
evaluate the latest model. In addition to the higher power, the new study
is also evaluating a novel design for which Dr. Peli just received a
patient from the US patent office. Details on the new ongoing study are
available at clinicaltrials (clinical trial NCT00494676).

Schepens Eye Research Institute is an affiliate of Harvard Medical
School and the largest independent eye research institute in the nation.

Schepens Eye Research Institute
clinicaltrials

The Discovery Eye Foundation (DEF) announces their support and progress in the research of Ocular Herpres and Infectious Blindness. Their research continues to bring them closer to understanding new medical approaches, therapies and the molecular mechanisms of Ocular Herpes. Advancements have also been made in developing a new vaccine that would eventually prevent the spread of the Herpes Simplex Virus of the eye and genital tract.

Founded in 1970 by Rita and Morris Pynoos, the Discovery Eye Foundation is dedicated to finding cures and treatments for corneal and retinal eye disease. As a vital catalyst for discovery and research, they work to provide the public with up-to-the-minute and relevant information through patient outreach and patient care. DEF also supports potentially groundbreaking translational basic and applied eye research involving the retina and cornea – particularly diabetic retinopathy, macular degeneration, retinitis pigmentosa, glaucoma, diseases of the aging eye, and corneal diseases including ocular herpes, keratoconus and other degenerative conditions. DEF’s funds impact a wide variety of vision-related research programs.

Among DEF’s priority is funding a research program to combat the blinding effects of ocular herpes virus infection, which is related to the Herpes Simplex Virus of the genital tract. The research and technology being used by DEF for Ocular Herpes may be applicable to preventing genital Herpes one day. Infection with Herpes results in lifelong “latent” infection that can result in repeated recurrences. DEF’s scientists are taking several approaches toward this worldwide problem.

Drs. Steven Wechsler and Dale Carpenter, supported by DEF and the National Institute of Health (NIH), have made progress in understanding the molecular mechanisms of ocular herpes including its latency, reactivation, recurrence, and scarring. DEF supported scientists continue to gain an understanding of LAT, the major virus gene active during herpes latency, including its central molecular role in keeping the virus latent between attacks. They are looking for ways to eradicate the lifelong latent infection.

Dr. Lbachir BenMohamed, whose research is being funded by DEF and the NIH, is investigating how the herpes simplex virus escapes our natural immune system, which is another way the virus remains a lifelong concern. Understanding and harnessing this immune process could lead to therapies to eradicate this chronic infection.

Drs. Anthony Nesburn, who is the Medical Director of DEF, and BenMohamed are currently developing a novel vaccine that would provide an effective and less costly means of preventing and treating ocular herpes. The underlying rationale for these grants is to understand and eventually eradicate debilitating Herpes Simplex Virus of the eye and genital tract. Their findings are currently being evaluated in pre-clinical studies.

Drs. Wechsler and James Jester have developed a powerful new approach to understanding how herpes infection causes corneal scarring through funding provided by DEF and the NIH. This approach may well lead to new ways to save the vision of those with ocular herpes-a major cause of corneal blindness worldwide.

The Discover Eye Foundation

Babies with an eye-alignment disorder called infantile esotropia have delays in motor development milestones, but development “catches up” after corrective surgery, reports a study in the April Journal of AAPOS (American Association for Pediatric Ophthalmology and Strabismus).

Led by James R. Drover, PhD, of the Retina Foundation of Southwest Texas, Dallas, the researchers assessed developmental milestones in 161 infants with infantile esotropia, or crossed eyes. These infants need surgery on the eye muscles to correct the alignment. However, it has been unclear whether surgery to correct esotropia influences other aspects of infant development.

To answer this question, the researchers had parents complete an infant development questionnaire before and/or after corrective surgery. The questionnaire assessed fine-motor skills, such as grasping a toy and handling a bottle (sensorimotor development); as well are large-muscle skills, such as sitting, standing, and walking (gross motor development). A group of children with normal eye alignment were studied for comparison.

Before surgery, infants with esotropia had delays in both milestones. The developmental delays appeared as early as four to five months of age and were still present at ten months.

The sensorimotor delays were “particularly profound,” and probably reflected the importance of normal binocular vision (both eyes working together) in fine-muscle tasks. The delays in gross motor development, while not as severe, were still significant.

In contrast, infants tested after esotropia surgery had no delays in developmental milestones. In fact, they actually had a faster rate of sensorimotor development, suggesting that correcting their binocular vision helped their development to “catch up” to that of normal infants.

Infantile esotropia is one of a group of disorders called strabismus, in which the eyes are not aligned normally. Without surgery to correct the problem, depth perception cannot develop. Because vision develops rapidly between three to eight months of age, infantile esotropia might cause delays in developmental milestones – for example, grasping objects, crawling, or walking – that depend on normal vision. However, previous studies were unclear as to whether early surgery helps normal development, partly because many babies with esotropia are not sent for expert evaluation by a pediatric ophthalmologist until they are over one year old.

The new results show that babies with infantile esotropia have significant delays in developmental milestones before surgery, and, suggests that development catches up to normal after surgery to correct eye alignment. Dr. Drover and colleagues suspect that the rapid rate of development after surgery results from the improvement in binocular function.

“Doctors continue to disagree over when is the best time to correct strabismus in children, because most of the focus has been on when it can best help their vision,” comments Dr. David G. Hunter of Children’s Hospital Boston and editor-in-chief of the Journal of AAPOS. “This study says that surgery to correct strabismus doesn’t just help the eyes – it helps the whole child.”

The article appears in Journal of AAPOS (April 2008), published by Elsevier on behalf of the American Association for Pediatric Ophthalmology and Strabismus.

About Journal of AAPOS

Journal of AAPOS presents expert information on children’s eye diseases and on strabismus as it impacts all age groups. Major articles by leading experts in the field cover clinical and investigative studies, treatments, case reports, surgical techniques, descriptions of instrumentation, current concept reviews, and new diagnostic techniques. The Journal is the official publication of the American Association for Pediatric Ophthalmology and Strabismus.

About Elsevier

Elsevier is a world-leading publisher of scientific, technical and medical information products and services. Working in partnership with the global science and health
communities, Elsevier’s 7,000 employees in over 70 offices worldwide publish more than 2,000 journals and 1,900 new books per year, in addition to offering a suite of
innovative electronic products, such as ScienceDirect (sciencedirect/), MD Consult
(mdconsult/), Scopus (info.scopus/), bibliographic databases, and online reference works.

Elsevier (elsevier/) is a global business headquartered in Amsterdam, The Netherlands
and has offices worldwide. Elsevier is part of Reed Elsevier Group plc (reedelsevier/), a world-leading publisher and information provider. Operating in the science and medical, legal, education and
business-to-business sectors, Reed Elsevier provides high-quality and flexible information solutions to users, with increasing emphasis on the Internet as a means of
delivery. Reed Elsevier’s ticker symbols are REN (Euronext Amsterdam), REL (London Stock Exchange), RUK and ENL (New York Stock Exchange).

Source: Jayne Dawkins

Elsevier

Subjects like physics, calculus and biology are challenging for most students, but imagine tackling these topics without being able to see the graphs and figures used to teach them. A new smartpen and paper technology that works with touch and records classroom audio aims to bring these subjects to life for blind students.

“Mainstream approaches to teaching STEM (science, technology, engineering and math) courses all rely strongly on diagrams, graphs, charts and other figures, putting students with visual disabilities at a significant disadvantage,” Andy Van Schaack, lecturer in Vanderbilt University’s Peabody College of education and human development, said. “Our goal is to enable students and teachers to produce and explore diagrams and figures through touch and sound using a smartpen and paper technology that is low-cost, portable and easy to use.”

Van Schaack and colleague Joshua Miele, a researcher at the Smith-Kettlewell Eye Research Institute who is blind, have received a $300,000 grant from the National Science Foundation to apply the new technology, created by technology company Livescribe, to this effort. Van Schaack is Livescribe’s senior science adviser.

“My area of expertise is instructional technology. I spend a lot of my time trying to figure out how to use technology to make teaching and learning more effective, efficient and accessible,” Van Schaack said. “A new world of possibilities has opened for the rapid creation of portable, low-cost, high-quality accessible graphics enhanced with audio. For example, a visually impaired psychology student could learn neuroanatomy by exploring a diagram of the brain, with each lobe, gyrus and sulcus’s name spoken as the smartpen touches it.”

The Livescribe smartpen recognizes handwritten marks through a camera inside its tip that focuses on a minute pattern of dots printed on paper. It captures over 100 hours of audio through a built-in microphone and plays audio back through a built-in speaker or 3D recording headset. Files are uploaded from the pen to a computer using a USB connection. The technology will be much more affordable and portable than previous products used for this purpose – students can just put it in their backpacks with the rest of their books and notebooks.

Van Schaack and Miele will be using a prototype of the Livescribe smartpen and a Sewell Raised Line Drawing Kit, a Mylar-like film that is deformed when a student writes on it with a pen, creating raised drawings. Students will be able to touch a hand-drawn figure with their smartpen to hear audio explanations of its features.

As for other uses of the smartpen, Van Schaack believes the possibilities are endless.

“It really is a new computer platform – it includes most of the technology found in a typical laptop, but gets its information from handwriting rather than from a keyboard and mouse,” Van Schaack said. “One of the most immediate uses of it that I see will be for college students. It will allow them to spend more time listening in class while taking more of an outline form of notes. Later, when they are reviewing their handwritten notes, they can tap within them to hear what the professor was saying when they wrote a particular note, giving them the opportunity to annotate them for accuracy and additional detail.”

The smartpen is expected to hit stores during the first quarter of 2008 at a cost of less than $200. Livescribe interactive notebooks will run about the same price as a good quality notebook from a college bookstore.

For more information about the smartpen, visit livescribe/.

For video of Van Schaack and the smartpen, visit vanderbilt.edu/news/smartpen.

Source: Melanie Moran

Vanderbilt University

Presently keratoconus is treated through eyeglasses, hard contact lenses, and a newer treatment, INTACS plastic rings inserted into the mid layer of the cornea to flatten it, changing the shape and location of the cone. In 15-20% of the cases, cornea transplant surgery is necessary. The Cornea Research Foundation of America is one of 9 sites in the U.S. currently participating in a new clinical research investigation to study the benefits of corneal collagen cross-linking (CXL) in subjects with progressive keratoconus and corneal ectasia after prior refractive surgery. These studies are the first in the U.S. of CXL designed to assess the safety and effectiveness of CXL for slowing the progression of both of these conditions.

“Because the FDA usually requires data from two separate studies before approving a new drug or device, we are conducting two cross-linking studies: one is for the treatment of keratoconus and the other is for treatment of post-refractive ectasia, a rare complication of refractive surgery,” says Marianne Price, executive director of the Cornea Research Foundation of America.

The FDA permitted study is sponsored by Swiss-based Peschke Meditrade GmbH. Corneal collagen cross-linking is a procedure that involves administering riboflavin and UVA in carefully selected parameters that strengthen the front layers of the cornea and avoid damage to the back of the eye. The riboflavin and UVA light source that is used for CXL are both investigational in the United States and are not yet approved by the FDA.

The Foundation started the collagen cross-linking study in January 2008. The FDA has given permission for enrollment of 160 patients into each study. People interested in more information about the study or participating in the study can contact the Cornea Research Foundation of America. Subjects may be eligible for the study if they have the following in one or both eyes, or are:

— 18 years of age or older

— Have been diagnosed with progressive keratoconus or have had previous vision correction surgery and now have corneal ectasia

— Vision with contact lenses or glasses is worse than 20/20

— Corneal thickness greater than 300 microns at the thinnest point

— If you are female, you cannot be pregnant

— Can leave contact lenses out for at least 3 months in the eye to be treated

— If you have keratoconus, you cannot have had previous corneal surgery or Intacs

— If you have keratoconus, it must have gotten worse in the last two years based on your previous eye exams. You will need to contact your eye doctor or allow us to contact your eye doctor to get your eye exam records for your vision measurements, corneal maps (topography) and contact lens or glasses prescriptions.

Expert Source: Dr. Marianne Price, executive director of the Cornea Research Foundation of America. Dr. Price is a sought after speaker and published author, a member of the American Academy of Ophthalmology, the Association for Research in Vision and Ophthalmology, the American Society of Cataract & Refractive Surgery, and Ophthalmic Women Leaders. Dr. Price holds a bachelor’s degree in engineering science from the University of Notre Dame and both an MBA in finance and a doctorate in medical and molecular genetics from Indiana University.

Cornea Research Foundation of America
9002 N Meridian St., Ste. 212
Indianapolis
IN 46260
United States
cornea

Onchocerciasis is an infection caused by Onchocerca volvulus, a parasite nematode worm transmitted to humans by a species of black fly of the Simulium genus whose larvae develop in fast-flowing rivers. Infected subjects suffer not only from severe skin lesions but also eye damage that can lead to irreversible loss of sight, hence the name ‘river blindness’. A huge majority — 99% — of the 37 million people infected by the parasite live in SubSaharan Africa. Ivermectin, a medicine capable of killing the parasite embryos (the microfilariae) circulating in the organism of patients and temporarily interrupting the nematode’s reproduction, is the only treatment used for onchocerciasis control. Since 1995, the African Programme for Onchocerciasis Control (APOC) has been covering 19 of the continent’s 28 countries hit by the disease. Access to this treatment is possible for 70 million people and has significantly diminished the onchocerciasis-induced morbidity. However, the doubling of cases of infection in certain communities of Ghana between 2000 and 2005, in spite of annual treatments, created fear of the emergence of ivermectin-resistant strains. Such apprehension appears particularly justified in that a high degree of therapeutic cover is achieved during mass distribution campaigns and hence only a tiny part of the parasite population targeted remains unexposed to drug treatment pressure.

Since 1994, a team of IRD researchers, working jointly with Cameroon researchers and others from McGill University of Montreal, has been monitoring a cohort of Cameroon patients benefiting from repeated treatments with ivermectin. Regular parasite sampling from these subjects was performed over a 13-year period in order to determine the changes in the genetic structure of Onchocerca volvulus populations. Each occasion involved measurement of the genotype frequency of heterozygotes and homozygotes for the gene coding ??-tubulin, a protein involved in the organization of the parasite’s cells. The team focused on this particular gene because it acts as a marker of resistance to ivermectin in other nematode species parasitic on cattle. As a control, they monitored the changes in genotype frequency of two other genes, known for their high evolutionary stability over time. The proportion of homozygotes and heterozygotes for these two genes remained stable throughout the investigation, but the situation was completely different for the ??-tubulin gene. Between 1994 and 1998, the percentage of parasites showing a genotype homozygous for this gene fell from 79 to 31% in subjects receiving quarterly treatment with ivermectin. At the same time, the proportion of heterozygous genotypes changed in the opposite sense, rising from 21 to 69%. These results could be the sign of adaptation of nematode worm populations to repeated treatments using this drug. The research team inferred that the parasites showing a genotype homozygous for ??-tubulin are more susceptible to it. As courses of treatment progressed, they would therefore gradually disappear, to the benefit of the more resistant heterozygous strains. Ivermectin’s effect on microfilariae, other than its direct one, is to prevent them from leaving the uterus of adult worms, for several months after treatment: this is its embryostatic effect. Post-treatment, there were more microfilariae in the uterus of homozygous female parasites than in those of heterozygous females. This could mean that, in the latter, the microfilariae succeed in leaving the uterus, as they usually do in the absence of treatment, and therefore that the embryostatic effect of ivermectin would be diminished. Contrary to the effect anticipated, the repeated exposure to treatments could in this way select those worms more able to keep up the production of new generations. Nevertheless, the drug’s direct action on the microfilariae appeared not to change, and hence, for the moment, there is no reason to call into question the current control strategy against the disease based on annual treatments with ivermectin.

Affirmation of the results requires further investigations1, starting from new cohorts subjects infected by Onchocerca volvulus who have not yet been treated with ivermectin. This type of approach should bring more information on the risks of the parasite’s resistance to this drug. If such risks were confirmed, then the whole onchocerciasis control strategy would probably have to be revised. Nevertheless, for many years to come, ivermectin could well remain the sole drug applicable for mass treatment in measures to control river blindness.

Gr?�gory Fl?�chet – DIC

1. A study coordinated by the IRD and financed by the French Agence nationale de la recherche (ANR), aiming to find more extensive information on possible resistance of the onchocerciasis parasite to ivermectin, is currently being conducted in Cameroon jointly with a team from INRA, research scientists from the universities of Yaound?� I and Buea (Cameroon), the Cameroon Ministry of Public Health, McGill University of Montreal (Canada) and Imperial College London (United Kingdom).

Source: Gregory Flechet

Institut de Recherche Pour le D?�veloppement

Like many diseases, causes for age-related macular degeneration (AMD) can be categorized as either “nature” or “nurture”. Researchers think these factors, when used in the proper model, can be strong predictors of the disease.

AMD is the leading cause of vision loss in Americans 60 years of age and older.

A study published in the Association for Research in Vision and Ophthalmology’s peer-reviewed Investigative Ophthalmolgy & Visual Science (“Prediction Model for Prevalence and Incidence of Advanced Age-Related Macular Degeneration Based on Genetic, Demographic and Environmental Variables”) shows that multiple genetic, ocular and environmental factors, including six genetic variants, age, smoking and body mass index heavily contribute to the incidence of AMD. Because all of these factors are related to AMD, they were combined and used to develop a predictive and possibly diagnostic model.

“The determinants of the model can be assessed by completing a questionnaire and taking a blood test, and it is a tool which could be used to help guide prevention and treatments” said lead author and principal investigator, Johanna M. Seddon, MD, ScM, Professor of Ophthalmology at Tufts University School of Medicine and Director of the Ophthalmic Epidemiology and Genetics Service at Tufts Medical Center. “Such information may be also be useful for screening those at high risk of AMD due to a positive family history or having signs of early or intermediate disease even among those with normal vision,” the study says.

Over 1,400 individuals in the Age-Related Eye Disease Study (AREDS) with an average follow-up time of 6.3 years were evaluated, and genetic specimens were genotyped in the collaborator’s lab in Boston. Both prevalence and development of advanced dry and wet AMD over the course of the study were included in the analyses. Researchers found all tested variables to be independently associated with AMD. The predictive power of the variables in the formula was very high, and the probability that the risk score based on the group of factors in that model for a progressor was higher than the corresponding risk score for a random non-progressor within the same 10 year age group was 83%.

Their research also shows that although AMD has a strong genetic component, healthy behaviors can modify your genetic susceptibility. For example, among individuals with one genotype, the homozygous C3 risk genotype, the likelihood of progression to the advanced form of AMD increased from about three-fold for nonsmokers to nearly 10-fold for smokers.

“Our algorithm could help with the selection of study participants for treatment trials and could one day enable doctors to choose the most efficacious treatment for individual patients,” Dr. Seddon said. “It also gives any older person concerned about AMD, or any patient with early stages or a family history of AMD, even more incentive to avoid risk factors such as smoking and excessive weight.”

Investigative Ophthalmology & Visual Science is a peer-reviewed publication of the Association for Research in Vision and Ophthalmology (ARVO).

ARVO is the largest eye and vision research organization in the world. Members include more than 12,000 eye and vision researchers from 73 countries. The Association encourages and assists research, training, publication and dissemination of knowledge in vision and ophthalmology.

Source: Association for Research in Vision and Ophthalmology