Month: July 2014

This month’s Ophthalmology, the journal of the American Academy of Ophthalmology, includes new studies on links between eye diseases and two widely-prescribed drugs: SSRI (selective serotonin reuptake inhibitor) antidepressants, and amantadine, a Parkinson’s disease treatment.

Some Antidepressants May Bump Up Cataract Risk

Seniors who take SSRI antidepressants may be more likely to develop cataracts, says the first major study to examine this interaction. The risk appears to increase by about 15 percent, which in the United States would translate to 22,000 cataract cases attributable to antidepressant use. The study, led by Mahyar Etminan, PharmD, of Vancouver Coastal Health Research Institute, Canada, assessed data for nearly 19,000 people age 65 or older, all of whom also had cardiovascular disease. Their records were compared to about 190,000 controls.

The effect was strongest for three SSRIs: Luvox (fluvoxamine) increased risk by 39 percent, Effexor (venlafaxine) by 33 percent and Paxil (paroxetine) by 23 percent. The apparent increased risk was associated only with current, not past, drug use. Some antidepressants did not appear to be associated with cataract risk, but this could have been because the numbers of study participants using these drug types were too small to show effects, or because only specific agents in certain medications are related to cataract formation. These questions need further study.

“The eye’s lens has serotonin receptors, and animal studies have shown that excess serotonin can make the lens opaque and lead to cataract formation,” Dr. Etminan said. “If our findings are confirmed in future studies, doctors and patients should consider cataract risk when prescribing some SSRIs for seniors,” he added.

Earlier research linked beta blocker medications and oral and inhaled steroids to higher cataract risk, and a recent Swedish study suggests that women’s hormone replacement therapy may also raise risk.

Long-term Use of Parkinson’s Drug May Impact Vision

Parkinson’s disease, the second most common neurodegenerative disease after Alzheimer’s, is often treated with amantadine. The drug helps alleviate patients’ motor problems and may be taken for years. Doctors have long known that amantadine treatment causes abnormal changes in the cornea in some Parkinson’s patients. The cornea is the eye’s clear outer surface that provides most of the visual power. Usually corneal reactions occur soon after starting the drug and disappear a few weeks after it is withdrawn. But sometimes corneal disorders appear only after years of treatment, and the corneas of these patients often do not recover when amantadine is stopped. Won Ryang Wee, MD, PhD, and his colleagues at Seoul National University College of Medicine, South Korea, studied whether the effect of amandatine on corneal endothelial cells is dependent on the cumulative dose received.

The researchers compared 169 eyes of amandatine-treated patients with an equal number of matched controls; the average age of all subjects was 59. They found that the patient group with the highest cumulative amandatine intake and/or longest duration of treatment (up to 8 years) had the most significant reductions in endothelial cell density (ECD). Endothelial cells work to keep excess water out of the main body of the cornea. When there are too few endothelial cells, corneal edema (swelling) results and vision is impaired. This study noted two early indicators of abnormal corneal changes in response to amandatine, before ECD reduction occurred: deformation of the normal hexagonal cell shape, and increase in cell size variation. The findings also show that ECD reduction in response to amandatine treatment does not occur quickly.

“Assuming other studies confirm these results, ophthalmologists and neurologists should consider evaluating a patient’s corneal endothelium at the beginning of treatment with amandatine and reassess at regular intervals if the drug is used long term,” Dr. Wee said, “and additional monitoring would be needed for patients with other conditions that reduce ECD – such as recent cataract surgery or ongoing glaucoma, uveitis or Fuch’s dystrophy – because corneal edema could develop during treatment.”

Source:
Mary Wade
American Academy of Ophthalmology

View drug information on Effexor; LUVOX; Paxil CR.

A team of scientists from Singapore has discovered two genes from the collagen family which demonstrate strong association with Central Corneal Thickness (CCT). CCT is a risk factor of glaucoma, the most common cause of irreversible blindness worldwide.

The identification of genetic determinants affecting CCT in the population is crucial in helping to provide useful insights into the mechanisms underlying the association between CCT and glaucoma. This will definitely increase knowledge on the pathogenesis of glaucoma.

The study, the largest genome-wide association study (GWAS) ever on CCT and the first in Asia, was jointly conducted by scientists from the Genome Institute of Singapore (GIS), an institute of Singapore’s Agency of Science, Technology and Research (A*STAR), the Singapore Eye Research Institute (SERI), the National University of Singapore (NUS), the Duke-NUS Graduate Medical School, as well as colleagues from the USA and Australia.

Their research, published in Human Molecular Genetics, is the first ever genome-wide study of CCT conducted on Singaporeans on such a massive scale. More than 5,000 individuals were drawn from two ethnic populations in Singapore via the SERI-led landmark, community-based studies that systematically documented the frequency,
causes and impact of low vision and major eye diseases in the different racial/ethnic groups in Singapore.

The two ethnic populations were the Malays and Indians, drawn from the Singapore Malay Eye Study (SiMES), which successfully looked at 3,280 of Singapore’s Malay population from 2004 to 2006, and the Singapore Indian Eye Study (SINDI) that examined 3,400 Singapore Indians between 2007 and 2009.

“GWAS have been conducted primarily in European populations, and an interest in the Asian populations is only just beginning to emerge. The Singapore population has, until now, been untouched by GWAS efforts. This is our first attempt at assembling a large sample from the Singaporean cohort”, said GIS Research Fellow and one of the first authors of the paper, Dr Khor Chiea Chuen. “This study shows that there is good reason to continue genetic studies on Singaporeans as some of the genes governing traits in Singapore Malays and Indians are very different when compared to that of Europeans.”

He added, “To realize our aim at personalized medicine using human genetic profile as a guide, we have to conduct this kind of large-scale genetic studies in our own Singapore population to find the answers, as many European results cannot be generalized to Asians, let alone Singaporeans from different ethnic groups.”

Associate Professor Aung Tin, Deputy Director, SERI and Head Glaucoma Service, SNEC, added, “Glaucoma is a major cause of blindness and central corneal thickness is a key risk factor for the disease. By finding genes related to central corneal thickness in our population, we are close to identifying genes for glaucoma and may one day be able to predict who is at risk of this major eye disease in Singapore.”

On a similar note, Professor Adrian Hill, Director of The Jenner Institute in the UK, also commented, “This is an impressive large-scale study of one of the most important causes of blindness. The Singapore team provides strong evidence for the involvement of collagen-related genes in this disorder, opening new avenues for the understanding and better treatment of this condition.”

“This was a very successful partnership between clinical research scientists with expertise in eye-related genetics at SERI and statistical geneticists with expertise in
whole genome analysis at GIS” said Dr Eranga N. Vithana, Head of Ocular Genomics, Assistant Director, Basic and Experimental Sciences at the SERI.

Dr Eranga further commented, “We hope to have many such research collaborations in the future with equally successful outcomes.”

Notes

Research publication:

The research findings described in the press release can be found in the 3 December, 2010 advance online issue of Human Molecular Genetics under the title “Collagen related genes influence glaucoma risk factor, central corneal thickness”.

Authors:

Eranga N Vithana,1,2???* Tin Aung1,2, 3??? Chiea Chuen Khor,4,5??? Belinda K Cornes,1 Wan-Ting Tay,1 Xueling Sim,5 Raghavan Lavanya,1 Renyi Wu,1 Yingfeng Zheng,1 Martin L Hibberd,4 Kee Seng Chia,5,6 Mark Seielstad,7 Liang Kee Goh,8 Seang-Mei Saw,1,2,5,6 E Shyong Tai,5,6,9??� Tien Y Wong 1,2,6,10??�

1. Singapore Eye Research Institute, Singapore National Eye Centre, Singapore;

2. Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore;

3. Singapore National Eye Centre, Singapore;

4. Infectious Diseases, Genome Institute of Singapore, A*STAR, Singapore;

5. NUS-GIS Center for Molecular Epidemiology, Singapore.

6. Department of Epidemiology and Public Health, Yong Loo Lin School of Medicine, National University of Singapore, Singapore;

7. Institute for Human Genetics & Department of Laboratory Medicine, University of California San Francisco

8. Duke-NUS Graduate Medical School, Singapore

9. Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore;

10. Centre for Eye Research Australia, University of Melbourne, Victoria, Australia.

??? These authors contributed equally and are joint first authors

??� These authors are joint last authors

Source:

Genome Institute of Singapore

Eyes are among the earliest recognisable structures in an embryo; they start off as bulges on the sides of tube-shaped tissue that will eventually become the brain. Researchers from the European Molecular Biology Laboratory (EMBL) in Heidelberg have now discovered that cells are programmed to make eyes early in development and individually migrate to the right place to do so. The study, published in this week’s issue of the journal Science, overturns the textbook model of the process and suggests that also other organs might be formed by the movement of single cells rather than sheets of entire tissues.

Jochen Wittbrodt and his lab at EMBL made the discovery using advanced microscope techniques to track individual cells in the transparent embryos of a small fish called Medaka.

“You can think of the tube as a deflated balloon shaped like a Mickey Mouse,” Wittbrodt says. “As the fish grows, the eyes gradually bulge out from the tube, the way Mickey Mouse ears expand as a balloon is filled with air. Most scientists have thought that cells in the neighbouring regions grow to make the bulges. What we’ve seen is that individual cells migrate to this area from the central region of the tube – as if to make ears, tiny rubber particles had to fly out from the air inside the balloon.”

In 2001, Felix Loosli from Wittbrodt’s laboratory discovered a protein called Rx3 that is required for eye formation. Only cells that will become the eye begin producing this molecule early on in development. Martina Rembold, also from Wittbrodt’s group, labeled these cells with a fluorescent marker and tracked them using advanced software developed by Richard Adams at the University of Cambridge. Following the cells required recognizing them under the microscope and assembling tens of thousands of images into 3D movies.

“Rx3 plays a crucial role in giving the cells their identity and telling them where to go,” says Rembold. “Normally, single cells migrate actively and one-by-one from the centre of the brain to form eyes. But in strains of fish that have no Rx3, no eyes develop and the cells remain inside the brain, because nothing tells them to migrate to the right place.”

In the embryo the paths for cell movements are signposted by cues that by attracting or repelling different types of cells guide them into the right direction. Thanks to Rx3 eye cells prefer the cues guiding the way to the eye field. Following them the cells migrate individually against the stream of brain cells that are repelled by the same signal. Without Rx3 eye cells lose their preference and follow the bulk of brain cells into the other direction.

Many other organs are thought to form when sheets of nearby cells expand to form new shapes. The current study suggests that individual cell migration might be a more common phenomenon than scientists have suspected.

“We know that cell migration is important in the formation of many other organs, such as the heart,” Wittbrodt says. “We’d like to understand how tissues originate and how cells move in the early embryo and to decipher the cues that tell them where to go. This approach of tracking individual cells will help us to understand these processes better.”

Contact: Yvonne Kaul

European Molecular Biology Laboratory

A recent survey by the American Optometric Association (AOA), revealed that Americans aren’t taking their eye health as seriously as they should, particularly when it comes to protecting their eyes from the potentially blinding effects of diabetes and diabetic eye disease.

According to the AOA’s 2007 American Eye-Q® survey, more than 60 percent of adults know that diabetes is detectable through a comprehensive eye exam. However, only 32 percent of adults who do not wear glasses or contacts, have seen a doctor of optometry in the past two years. The annual American Eye-Q® survey identifies attitudes and behaviors of Americans regarding eye care and related issues.

With nearly two-thirds of adults not receiving regular, comprehensive eye exams, millions of Americans are not only putting their vision, but also their health, at risk. In fact, diabetes is a top cause of new cases of blindness among adults.

“More than 21 million Americans have diabetes, and perhaps of even greater concern, more than 6 million Americans are unaware that they have the disease,” said Dr. Jorge Cuadros, AOA’s Diabetes Eye Care Expert and University of California School of Optometry professor. “In addition to overall health complications, diabetes can cause vision changes and ultimately lead to blindness.”

Optometrists can serve as the first line of detection for diabetes, since the eye is the only place on the body that blood vessels can be seen without having to look through the skin. All individuals with known diabetes need to have dilated eye exams each year; despite the fact that only four out of ten Americans recognize that diabetic patients should have their vision checked annually, according to the 2007 American Eye-Q®.

“It is especially important for individuals who are at high risk for diabetes to visit an eye doctor regularly for dilated eye exams,” said Dr. Cuadros.

According to the American Diabetes Association, an estimated 54 million Americans aged 40 to 74 (40.1 percent of the U.S. population in this age group) have pre-diabetes, a condition that puts them at high risk for developing type 2 diabetes.

Early detection is critical in maintaining healthy vision. Additionally, several factors influence whether someone with diabetes develops diabetic retinopathy. These include controlling blood sugar control and blood pressure levels, the length of time with diabetes, race and family history.

Be sure to see an optometrist if your vision becomes blurry; you have trouble reading signs or books; experience double vision; feel pressure in your eyes; encounter straight lines appearing indistinct; or your side vision is limited.

To find an optometrist in your area, or for additional information on eye health, specifically diabetic retinopathy, please visit aoa.

About the American Optometric Association (AOA)

The American Optometric Association represents more than 34,000 doctors of optometry, optometry students and paraoptometric assistants and technicians. Optometrists serve patients in nearly 6,500 communities across the country, and in 3,500 of those communities are the only eye doctors.

American Optometric Association doctors of optometry are highly qualified, trained doctors on the frontline of eye and vision care who examine, diagnose, treat and manage diseases and disorders of the eye. In addition to providing eye and vision care, optometrists play a major role in a patient’s overall health and well-being by detecting systemic diseases such as diabetes and hypertension. Doctors of optometry have the skills and training to provide more than two-thirds of all primary eye care in the United States.

Prior to optometry school, optometrists undergo three to four years of undergraduate study that typically culminates in a Bachelor of Science degree in a field such as biology or chemistry.

Optometry school consists of four years of post-graduate, doctoral study concentrating on both the eye and systemic health. In addition to their formal training, doctors of optometry must undergo annual continuing education to stay current on the latest standards of care. For more information, visit aoa.

Researchers at the Keck School of Medicine of the University of Southern California (USC) have developed a potential therapy for blindness that involves delivering a gene encoding a light-sensitive protein to inner retinal cells, enabling photosensitivity in these cells and restoring visual function in mouse models.

The research, led by senior author Alan Horsager, Ph.D., a neuroscientist at the Keck School, focuses on blindness caused by retinitis pigmentosa and age-related macular degeneration, conditions that lead to gradual loss of photoreceptors in the retina and eventual blindness. Horsager’s research targets other cells in the retina called bipolar cells, which are part of the retina’s intricate signal processing system. The proof of concept paper was published on April 19 in the journal Molecular Therapy.

“It’s a very targeted approach that maintains the natural processing of the retina,” said Horsager. “There is a lot more to understand, but initial indications suggest we have developed something that can have enormous benefit to people. Preclinical studies are the next step to determine the potential therapeutic benefit for humans.”

After the gene encoding the light-sensitive protein is delivered via an adeno-associated virus, the bipolar cells become light sensitive and take over the light-capturing function of the lost photoreceptors.

This effort builds on the research of Ed Boyden, Ph.D., assistant professor at the Massachusetts Institute of Technology (MIT). Horsager and Boyden, together with Ben Matteo, have co-founded Eos Neuroscience, Inc. to help translate this technology into the clinic. Dr. Horsager serves as the chief science officer for Eos Neuroscience, Inc., and has an equity interest in the company.

“This is a massive collaborative effort between USC, MIT, the University of Florida, and Eos Neuroscience, building on a lot of great science,” said Horsager. “We are simply aggregating this science and establishing proof-of-concept for a blindness therapy.”

The research establishes that this therapy works independent of the underlying cause of photoreceptor degeneration, suggesting that people suffering from retinitis pigmentosa or age-related macular degeneration would benefit.

“We conducted multiple studies to establish that this technology is safe and does not appear to generate any immune response or inflammation in the eye,” said Mehdi Doroudchi, Ph.D., the first author and head of cell biology at Eos. The delivery system, an adeno-associated virus, is currently being used in multiple clinical trials of gene therapy throughout the U.S. and abroad.

The technology used to make the bipolar cells light-sensitive, known as optogenetics, had its origins in a collaboration spearheaded by Boyden in 2004, which revealed that a light activated protein from algae known as channelrhodopsin-2, when expressed in neurons, made them activatable by light. Boyden’s group has since revealed an entire family of light-sensitive proteins that enable neurons to be switched on and off by different colors of light, which are now in widespread use throughout the field of neuroscience for analyzing how neurons work in brain circuits.

“It’s really exciting to think of the clinical applications opened up by the ability to control neurons by light,” said Boyden. “The eye, which can access light from the outside world, is a perfect test bed for the use of optogenetic tools for treating intractable disorders.”

Source:

University of Southern California

The future of clinical ophthalmology may be endangered by the decline in the number of human donor eyes provided by U.S. eye banks according to an article published in the July 2006 issue of Investigative Ophthalmology & Visual Science (IOVS).

According to a survey of U.S. members of the Association for Research in Vision and Ophthalmology (ARVO), the major prohibitory factor in the use of human eye tissue is lack of availability of tissue meeting stringent criteria. The survey’s conductor, Christine A. Curcio, PhD, of ARVO’s Research Tissue Acquisition Working Group (RTAWG), found that only cost exceeded this factor among those surveyed. Respondents also indicated that local eye banks are the most common tissue source although most investigators use multiple tissues sources, including remote eye banks to acquire adequate human eye tissue needed for research.

The availability of human eye tissue for research has been severely impacted by federal regulations and state laws enacted over the last decade, and some individual eye bank practices may be of importance on a local level (e.g., laws prohibiting medical examiners from releasing eye tissue in cases of violent or suspicious death).

The RTAWG believes that the decline in human research tissue may be managed in the short term by researchers working closely with eye banks and other providers, communicating on a regular basis, and clarifying their experimental needs and expectations.

“No where do impediments to obtaining human eyes for research have more impact than in the effort to understand age-related macular degeneration, the leading cause of new vision loss in the elderly,” said Curcio, a professor of ophthalmology at the University of Alabama at Birmingham. “Macular degeneration, an advanced form of which now has treatment options, still lacks a laboratory animal model that displays the full range of pathology typifying the human disorder. Thus, human tissues are particularly critical.”

IOVS is published by the Association for Research in Vision and Ophthalmology (ARVO). For more information, logon to iovs/

ARVO is a membership organization of more than 11,500 eye and vision researchers from over 70 countries. Established in 1928, the Association encourages and assists its members and others in research, training, publication and dissemination of knowledge in vision and ophthalmology. ARVO’s headquarters are located in Rockville, Md. For more information about ARVO, logon to arvo/.

Contact: Elinore Tibbetts

Association for Research in Vision and Ophthalmology

It is estimated that more than 1 billion individuals worldwide in 2005 had presbyopia, or age-related difficulty in seeing objects nearby, with an estimated 410 million with the condition unable to perform tasks requiring near vision, according to a report in the December issue of Archives of Ophthalmology, one of the JAMA/Archives journals.

Presbyopia occurs with age, as the eye’s lens loses its elasticity and ability to focus on close objects, according to background information in the article. “Although known physiology and population demographics suggest that presbyopia is common or nearly universal in people older than 65 years, direct estimates of prevalence are rare,” the authors write. “The total number of people with presbyopia is primarily of interest as a precursor to the figures of greatest public health interest: the number of people with impaired vision due to uncorrected or undercorrected presbyopia and the effect on their lives.”

Brien A. Holden, Ph.D., D.Sc., of the University of New South Wales, Sydney, Australia, and colleagues analyzed multiple surveys to estimate the global prevalence of presbyopia, along with the rate at which the condition is corrected and the vision impairment caused when it is not. They then used the International Data Base of the U.S. Census Bureau to extrapolate estimates for the future.

Using projections from these surveys, the researchers estimate that 1.04 billion people globally had presbyopia in 2005, 517 million of whom had no eyeglasses or inadequate eyeglasses or spectacles. Most (386 million, or 94 percent) of the individuals whose daily tasks were impaired by uncorrected presbyopia lived in the developing world.

These estimates are based on the best available information, the authors note. “More epidemiological research in presbyopia is needed to decrease the assumptions and generalizations required for a better global estimate,” the authors write. “As more data become available, an increasingly accurate picture of the burden of presbyopia will emerge.”

The researchers predict that the worldwide prevalence of presbyopia will increase to 1.4 billion by 2020 and 1.8 billion by 2050. “Without intervention to make spectacles more accessible, the global number of individuals who will have a disability associated with uncorrected presbyopia is predicted to grow to 563 million people by 2020,” the authors conclude. “If the goal of Vision 2020 to eliminate unnecessary blindness and impaired vision, in this case due to uncorrected refractive error, is to be achieved, planning will have to include the provision of human resources, affordable spectacles and systems of delivery for these half-billion people in need.”
(Arch Ophthalmol. 2008;126[12]:1731-1739.)

Editor’s Note: This work was supported by a public health grant from the Institute for Eye Research. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Archives of Ophthalmology

Diabetics may soon be able to wear contact lenses that continuously alert them to variations in their glucose levels by changing colours – replacing the need to routinely draw blood throughout the day.

The non-invasive technology, developed by Chemical and Biochemical Engineering professor Jin Zhang at The University of Western Ontario, uses extremely small nanoparticles embedded into the hydrogel lenses. These engineered nanoparticles react with glucose molecules found in tears, causing a chemical reaction that changes their colour.

Zhang received $216,342 from the Canada Foundation for Innovation (CFI) this morning to further develop technologies using multifunctional nanocomposites.

These technologies have vast potential applications beyond biomedical devices, including for food packaging. For example, nanocomposite films can prevent food spoilage by preventing oxygen, carbon dioxide and moisture from reaching fresh meats and other foods, or by measuring pathogenic contamination; others can make packaging increasingly biodegradable.

Overall, Western was awarded $2,659,595 for 12 projects from the CFI’s Leaders Opportunity Fund.

Source: Douglas Keddy

University of Western Ontario

Two teams of experts in Belfast are working to help stop the suffering of thousands of babies1 affected by a condition which causes blindness, thanks to funding from Sussex-based children’s charity Action Medical Research.

The teams from Queen’s University Belfast, are taking two different approaches to a condition called Retinopathy of Prematurity (ROP) which can lead to blindness in premature babies, putting the youngest, sickest and smallest babies most at risk, including over 3,000 babies2,3 who are born more than 12 weeks early each year in the UK.4

ROP is caused by blood vessels in the eye growing abnormally and causing damage to the retina – the light-sensitive inner lining of the eye. Evidence suggests it develops in two stages:

– Stage 1. Premature babies have poorly developed lungs and need extra oxygen to help them breathe. Unfortunately the blood vessels that supply the eye’s light-sensitive retina are damaged by this additional oxygen and stop growing properly, meaning the retina does not get enough nutrients.

– Stage 2. Eventually, in response to this damage, new vessels grow, in an attempt to rescue the retina, but they are abnormal and actually damage the eye, causing vision loss.

The first team, led by Dr Denise McDonald, has the ultimate aim of tackling the disease at a very early stage, which will minimise the damaging effects of ROP.

The second team, led by Dr Derek Brazil, is investigating whether stem cells from babies’ own umbilical cords might have the power to repair their damaged eyes and save their sight.

Dr Alexandra Dedman, Senior Research Evaluation Manager from Action Medical Research, said: “We are delighted to be funding these two expert research teams in Belfast who both have longstanding track records, recognised internationally. Their work in this area has the potential to change the lives of babies around the world suffering from this condition.”

About one in ten babies with ROP develops severe disease, which threatens his or her sight. If this is detected early enough, laser treatment can save the most important part of a baby’s vision – the sharp, central vision we need to look straight ahead. However, this causes permanent loss of a baby’s peripheral vision and may induce short-sightedness. What’s more, it doesn’t always work, meaning some babies still go blind.

Dr Brazil believes it may be possible to protect babies from ROP, and save their sight, by treating them with a special type of stem cell taken from their own umbilical cords. Dr Brazil and his colleagues Dr Michelle Hookham, Dr Reinhold Medina and the Centre Director Professor Alan stitt, were awarded a two-year grant of ??124,652 by Action Medical Research, to undertake this important work.

He said: “We hope our laboratory work will reveal whether vascular stem cells have the potential to repair damage to babies’ eyes and save their sight. If so, it is possible that in the future vascular stem cells could be taken from a baby’s own umbilical cord just after birth and then grown in the laboratory in case treatment is needed.

Taking a different approach, Dr McDonald and her team are exploring a key step in the early stages of the disease process. While laser treatment tackles stage 2 of the disease process, by stopping abnormal blood vessels from growing, by this stage the disease can already be quite severe.

Dr McDonald and her team are looking for possible new treatments which will protect the retinal blood vessels from the effect of high oxygen which occurs in stage 1.

Evidence suggests that certain cofactors protect and encourage normal growth of the delicate blood vessels that supply the retina, as long as they are present in sufficient quantities. In contrast, low levels of these cofactors seem to be linked to the destruction of blood vessels. The researchers are investigating the role of specific cofactors and ways to enhance their function as a possible treatment for ROP.

Dr Denise McDonald and her colleague, Dr Tom Gardiner, were awarded a two-year research grant of ??112,923 from Action Medical Research for the project.

Both Dr Brazil’s and Dr McDonald’s teams are based at the Centre for Vision and Vascular Science at Queen’s University Belfast, which contains state-of-the art facilities and equipment. The centre has a long history of successful research into many of the leading causes of vision loss. Both projects involve collaboration with Dr Eibhlin McLoone, consultant paediatric ophthalmologist at the Royal Victoria Hospital.

References

1. Gilbert C. Retinopathy of Prematurity: a global perspective of the epidemics, population of babies at risk and implications for control. Early Hum Dev 2008; 84(2): 77-82.

2. National Eye Institute, National Institutes of Health, USA. Facts about retinopathy of prematurity (ROP). Website accessed 7 January 2011. See here.

3. Drack A. Retinopathy of Prematurity. Adv Pediatr 2006; 53:211-26.

4. Office of National Statistics. Preterm births 2005. See here website accessed 6 Jan 2011.

5. MedlinePlus. Retinopathy of Prematurity. Website accessed 7 January 2011. See here.

Source:

Action Medical Research

All vision, including reading this sentence, depends on a constant series of infinitesimal jumps by the eyeball that centers the retina on target objects — words or phrases in the case of reading. Such jumps, or saccades, are critical to vision because only the small central region of the retina, called the fovea, produces the clear image necessary for perception. Such saccades take place several times a second and are generated within a brain region known as the frontal eye field (FEF).

In studies with monkeys, Robert Schafer and Tirin Moore have taken an important step in understanding how circuitry of the FEF generates saccades — with the FEF’s attentional circuitry governing the motor circuitry that produces saccades. The researchers published their findings in the November 8, 2007, issue of the journal Neuron, published by Cell Press.

In a preview of the paper in the same issue of Neuron, Stefan Everling wrote that the researchers’ findings “are exciting, because they demonstrate that attention and action interact more closely in the FEF than previously thought, and they suggest a mechanism by which attention can modulate saccade motor commands.” Everling is at the University of Western Ontario in Canada.

In their experiments, Schafer and Moore took advantage of a well-known optical phenomenon involving the influence of the motion of a drifting grating on saccades that target the grating. The moving grating causes a motion-induced bias of saccades; for example, if the eye makes a saccade to a grating that is drifting upward, that saccade to the grating is biased to land higher than it would if the grating were stationary.

The researchers trained monkeys to shift their gaze to such moving gratings upon command, in return for a juice reward. During the experiments, the researchers used eyetracking to precisely measure the direction of the animals’ gaze. After measuring how the saccades were influenced by the grating motion, the researchers then electrically “microstimulated” the FEF. They then analyzed how such microstimulation affected the saccades to moving gratings.

The researchers said their analyses “indicate that the attentional effects of microstimulation determine the metrics of concurrently planned saccades, causing them to be more strongly influenced by the visual target features.” They wrote that even though the two roles of FEF circuitry — attention and motor — can be experimentally teased apart, “our results suggest that the saccadic role depends on the attentional role to select the features of the visual target and the best movement to foveate it.”

The researchers include Robert J. Schafer and Tirin Moore, of the Department of Neurobiology, Stanford University School of Medicine, Stanford, CA, USA.

Source: Cathleen Genova

Cell Press