Cataract may Occur in Children Too, Say Doctors

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Posted on 8th January 2014 by Pacific ClearVision Institute in Cataracts |General

Cataract might strike kids and require a far more complicated treatment, say doctors.

“A malformed lens in a developing foetus is the cause of cataract in infants. It is relatively rare, but I receive about 10 to 15 cases a year,” said Sanjay Dhawan, director ophthalmology at the Fortis Hospital.

According to doctors, it was very important to detect paediatric cataract at an early stage, as the retinal image becomes so distorted that a permanent loss of vision might occur without early treatment.

Dhawan said: “Children with cataract might eventually need eye muscle surgery for crossed eyes. In cases of congenital cataract, we do not expect the baby to have 100 percent vision, they have to be satisfied with 70 to 80 percent vision.”

However, cataract surgery in children was not very painful, said the doctor.

“As a precautionary measure, parents must get neonatal eye examination of their children done,” adds Dhawan.

Eyes may Now be Immune to Cataract

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Posted on 8th January 2014 by Pacific ClearVision Institute in Cataracts |General

Cataract may now be prevented by detecting the activation mechanism of a protective protein that prevents diseases of the human eye, thanks to researchers.

The lens of the human eye is made up of a highly concentrated protein solution that imparts the eye its high refractive power. Yet, despite this high protein content the ocular lens must remain clear and transparent.

To this end ocular lens cells have developed a remarkable strategy: They have thrown overboard the complex machinery present in all other cells of the human body for building up and breaking down proteins. Instead, lens proteins are created only once in a lifetime – during embryonic development.

In 2009, Johannes Buchner, professor for biotechnology at the Technische Universitaet Muenchen collaborated with Sevil Weinkauf, professor for electron microscopy at the Technische Universitaet Muenchen, and helped the first part of the aB-crystallin puzzle fall into place.

The team successfully deciphered the molecular structure of the most important form of this versatile protein – a molecule comprising 24 subunits. Under normal conditions, i.e. when the cell is not exposed to stress, this complex is the most common variant.

However, it is merely an idle form that contributes little to the prevention of clumping in other proteins. It was clear that there must be another molecular switch that triggers the protective protein.

It is this trigger mechanism that the team headed by Buchner and Weinkauf uncovered now. When a cell is exposed to stress, for instance when subjected to heat, phosphate groups are attached to a specific region of the protein.

The negative charges of these phosphates break the links between the subunits and the large complexes consequently disintegrate into numerous smaller ones of only six or twelve subunits each.

As a result of this breakup, the regions at the ends of the complexes become more flexible allowing the molecules to dock up with different partners, thereby preventing them from clumping – the protective protein is now active.

The study has been published in Proceedings of the National Academy of Sciences.

Study Finds Medicare Patients Are Increasingly Conducting Consultations Before Cataract Surgery

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Posted on 8th January 2014 by Pacific ClearVision Institute in Cataracts |General

A study finds preoperative consultations before cataract surgery became more common for Medicare patients despite no clear guidelines about when to require such a service, hinting at unnecessary use of health care resources. The study was published by JAMA Internal Medicine, a JAMA Network publication.

Preoperative medical consultation is a common health care service that can be billed separately to Medicare. There is little information about how often preoperative consultation is performed among the large numbers of patients in the United States who undergo elective, low-risk surgical procedures that may not require routine consultation, and how the referral for such consultation varies by patient, facility and geographic region, according to the study background.

Stephan R. Thilen, M.D., M.S., of the University of Washington, Seattle, and colleagues measured consultations performed by family practitioners, general internists, pulmonologists, endocrinologists, nurse practitioners or anesthesiologists as early as 42 days before cataract surgery.
Study Finds Medicare Patients Are Increasingly Conducting Consultations Before Cataract Surgery

Researchers analyzed a 5 percent sample of Medicare part B claims, which included 556,637 patients 66 years or older who had cataract surgery from 1995 to 2006.

The study findings indicate preoperative consultations became more common, increasing from 11.3 percent in 1998 to 18.4 percent in 2006. Older patients (age 75 to 84 years) were more likely to have a consultation than patients between age 66 to 74 years, while patients who were black or lived in a rural area were less likely to receive a consultation. Those patients who had their cataract surgery in an inpatient or outpatient hospital had higher odds of having a consultation than those whose surgery was performed in an office.

Patients who had an anesthesiologist involved with their care (either personally administering it or medically directing or supervising certified registered nurse anesthesists) also had higher odds of having a preoperative consultation. Living in the northeast also meant higher odds that a patient would have a consultation compared with patients living in the South or West.

“This large retrospective study suggests that there was substantial use of preoperative medical consultation for cataract surgery and that referrals for consultation had increased during the study period. With the exception of age, referral for preoperative consultation seems driven primarily by nonmedical factors including practice setting, type of anesthesia provider and geographical region,” the authors conclude. “These data highlight an area of opportunity for interventions aimed at reducing unwanted practice variability in a process that has the potential to consume vast amounts of health care resources.”

Scientists Explore Link Between Cataract Surgery and Longer Life

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Posted on 8th January 2014 by Pacific ClearVision Institute in Cataracts |General

A recent study finds that people who have had cataract surgery live longer than those who choose not to undergo the procedure.

The research is drawn from data gathered in the Blue Mountains Eye Study, a population-based cohort study of vision and common eye diseases in an older Australian population.

A total of 354 persons aged 49 years and older and diagnosed with cataract-related vision impairment – some of whom had undergone surgery and others who had not – were assessed between 1992 and 2007.

Adjustments were made for age and gender as well as a number of mortality risk factors, including hypertension, diabetes, smoking, cardiovascular disease, body mass index and measures of frailty and comorbid disease. Follow-up visits took place after five and ten years since the baseline exam.

Jie Jin Wang, Ph.D., of the Westmead Millennium Institute and one of lead researchers of the study, said that their findings suggested that correcting cataract patients’ visual impairment in their daily practice results in improved outcomes beyond that of the eye and vision, and has important impacts on general health.

Wang noted one limitation of the study is that participants with cataract-related visual impairment who did not have cataract surgery could have had other health problems that prevented them from undergoing surgery, and that these other health problems could partly explain the poorer survival among non-surgical participants.

The study has been published in the journal of the American Academy of Ophthalmology.

Do Large Pupils Cause Problems After LASIK?

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Posted on 8th January 2014 by Pacific ClearVision Institute in General |LASIK

It’s been suggested that people with large pupils have a greater risk of glare and halos around lights at night after LASIK surgery than people with normal-sized pupils. But is that really true?

In a study published this month in Journal of Refractive Surgery, researchers analyzed 19 studies published in peer-reviewed journals since 2002 that investigated the effect of pupil size on LASIK outcomes.

None of the reviewed studies showed a correlation between pre-operative pupil size and persistent night vision complaints after LASIK surgery when the surgical ablation zone (the area of the cornea that’s reshaped by the laser) was 6.0 mm in diameter or larger and the follow-up period was at least three months.

Studies that did find a correlation between pupil size and night vision complaints after LASIK included patients with ablations smaller than 6.0 mm or did not specify ablation size. Studies with mixed conclusions either followed patients for fewer than three months or found that patients showed an improvement in night vision over time.

The researchers concluded that in these studies, patients with large pupils did not appear to have an increased risk of night vision problems after modern LASIK surgery (which typically involves a laser ablation zone of 6.0 mm or larger), when compared with patients with smaller pupils and when patients were examined after a follow-up period of three months or longer.

Small Vessel Changes in Eye, Kidney Provide Clues to Risky Heart Rhythm

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Posted on 8th January 2014 by Pacific ClearVision Institute in General |Retina

People with damage in the small blood vessels of the retina and kidneys are at increased risk to develop the most common type of abnormal heart rhythm, according to research presented at the American Heart Association’s Scientific Sessions 2013.

Atrial fibrillation raises the risk of stroke and causes heart-related chest pain or heart failure in some people.

Researchers in the Atherosclerosis Risk in Communities Study (ARIC) followed 10,009 middle-aged people for an average 13.6 years. Atrial fibrillation developed at a rate of:

- 5.7 incidents per 1,000 person-years in those with no retina or kidney changes.
- 8.9 incidents per 1,000 person-years in those with signs of small vessel damage in the retina, such as micro-bleeds or micro-aneurysms.
- 16.8 incidents per 1,000 person-years in those with signs of vessel damage in the kidneys, allowing tiny amounts of protein to be released into their urine (micro-albuminuria).
- 24.4 incidents per 1,000 person-years in those with both retinopathy and micro-albuminuria.

Though reasons for the association are unclear, changes in other vascular beds may serve as a representation of coronary micro-vascular changes and the observed association may be mediated via inflammation, endothelial dysfunction, autonomic dysfunction, and electro-mechanical remodeling, the researchers said.

Can Eyes Help Diagnose Alzheimer’s Disease?

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Posted on 8th January 2014 by Pacific ClearVision Institute in General |Retina

An international team of researchers studying the link between vision loss and Alzheimer’s disease report that the loss of a particular layer of retinal cells not previously investigated may reveal the disease’s presence and provide a new way to track disease progression.

The researchers, from Georgetown University Medical Center (GUMC) and the University of Hong Kong, examined retinas from the eyes of mice genetically engineered to develop Alzheimer’s disease (AD). They presented their findings today at Neuroscience 2013, the annual meeting of the Society for Neuroscience.

“The retina is an extension of the brain so it makes sense to see if the same pathologic processes found in an Alzheimer’s brain are also found in the eye,” explains R. Scott Turner, MD, PhD, director of the Memory Disorders Program at GUMC and the only U.S. author on the study. “We know there’s an association between glaucoma and Alzheimer’s in that both are characterized by loss of neurons, but the mechanisms are not clear.”

Turner says many researchers increasingly view glaucoma as a neurodegenerative disorder similar to AD.

Most of the research to date examining the relationship between glaucoma and Alzheimer’s focused on the retinal ganglion cell layer, which transmits visual information via the optic nerve into the brain. Before that transmission happens, though, the retinal ganglion cells receive information from another layer in the retina called the inner nuclear layer.

In their study, the researchers looked at the thickness of the retina, including the inner nuclear layer (not previously study in this setting) and the retinal ganglion cell layer. They found a significant loss of thickness in both. The inner nuclear layer had a 37 percent loss of neurons and the retinal ganglion cell layer a 49 percent loss, compared with healthy, age-matched control mice.

In humans, the structure and thickness of the retina can be readily measured using optical coherence tomography. Turner says this new tool is increasing finding applications in research and clinical care.

“This study suggests another path forward in understanding the disease process and could lead to new ways to diagnose or predict Alzheimer’s that could be as simple as looking into the eyes,” Turner says. “Parallel disease mechanisms suggest that new treatments developed for Alzheimer’s may also be useful for glaucoma.”

Bright Eyes: Reindeers’ Eyes Change from Blue to Gold With Arctic Seasons

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Posted on 8th January 2014 by Pacific ClearVision Institute in General |Retina

Researchers have discovered the eyes of Arctic reindeer change colour through the seasons from gold to blue, adapting to extreme changes of light levels in their environment and helping detect predators.

The Biotechnology and Biological Sciences Research Council (BBSRC) funded team from UCL (University College London), and the University of Tromsø, Norway, showed that the colour change helps reindeer to see better in the continuous daylight of summer and continuous darkness of Arctic winters, by changing the sensitivity of the retina to light.

Arctic reindeer, like many animals, have a layer of tissue in the eye called the tapetum lucidum (TL) which lies behind the retina and reflects light back through it to enhance night vision.

By changing its colour the TL reflects different wavelengths of light.

In the bright light of summer the TL in Arctic reindeer is gold, similar to many other mammals, which reflects most light back directly through the retina.

However by winter it has changed to a deep blue which reflects less light out of the eye.

This change scatters more light through photoreceptors at the back of the eye, increasing the sensitivity of the retina in response to the limited winter light

The team believes this would be an advantage in the prolonged murk of winter, allowing reindeer to more easily detect moving predators and forage.

Lead researcher Professor Glen Jeffery from UCL, said: “This is the first time a colour change of this kind has been shown in mammals. By changing the colour of the TL in the eye reindeer have flexibility to cope better with the extreme differences between light levels in their habitat between seasons.

“This gives them an advantage when it comes to spotting predators, which could save their lives.”

The colour change may be caused by pressure within the eyes. In winter pressure in the reindeers’ eyes is increased, probably caused by permanent pupil dilation, which prevents fluid in the eyeball from draining naturally. This compresses the TL, reducing the space between collagen in the tissue and thus reflecting the shorter wavelengths of the blue light common in Arctic winters.

Previous work from Professor Jeffery and Norwegian colleagues from Tromso had shown that Arctic reindeer eyes can also see ultraviolet, which is abundant in Arctic light but invisible to humans, and that they use this to find food and see predators.

The blue reflection from the winter eye is likely to favour ultra-violet sensitivity.

3-D Tissue Printing: Cells from the Eye Inkjet-Printed for the First Time

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Posted on 8th January 2014 by Pacific ClearVision Institute in General |Retina

A group of researchers from the UK have used inkjet printing technology to successfully print cells taken from the eye for the very first time.

The breakthrough, which has been detailed in a paper published today, 18 December, in IOP Publishing’s journal Biofabrication, could lead to the production of artificial tissue grafts made from the variety of cells found in the human retina and may aid in the search to cure blindness.

At the moment the results are preliminary and provide proof-of-principle that an inkjet printer can be used to print two types of cells from the retina of adult rats–ganglion cells and glial cells. This is the first time the technology has been used successfully to print mature central nervous system cells and the results showed that printed cells remained healthy and retained their ability to survive and grow in culture.

Co-authors of the study Professor Keith Martin and Dr Barbara Lorber, from the John van Geest Centre for Brain Repair, University of Cambridge, said: “The loss of nerve cells in the retina is a feature of many blinding eye diseases. The retina is an exquisitely organised structure where the precise arrangement of cells in relation to one another is critical for effective visual function.”

“Our study has shown, for the first time, that cells derived from the mature central nervous system, the eye, can be printed using a piezoelectric inkjet printer. Although our results are preliminary and much more work is still required, the aim is to develop this technology for use in retinal repair in the future.”

The ability to arrange cells into highly defined patterns and structures has recently elevated the use of 3D printing in the biomedical sciences to create cell-based structures for use in regenerative medicine.

In their study, the researchers used a piezoelectric inkjet printer device that ejected the cells through a sub-millimetre diameter nozzle when a specific electrical pulse was applied. They also used high speed video technology to record the printing process with high resolution and optimised their procedures accordingly.

“In order for a fluid to print well from an inkjet print head, its properties, such as viscosity and surface tension, need to conform to a fairly narrow range of values. Adding cells to the fluid complicates its properties significantly,” commented Dr Wen-Kai Hsiao, another member of the team based at the Inkjet Research Centre in Cambridge.

Once printed, a number of tests were performed on each type of cell to see how many of the cells survived the process and how it affected their ability to survive and grow.

The cells derived from the retina of the rats were retinal ganglion cells, which transmit information from the eye to certain parts of the brain, and glial cells, which provide support and protection for neurons.

“We plan to extend this study to print other cells of the retina and to investigate if light-sensitive photoreceptors can be successfully printed using inkjet technology. In addition, we would like to further develop our printing process to be suitable for commercial, multi-nozzle print heads,” Professor Martin concluded.

Critical Gene in Retinal Development and Motion Sensing Identified

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Posted on 8th January 2014 by Pacific ClearVision Institute in General |Retina

Our vision depends on exquisitely organized layers of cells within the eye’s retina, each with a distinct role in perception. Johns Hopkins researchers say they have taken an important step toward understanding how those cells are organized to produce what the brain “sees.” Specifically, they report identification of a gene that guides the separation of two types of motion-sensing cells, offering insight into how cellular layering develops in the retina, with possible implications for the brain’s cerebral cortex.

A report on the discovery is published in the Nov. 1 issue of the journal Science.

“The separation of different types of cells into layers is critical to their ability to form the precise sets of connections with each other — the circuitry — that lets us process visual information,” says Alex Kolodkin, Ph.D., a professor in the Johns Hopkins University School of Medicine’s Solomon H. Snyder Department of Neuroscience and an investigator at the Howard Hughes Medical Institute. “There is still much to learn about how that separation happens during development, but we’ve identified for the first time proteins that enable two very similar types of cells to segregate into their own distinct neuronal layers.”

Kolodkin’s research group specializes in studying how circuitry forms among neurons (brain and nerve cells). Past experiments revealed that two types of proteins, called semaphorins and plexins, help guide this process. In the current study, Lu Sun, a graduate student in Kolodkin’s laboratory, focused on the genes that carry the blueprint for these proteins in two of the 10 layers of cells in the mammalian retina.

Those two layers are made up of so-called starburst amacrine cells (SACs). One type of SAC, known as “Off,” detects motion by sensing decreases in the amount of light hitting the retina, while the other type, “On,” detects increases in light. Sun examined the amounts of several semaphorin and plexin proteins being made by each type of cell, and found that only the “On” SACs were making a semaphorin called Sema6A. Sema6A can only work in the retina by interacting with its receptor, a plexin called PlexA2, but Sun found both types of SAC were churning out roughly equal amounts of PlexA2.

Reasoning that Sema6A might be the key difference that enabled the “On” and “Off” SACs to segregate from one another, Kolodkin’s team analyzed mice in which the genes for either Sema6A, PlexA2 or both could be switched off, and looked at the effects of this manipulation on their retinas. “Knocking out” either gene during development led the “On” and “Off” layers to run together, the team found, and caused abnormalities in the “On” SACs’ tree-like extensions. However, the “Off” SACs, which hadn’t been using their Sema6A gene in the first place, still looked and functioned normally.

“When signaling between Sema6A and PlexA2 was lost, not only was layering compromised, but the ‘On’ SACs lost both their distinctive symmetrical appearance, and, importantly, their motion-detecting ability,” Sun says. “This is evidence that the beautiful symmetric shape that gives starburst amacrine cells their name is necessary for their function.”

Adds Kolodkin, “We hope that learning how layering occurs in these very specific cell types will help us begin sorting out how connections are made not just in the retina, but also in neurons throughout the nervous system. Layering also occurs in the cerebral cortex, for example, which is responsible for thought and consciousness, and we really want to know how this is organized during neural development.”

Other authors on the report are Zheng Jiang, Randal Hand, Colleen M. Brady, Ryota L. Matsuoka and King-Wai Yau of the Johns Hopkins University School of Medicine, and Michal Rivlin-Etzion and Marla B. Feller of the University of California, Berkeley.

This work was supported by the National Institute of Neurological Disorders and Stroke (grant number NS35165), the National Eye Institute (grant numbers EY06837, EY019498 and EY013528), the Human Frontier Science Program, the Weizmann Institute’s National Postdoctoral Award Program for Advancing Women in Science, and the Edmond and Lily Safra (ELSC) Fellowship for Postdoctoral Training in Brain Science.