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Ophthalmology and Optometry
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Scientists Develop Telescopic Contact Lenses PDF
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Ophthalmology and Optometry
Thursday, 05 March 2015

Telescopic Contact LensLast month researchers unveiled a new prototype of telescopic contact lens giving hope for better, stronger vision. They also showed  complementary smart glasses that recognize winks and ignore blinks, allowing wearers of the contact lenses to switch between normal and magnified vision.

"We think these lenses hold a lot of promise for low vision and age-related macular degeneration (AMD)," says Tremblay, a researcher in the team. "It's very important and hard to strike a balance between function and the social costs of wearing any kind of bulky visual device. There is a strong need for something more integrated, and a contact lens is an attractive direction. At this point this is still research, but we are hopeful it will eventually become a real option for people with AMD."

The first iteration of the telescopic contact lens--which magnifies 2.8 times--was announced in 2013. Since then the scientists behind the project have been fine-tuning the lens membranes and developing accessories to make the eyewear smarter and more comfortable for longer periods of time, and thus more usable in every day life.

The contacts work by incorporating a very thin reflective telescope inside a 1.55mm thick lens. Small mirrors within bounce light around, expanding the perceived size of objects and magnifying the view, so it's like looking through low magnification binoculars.

At this time, the telescopic contacts are made using a rigid lens known as a scleral lens--larger in diameter than the typical soft contacts you might be used to and valuable for special cases, such as for people with irregularly shaped corneas. Although large and rigid, scleral lenses are safe and comfortable for special applications, and present an attractive platform for technologies such as optics, sensors, and electronics like the ones in the telescopic contact lens, says Tremblay.

The final lenses are made from several precision cut and carefully assembled pieces of plastics, aluminum mirrors, and polarizing thin films, along with biologically safe glues.

Since the eye needs a steady supply of oxygen, the scientific team has spent the last couple of years making the lenses more breathable--a critical requirement. To achieve oxygen permeability, they are incorporating tiny air channels roughly 0.1mm wide within the lens to allow oxygen to flow around and underneath the complex and normally impermeable optical structures to get to the cornea.

Image quality and oxygen permeability in the lenses are ongoing challenges and objects of research, but results are improving as the mechanical and manufacturing processes are refined and better understood, say the scientists.

The researchers have also developed a novel method to electronically switch the wearer's view between normal, or unmagnified vision and telescopic. This switching functionality is crucial for the lenses to be widely useful for non-AMD sufferers who will be able to have magnification "on demand". In the system electronic glasses use a small light source and light detector to recognize winks and ignore blinks. The wearer will wink their right eye for magnification, and left eye for normal vision.

The glasses work by electronically selecting a polarization of light to reach the contact lens. The contact lens allows one type of polarization in the 1x aperture and another in the 2.8x aperture. Thus, the user sees the view where the polarization of the glasses and contact lens aperture match.

There are glasses already on the market for people with AMD that have mounted telescopes, but they tend to look bulky and interfere with social interaction. They also do not track eye movement, so you have to position your eyes and tilt your head to use them.

The combination of the telescopic contact lenses and optional blink-controlled eyewear represent a huge leap in functionality and usability in vision aid devices and a major feat for optics research.

 
Ortho-K Custom-made CLs Slow Progress of Myopia in Children PDF
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Ophthalmology and Optometry
Friday, 27 February 2015

myopia childrenA technique called orthokeratology ("Ortho-K"), using custom-made contact lenses to shape the growing eye, has a significant effect in slowing the progression of myopia (nearsightedness) in children, according to a research review in the March issue of Optometry and Vision Science, official journal of the American Academy of Optometry.

Led by Xing-Rong Wang, MD, of the Affiliated Eye Hospital of Shangdong University of Traditional Chinese Medicine in Jinan, China, the researchers analyzed pooled data from previous studies of Ortho-K. They concluded that orthokeratology does certainly slow myopia progression and retard the axial length growth of the eye. Dr Wang and colleagues analyzed seven previous studies of orthokeratology to treat myopia (nearsightedness) in children. Myopia is one of the most common eye disorders worldwide, with a reported prevalence of 20 to 50 percent in the United States and Europe, and 70 percent or higher in East Asia. Of the seven studies, five were performed in East Asia.

Ortho-K is a relatively new treatment approach, in which the child wears customized contact lenses overnight. Over time, the Ortho-K lenses act to guide eye growth--similar to the use of a dental "retainer" to straighten the teeth. Previous studies have reported encouraging results with Ortho-K in slowing myopia progression.

The seven studies included data on 435 children with mild to moderate myopia, aged six to 16 years. All studies assessed axial length, or the length of the eye from front to back. This is a key measure of eye growth, specifically of interest related to myopia development. The researchers used a method called meta-analysis to pool the study results from the publications they reviewed.

As expected, with or without orthokeratology, axial length increased as the children grew. However, after two years, the increase in axial length was significantly slower in children treated with Ortho-K. The average (weighted mean) difference between groups was about one-fourth of a millimeter. That small but significant change was consistent with the reported effects of Ortho-K in slowing myopia progression. An alternative measure of eye growth (vitreous chamber depth) showed a similar difference between groups.

For reasons that are not yet entirely clear, childhood myopia has increased to epidemic proportions in recent years, especially in Asia. Myopia persists into adulthood and, in the more severe cases, is a risk factor for eye diseases such as cataracts, glaucoma, and retinal detachments.

Eye and vision researchers have been working on new optical treatment approaches to slow myopia progression. Ortho-K is one promising approach; others include contact lens designs that modify the focus on the peripheral retina.

The new review and meta-analysis supports the effectiveness of Ortho-K in producing at least some reduction in the rate of progressive myopia. The questions remain as to the mechanism by which Ortho-K works to control myopic eye growth. Dr Wang and coauthors emphasize the need for additional studies to address this issue, as well as large-scale randomized trials to assess its long-term benefits.

 
Optic Nerve May Help Predict Stroke PDF
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Ophthalmology and Optometry
Friday, 13 February 2015

Using optic ultrasound to measure the sheath of a nerve that connects the eye and brain can help identify acute stroke patients most at risk of dying within days or months, according to research presented at the American Stroke Association's International Stroke Conference 2015.

The new study aimed to quickly and noninvasively identify stroke patients who are at risk from increased pressure inside the skull – which is thought to reflect stroke severity and is the major cause of death. Measuring the thickness of the optic nerve sheath may be a simple test for increased intracranial pressure, said Vishnumurthy S. Hedna, M.D., lead researcher and assistant professor of neurology at the University of Florida College of Medicine in Gainesville, Fla.

The study involved 86 patients at the University of Florida's Shands Hospital who were suspected of having a buildup of pressure in the skull after their stroke. Researchers used ocular ultrasound (ultrasound assessment of the eyes) to measure the sheath that encases the optic nerve.

For patients who later died of a stroke due to a blood vessel blockage, average diameter of the nerve sheath was 5.82 millimeters, versus 5.33 millimeters in those who survived. In patients with a bleeding stroke, average diameter was 6.23 millimeters for those who died, versus 5.72 for survivors.

For every millimeter bigger the nerve sheath diameter was, the risk of death within six months was four times as high in patients whose stroke was due to a blood vessel blockage, and six times as high in patients who had a bleeding stroke. Most of the deaths occurred within a month of patients' hospitalization. The study also suggested that the larger the nerve sheath measurement, the more disabled a patient was likely to be six months later.

 
"On Command" Shades Developed PDF
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Ophthalmology and Optometry
Monday, 09 February 2015

on command shadesImagine eyeglasses that can go quickly from clear to shaded and back again when you want them to, rather than passively in response to changes in light. Scientists report a major step toward that goal, which could benefit pilots, security guards and others who need such control, in the journal ACS Applied Materials & Interfaces.

In the study, led by Anna Österholm in John Reynolds' group at the Georgia Institute of Technology, the researchers point out that most transitional lenses now on the market don't meet many users' needs. When wearers are driving or wearing a baseball cap, for example, the lenses stay clear rather than switching to a darker shade even in broad daylight. Also, the majority of available versions don’t block out the harshest light, such as bright light reflected off snow. And the change from colored to clear can take several minutes, which has safety implications for certain users including airline pilots. Reynolds' team wanted to find a way to solve these issues.

The researchers designed a new kind of lens that can switch within seconds from clear to darkly shaded and back again in response to a small electrical charge that a wearer could control. They can also fine-tune the color of the lenses to match the full range of hues used in commercial sunglasses. To make the lenses, they say they used a method that could be easily scaled up for manufacturing.

 
Novel Eye-Tracking Technology Detects Concussions PDF
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Ophthalmology and Optometry
Friday, 06 February 2015

concussionsNew research could move the medical community one step closer toward effectively detecting concussion and quantifying its severity. Neuroscientists and concussion experts, in a study published in Journal of Neurotrauma, present a unique, simple and objective diagnostic tool for concussion that can be utilized in the emergency room or, one day, on the sidelines at sporting events. The study utilized a novel eye-tracking device to effectively measure the severity of concussion or brain injury in patients presenting to emergency departments following head trauma.

The eyes have served as a window into the brain, with disconjugate eye movements -- eyes rotating in opposite directions – considered a principal marker for head trauma as early as 3,500 years ago. Current estimates by optometrists suggest that up to 90 percent of patients with concussions or blast injuries exhibit dysfunction in their eye movements.

Unfortunately, the “state-of-the-art” tool to detect eye conjugacy is asking a patient to follow along with a physician's finger, according to a researcher. The eye-tracking technology used in this study was originally developed to assess eye movement in veterans of the long Middle East conflicts suspected of suffering from traumatic brain injury (TBI), concussion or other forms of brain injury. 

In this new study, researchers compared 64 healthy control subjects to 75 patients who had experienced trauma. They tracked and compared the movements of patients' pupils for over 200 seconds while watching a music video. All participants were between 18 and 60 years of age.

The study showed that 13 trauma patients who had hit their heads and had CT scans showing new brain damage, as well as 39 trauma patients who had hit their heads and had normal CT scans, had significantly less ability to coordinate their eye movements than normal, uninjured control subjects. 23 trauma subjects who had bodily or extremity injuries but did not require head CT scans had similar abilities to coordinate eye movements as normal uninjured controls.

Among patients who had hit their heads and had normal CT scans, most were slightly worse at 1-2 weeks after the injury, and subsequently recovered about one month after the injury. Among all trauma patients, the severity of concussive symptoms correlated with severity of disconjugacy.

Those offering support for Dr. Samadani’s research include Richard G. Ellenbogen, MD, The Theodore S. Roberts Endowed Chair and professor and chairman of the Department of Neurological Surgery at University of Washington Medicine and co-chair of the Head, Neck and Spine Committee of the National Football League. Dr. Ellenbogen was not involved in the study.

The new study of non-military, civilian trauma patients visiting the emergency department builds on recent research which found that the use of this novel eye-tracking technology could reveal edema, or swelling, in the brain as a potential biomarker for assessing brain function and monitoring recovery in people with head injuries. That study looked exclusively at military veterans.

Future work aims to replicate eye-tracking's diagnostic potential for head injuries on a larger scale in Iraq and Afghanistan veterans with post-concussive syndrome and post-blast military brain injury.

 
Researchers Advance the Science Behind Treating Patients with Corneal Blindness PDF
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Ophthalmology and Optometry
Tuesday, 03 February 2015

Corneal BlindnessResearchers in the Cedars-Sinai Board of Governors Regenerative Medicine Institute in US have devised a novel way to generate transplantable corneal stem cells that may eventually benefit patients suffering from life-altering forms of blindness. Scientists used human corneal cells to generate pluripotent stem cells that have a capacity to become virtually any body cell. Then, putting these cells on natural scaffolds, researcher's facilitated differentiation of these stem cells back to corneal cells.

"Our research shows that cells derived from corneal stem cells are attractive candidates for generating corneal cells in the laboratory," said Alexander Ljubimov, PhD, director of the Eye Program at the Board of Governors Regenerative Medicine Institute and principal investigator on this research study.

This research, published in the journal Stem Cells Translational Medicine, marks an important first step toward creating a bank of corneal stem cells that may potentially benefit patients who suffer from many forms of corneal blindness. The group is now working to optimize the process with National Institutes of Health funding.

Corneal deficiencies may have genetic or inflammatory roots or be caused by injuries, like burns to the skin in occupational accidents. They result in damage or death of stem cells that renew the outermost part of the cornea. If left untreated, they often cause compromised vision or blindness. More than 3 million individuals worldwide are affected by corneal blindness.

 
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