FOLLOW US ON... FEEDBACK

Home >> Industry News >> Ophthalmology & Optometry
sideview vmo3D sideview vmo3D 30 day free trial
Ophthalmology and Optometry
  • Also available via:


Major Cause of Blindness Linked to Calcium Deposits PDF
Submit Your News
Ophthalmology and Optometry
Friday, 23 January 2015

MaculaMicroscopic spheres of calcium phosphate have been linked to the development of age-related macular degeneration (AMD), a major cause of blindness. The latest research, published in Proceedings of the National Academy of Sciences, has implicated tiny spheres of mineralised calcium phosphate, 'hydroxylapatite', in AMD progression. This not only offers a possible explanation for how AMD develops, but also opens up new ways to diagnose and treat the disease.

AMD is characterised by a build-up of mainly protein and fat containing deposits called 'drusen' in the retina, which can prevent essential nutrients from reaching the eye's light-sensitive cells, 'photoreceptors'. Photoreceptors are regularly recycled by cellular processes, creating waste products, but drusen can trap this ‘junk’ inside the retina, worsening the build-up. Until now, nobody understood how drusen formed and grew to clinically relevant size.

The new study shows that tiny calcium-based hydroxyapatite, commonly found in bones and teeth, could explain the origin of drusen. The researchers believe that these spheres attract proteins and fats to their surface, which build up over years to form drusen. Through post-mortem examination of 30 eyes from donors between 43 and 96 years old, the researchers used fluorescent dyes to identify the tiny spheres, just a few microns – thousandths of a millimetre – across.

Some of the mineral spheres identified in the eye samples were coated with amyloid beta, which is linked to Alzheimer's disease. If a technique were developed to identify these spheres for AMD diagnosis, it may also aid early diagnosis of Alzheimer's. Whether these spheres are a cause or symptom of AMD is still unclear, but their diagnostic value is significant either way. As drusen are hallmarks of AMD, then strategies to prevent build-up could potentially stop AMD from developing altogether.

For more information goto: www.pnas.org/content/early/2015/01/15/1413347112

 
Chronic High Blood Pressure Increases Risk of Glaucoma PDF
Submit Your News
Ophthalmology and Optometry
Friday, 09 January 2015

A new study published in Investigative Ophthalmology & Visual Science (IOVS) has found that chronic (long term) hypertension increases a person’s susceptibility to glaucoma. These results suggest that doctors should consider a patient’s blood pressure levels in managing the potentially blinding eye disorder.

Glaucoma, the second leading cause of blindness in the world, is a condition that occurs when too much pressure builds up inside the eye. This excess pressure pushes back against blood trying to enter the eye resulting in vision loss.

"Studies have shown that high blood pressure is a risk factor for glaucoma. But the reasons for this were never clear," said author Bang Bui, PhD, of the University of Melbourne, Australia, Department of Optometry and Vision Sciences. In the IOVS study, Chronic Hypertension Increases Susceptibility to Acute IOP Challenge in Rats, Bang and his co-authors from the University of Melbourne and School of Medicine at Deakin University, Australia, identify a reason for those observations.

Previously, it was thought that high blood pressure could counteract the high eye pressure that leads to glaucoma. This theory was supported by past research that had shown raising blood pressure for a short period of time (one hour) offered some protection against elevated eye pressure, as high blood pressure ensured that blood continued to enter the eye.

However, data gathered from large populations of glaucoma patients subsequently suggested that hypertension in young patients protects against the disorder, but is a risk factor in older patients.

One explanation of this phenomenon is that any benefit from high blood pressure counteracting high eye pressure is lost as damage to blood vessels — a consequence of hypertension — becomes more prevalent.

The authors tested this hypothesis by comparing the effect of acute (one hour) and chronic (four week) hypertension in lab rats with elevated eye pressure.

“When we raised blood pressure… for four weeks, we didn't get the same protection against eye pressure elevation as in the [one hour] case,” said Bui. “What this means is that having high blood pressure for a longer time has compromised the eye's capacity to cope with high eye pressure. It seems that hypertension might damage the blood vessels in the eye so that they can't compensate for changes in blood flow when eye pressure increases.”

This new understanding of the consequences of high blood pressure will help doctors treat patients with glaucoma. Instead of viewing hypertension as beneficial in the fight against the disorder, Bui suggests it should be identified as a risk factor. Further studies in this area might better inform how to treat patients with hypertension who also develop glaucoma. 

 
Top-Selling Eye Vitamins Found Not to Match Scientific Evidence PDF
Submit Your News
Ophthalmology and Optometry
Wednesday, 07 January 2015

Researchers have analyzed popular eye vitamins to determine whether their formulations and claims are consistent with scientific findings. They determined that some of the top-selling products do not contain identical ingredient dosages to eye vitamin formulas proven effective in clinical trials. In addition, the study found that claims made on the products' promotional materials lack scientific evidence. The results of their study were published online in Ophthalmology, the journal of the American Academy of Ophthalmology.

The leading cause of blindness among older adults in the United States is the deterioration of the eye's macula, which is the central part of the retina that enables the eye to see fine details clearly. Recommended treatment for AMD at certain stages of the disease includes nutritional supplements. The landmark Age-Related Eye Disease Study (AREDS) found in 2001 that a specific formula of nutritional supplements containing high doses of antioxidants and zinc could slow the worsening of AMD in those who have intermediate AMD and those with advanced AMD in only one eye. A follow-up study that concluded in 2011, AREDS2, determined that the formula was still effective if one ingredient, beta-carotene (a form of vitamin A), was replaced with related nutrients, lutein and zeaxanthin. Beta-carotene was substituted in AREDS2 due to its link to increased risk of lung cancer in smokers. The two studies prompted a surge in sales of eye supplements which are marketed as containing the AREDS or AREDS2 formulas.

To test whether the products are consistent with the studies' findings, researchers compared the ingredients in top-selling brands to the exact formulas proven effective by AREDS and AREDS2. The researchers – based at Yale-New Haven Hospital-Waterbury Hospital, Penn State College of Medicine, Providence VA Medical Center and Warren Alpert Medical School of Brown University – identified the five top-selling brands based on market research collected from June 2011 to June 2012, and analyzed the brands' 11 products.

They found that, while all of the products studied contained the ingredients from the AREDS or AREDS2 formulas:

  • Only four of the products had equivalent doses of AREDS or AREDS2 ingredients
  • Another four of the products contained lower doses of all the AREDS or AREDS2 ingredients
  • Four of the products also included additional vitamins, minerals and herbal extracts that are not part of the AREDS or AREDS2 formulas

In addition, while all 11 of the products' promotional materials contained claims that the supplements "support," "protect," "help" or "promote" vision and eye health, none had statements specifying that nutritional supplements have only been proven effective in people with specific stages of AMD. There were also no statements clarifying that there is insufficient evidence to support the routine use of nutritional supplements for primary prevention of eye diseases such as AMD and cataracts.

 
Retina Changes Its "Language" with Changing Brightness PDF
Submit Your News
Ophthalmology and Optometry
Wednesday, 17 December 2014

A study at the University of Tübingen highlights the intricate nature of visual responses. The findings may help to improve digital cameras as well as visual prosthetics.

Our visual abilities are astonishing: we can see in extreme situations, from a stroll under the starry sky to a ski-run in glaring sunlight. We do this effortlessly, much smoother and more stable than even the most modern digital cameras. Scientists knew that the first steps of visual processing already occur inside our eyes: The retina does not only harbor the light-sensitive receptor cells, but it also processes the incoming information and transmits it as an intricate pattern of activity via the optic nerve to the brain.

A new study now shows that this process is much more complex than previously thought. Scientists of the Werner Reichardt Centre for Integrative Neuroscience (CIN) and Bernstein Center for Computational Neuroscience at the University of Tübingen, together with colleagues from the University of Manchester, showed that the activity patterns sent to the brain – the "language" of the retina – fundamentally depends on the ambient light level in our environment. When light conditions change, the retina speaks a different language. The study was published on 8 Dec 2014 in the journal Nature Neuroscience.

 
Human Eye Can Potentially See Infrared Light PDF
Submit Your News
Ophthalmology and Optometry
Thursday, 11 December 2014

infrared lightAn international team of researchers has found that under certain conditions, the retina can sense infrared light after all. Using cells from the retinas of mice and people, and powerful lasers that emit pulses of infrared light, the researchers found that when laser light pulses rapidly, light-sensing cells in the retina sometimes get a double hit of infrared energy. When that happens, the eye is able to detect light that falls outside the visible spectrum.

The findings are published Dec. 1 in the Proceedings of the National Academy of Sciences (PNAS) Online Early Edition. Collaborators include scientists in U.S., Poland, Switzerland and Norway. The research was initiated after scientists on the research team reported seeing occasional flashes of green light while working with an infrared laser. Unlike the laser pointers used in lecture halls or as toys, the powerful infrared laser the scientists worked with emits light waves thought to be invisible to the human eye.

Normally, a particle of light, called a photon, is absorbed by the retina, which then creates a molecule called a photopigment, which begins the process of converting light into vision. In standard vision, each of a large number of photopigments absorbs a single photon. But packing a lot of photons in a short pulse of the rapidly pulsing laser light makes it possible for two photons to be absorbed at one time by a single photopigment, and the combined energy of the two light particles is enough to activate the pigment and allow the eye to see what normally is invisible.

Although the researchers are the first to report that the eye can sense light through this mechanism, the idea of using less powerful laser light to make things visible isn’t new. The two-photon microscope, for example, uses lasers to detect fluorescent molecules deep in tissues. And the researchers said they already are working on ways to use the two-photon approach in a new type of ophthalmoscope, which is a tool that allows physicians to examine the inside of the eye. The idea is that by shining a pulsing, infrared laser into the eye, doctors might be able to stimulate parts of the retina to learn more about its structure and function in healthy eyes and in people with retinal diseases such as macular degeneration.

 
Nanotubes May Restore Sight to Blind Retinas PDF
Submit Your News
Ophthalmology and Optometry
Wednesday, 10 December 2014

The aging process affects everything from cardiovascular function to memory to sexuality. Most worrisome for many, however, is the potential loss of eyesight due to retinal degeneration.

New progress towards a prosthetic retina could help alleviate conditions that result from problems with this vital part of the eye. An encouraging new study published in Nano Letters describes a revolutionary novel device, tested on animal-derived retinal models, that has the potential to treat a number of eye diseases. The proof-of-concept artificial retina was developed by an international team led by Prof. Yael Hanein of Tel Aviv University (TAU)'s School of Electrical Engineering and head of the University's Center for Nanoscience and Nanotechnology and including researchers from TAU, the Hebrew University of Jerusalem, and Newcastle University.

The researchers combined semiconductor nanorods and carbon nanotubes to create a wireless, light-sensitive, flexible film that could potentially replace a damaged retina. The researchers tested the new device with chick retinas which were not yet light sensitive to prove that the artificial retina is able to induce neuronal activity in response to light.

Patients with age-related macular degeneration (AMD), which usually affects people age 60 or older who have damage to a specific part of the retina, will stand to benefit from the nanotube device if it is proved compatible in animals over the long term.

According to TAU doctoral student and research team member Dr. Lilach Bareket, there are already medical devices that attempt to treat visual impairment by sending sensory signals to the brain. While scientists are trying different approaches to develop an implant that can "see" light and send visual signals to a person's brain, to counter the effects of AMD and related vision disorders, many of these approaches require the use of metallic parts and cumbersome wiring or result in low resolution images. The researchers set out to make a more compact device.

"In comparison with other technologies, our new material is more durable, flexible, and efficient, as well as better able to stimulate neurons," said Prof. Hanein. "We hope our carbon nanotube and semiconductor nanorod film will serve as a compact replacement for damaged retinas."

"We are still far away from actually replacing the damaged retina," said Dr. Bareket. "But we have now demonstrated that this new material stimulates neurons efficiently and wirelessly with light. If you compare this to other devices based on silicon technology, which require wiring to outside energy or light sources, this is a groundbreaking new direction."

 
<< Start < Prev 1 2 3 4 5 6 7 8 9 10 Next > End >>

Page 1 of 94