Risk for Cataract Increases with Age, but Other Factors Also Contribute

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Posted on 30th May 2012 by Pacific ClearVision Institute in Cataracts

With age comes new health challenges, especially for vision. Today, more than 22 million Americans age 40 and older have cataract, a clouding of the eye’s lens which blocks or changes the passage of light into the eye. According to the National Eye Institute, by age 80, more than half of all Americans will either have a cataract or have had cataract surgery.

The risk of developing a cataract increases with age. Other possible risk factors include:

- Intense heat or long-term exposure to UV rays from the sun

- Certain diseases, such as diabetes

- Obesity

- High blood pressure

- Inflammation in the eye

- Hereditary influences

- Long-term steroid use

- Eye injuries

- Other eye diseases

- Smoking

Early symptoms of cataract may include cloudy or blurry vision. Lights may cause a glare, seem too dim or seem too bright. Patients may also find it difficult to read or drive, especially at night, or may have to change his or her eyeglass prescription often.

Unfortunately, there are no medications or other treatment options besides surgery to correct cataract. However, in the United States, cataract surgery has a 95 percent success rate, generally resulting with patient’s vision of 20/20 to 20/40. And, it is the most frequently performed surgery, often performed as an outpatient procedure.

“By getting a complete, dilated eye exam, your doctor can discuss with you the best strategy to protect your vision well into the future,” said Hugh R. Parry, president and CEO of Prevent Blindness America. “We encourage everyone, especially those ages 40 and older, to make their vision a priority by scheduling an eye appointment today.”

UV Protection Critical for Eye Health

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Posted on 30th May 2012 by Pacific ClearVision Institute in General

AOA’s annual American Eye-Q® survey shows only 47 percent of Americans say UV protection is most important factor when purchasing sunglasses

Summer is on its way, but most Americans don’t recognize the importance of ultraviolet (UV) protection for their eyes to prevent damage and visual impairment. In fact, according to the American Optometric Association’s (AOA) recent American Eye-Q® survey, only 47 percent of Americans said UV protection is the most important factor when purchasing sunglasses. Additionally, less than one-third (28 percent) of Americans indicated that wearing sunglasses and sunscreen should always go hand in hand.

“UV radiation cannot be seen or felt, making it especially dangerous as the damage done to the eyes from long-term exposure to UV rays cannot be repaired,” said Fraser Horn, O.D., a member of the AOA’s Sports Vision Council and Assistant Professor of Optometry, Pacific University College of Optometry. “Whether it’s a cloudy or sunny day, summer or winter, eyes, just like the skin, need to be protected from the sun’s UV rays in order to decrease the risk of diseases and disorders.”

Ongoing exposure to UV radiation can cause serious harm to the eyes and age them prematurely. Long-term effects include cataracts, cancer, age-related macular degeneration, and damage to the retina. If the eyes are exposed to excessive amounts of UV radiation over a short period of time, a “sunburn” called photokeratitis can occur. This condition may be painful and include symptoms such as red eyes, a foreign body sensation or gritty feeling in the eyes, extreme sensitivity to light and excessive tearing. Photokeratitis is usually temporary and rarely causes permanent damage.

Parents should be particularly avid in protecting children’s eyes from UV rays, with children receiving up to three times the annual sun exposure of adults. Children’s eyes are especially susceptible to UV-related damage because the crystalline lenses in their eyes are more transparent to UV than adults. Unlike the mature lens of an adult eye, a child’s lens filters out less UV rays so more radiation reaches the retina. According to the American Eye-Q® survey, only 17 percent of parents make sure their children are wearing sunglasses when they are wearing sunscreen.

A good rule of thumb is to wear sunglasses or contact lenses that offer appropriate UV protection, apply UV-blocking sunscreen around the eye area and wear a hat to help protect the eyes.

To provide adequate protection for the eyes, the AOA recommends sunglasses and protective contact lenses that:

- Block out 99 to 100 percent of both UV-A and UV-B radiation
- Screen out 75 to 90 percent of visible light

Additionally, sunglasses should be perfectly matched in color and free of distortion and imperfection and have lenses that are gray for proper color recognition. The best way to monitor eye health, maintain good vision, and keep up-to-date on the latest in UV protection is by scheduling yearly comprehensive eye exams with an eye doctor.

About the survey:
The sixth annual American Eye-Q® survey was created and commissioned in conjunction with Penn, Schoen & Berland Associates (PSB). From May 19 – 23, 2011, using an online methodology, PSB interviewed 1,000 Americans 18 years and older who embodied a nationally representative sample of U.S. general population. (Margin of error at 95 percent confidence level)

Most blindness caused by cataract is preventable

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Posted on 30th May 2012 by Pacific ClearVision Institute in Cataracts

We find ourselves at a loss for words when confronted with the fact that 650,000 out of a total of 750,000 people go blind each year, ought not to have gone blind since their cataract condition was curable. They lost their precious eyesight for want of finance and medical services. These were the subjects of discussion at a roundtable conference held recently where speakers drove home some unsavoury facts about the dismal condition of eye treatment services in the country.

Unpleasant as it may sound, the bulk of Bangladeshi people reside overwhelmingly in the rural areas are bereft of requisite medical facilities that cater to cataract treatment. The treatment of cataract which causes a clouding of the natural lenses in the eye resulting in impaired vision that ultimately leads to blindness. As stated earlier, this condition can be successfully treated through operation. As 90% of the medical specialists and paramedics involved in the treatment of this condition reside, not in the district towns and villages but in the major metropolitan cities, for a patient to receive appropriate and timely treatment, s/he must travel to one of the major cities. Given the nature of disease, the patient must be accompanied by at least one attendant. All this costs money — money most patients do not have. Given a choice between zero treatment due to lack of finance, the sad reality is that for nearly 9 out 10 patients, it results in blindness.

The time has surely come for those who have been fortunate enough to be successful in life to show compassion for their less than fortunate brethren. Thanks to advances in medical science and the nature of the disease itself, treatment of cataract is not expensive like cancer treatment. And it is not only the wealthy that can make a difference by extending a helping hand. Were financial and corporate institutions like banks and conglomerates to get involved in fundraising, there is little to suggest why 90% of patients who go blind today could not be with sight tomorrow.

Prosthetic Retina Offers Simple Solution for Restoring Sight

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Posted on 30th May 2012 by Pacific ClearVision Institute in Retina

A device which could restore sight to patients with one of the most common causes of blindness in the developed world is being developed in an international partnership.

Researchers from the University of Strathclyde and Stanford University in California are creating a prosthetic retina for patients of age related macular degeneration (AMD), which affects one in 500 patients aged between 55 and 64 and one in eight aged over 85.

The device would be simpler in design and operation than existing models. It acts by electrically stimulating neurons in the retina, which are left relatively unscathed by the effects of AMD while other ‘image capturing’ cells, known as photoreceptors, are lost.

It would use video goggles to deliver energy and images directly to the eye and be operated remotely via pulsed near infra-red light- unlike most prosthetic retinas, which are powered through coils that require complex surgery to be implanted.

The prosthetic retina is a thin silicon device that converts pulsed near infra-red light to electrical current that stimulates the retina and elicits visual perception. It requires no wires and would make surgical implantation simpler.

The device has been shown to produce encouraging responses in initial lab tests and is reported in an article published in Nature Photonics. The technology is now being developed further.

Dr Keith Mathieson, now a Reader in the Institute of Photonics at the University of Strathclyde in Glasgow, was one of the lead researchers and first author of the paper. He said: “AMD is a huge medical challenge and, with an aging population, is continuing to grow. This means that innovative, practical solutions are essential if sight is to be restored to people around the world with the condition.

“The prosthetic retina we are developing has been partly inspired by cochlear implants for the ear but with a camera instead of a microphone and, where many cochlear implants have a few channels, we are designing the retina to deal with millions of light sensitive nerve cells and sensory outputs.

“The implant is thin and wireless and so is easier to implant. Since it receives information on the visual scene through an infra-red beam projected through the eye, the device can take advantage of natural eye movements that play a crucial role in visual processing.”

The research was co-authored by Dr. Jim Loudin of Stanford and led by Professor Daniel Palanker, also of Stanford, and Professor Alexander Sher, of the University of California, Santa Cruz.

Professor Palanker said: “The current implants are very bulky, and the surgery to place the intraocular wiring for receiving, processing and power is difficult. With our device, the surgeon needs only to create a small pocket beneath the retina and then slip the photovoltaic cells inside it.”

Dr Mathieson was supported through a fellowship from SU2P, a venture between academic institutions in Scotland and California aimed at extracting economic impact from their joint research portfolio in photonics and related technologies.

Strathclyde leads the collaboration, which also includes Stanford, the Universities of St Andrews, Heriot-Watt and Glasgow and the California Institute of Technology. SU2P was established through funding from Research Councils UK- as part of its Science Bridges awards- the Scottish Funding Council and Scottish Enterprise.

The research links to Photonics and Health Technologies at Strathclyde- two of the principal themes of the University’s Technology and Innovation Centre (TIC), a world-leading research and technology centre transforming the way universities, business, and industry collaborate.

Through Health Technologies at Strathclyde, academics work with industry and the health sector to find technologies for earlier, more accurate disease detection and better treatments, as well as life-long disease prevention.

Tiny Solar-Panel-Like Cells Help Restore Sight to the Blind

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Posted on 30th May 2012 by Pacific ClearVision Institute in Retina

Using tiny solar-panel-like cells surgically placed underneath the retina, scientists at the Stanford University School of Medicine have devised a system that may someday restore sight to people who have lost vision because of certain types of degenerative eye diseases.

This device — a new type of retinal prosthesis — involves a specially designed pair of goggles, which are equipped with a miniature camera and a pocket PC that is designed to process the visual data stream. The resulting images would be displayed on a liquid crystal microdisplay embedded in the goggles, similar to what’s used in video goggles for gaming. Unlike the regular video goggles, though, the images would be beamed from the LCD using laser pulses of near-infrared light to a photovoltaic silicon chip — one-third as thin as a strand of hair — implanted beneath the retina.

Electric currents from the photodiodes on the chip would then trigger signals in the retina, which then flow to the brain, enabling a patient to regain vision.

A study, to be published online May 13 in Nature Photonics, discusses how scientists tested the photovoltaic stimulation using the prosthetic device’s diode arrays in rat retinas in vitro and how they elicited electric responses, which are widely accepted indicators of visual activity, from retinal cells . The scientists are now testing the system in live rats, taking both physiological and behavioral measurements, and are hoping to find a sponsor to support tests in humans.

“It works like the solar panels on your roof, converting light into electric current,” said Daniel Palanker, PhD, associate professor of ophthalmology and one of the paper’s senior authors. “But instead of the current flowing to your refrigerator, it flows into your retina.” Palanker is also a member of the Hansen Experimental Physics Laboratory at Stanford and of the interdisciplinary Stanford research program, Bio-X. The study’s other senior author is Alexander Sher, PhD, of the Santa Cruz Institute of Particle Physics at UC Santa Cruz; its co-first authors are Keith Mathieson, PhD, a visiting scholar in Palanker’s lab, and James Loudin, PhD, a postdoctoral scholar. Palanker and Loudin jointly conceived and designed the prosthesis system and the photovoltaic arrays.

There are several other retinal prostheses being developed, and at least two of them are in clinical trials. A device made by the Los Angeles-based company Second Sight was approved in April for use in Europe, and another prosthesis-maker, a German company called Retina Implant AG, announced earlier this month results from its clinical testing in Europe.

Unlike these other devices — which require coils, cables or antennas inside the eye to deliver power and information to the retinal implant — the Stanford device uses near-infrared light to transmit images, thereby avoiding any need for wires and cables, and making the device thin and easily implantable.

“The current implants are very bulky, and the surgery to place the intraocular wiring for receiving, processing and power is difficult,” Palanker said. The device developed by his team, he noted, has virtually all of the hardware incorporated externally into the goggles. “The surgeon needs only to create a small pocket beneath the retina and then slip the photovoltaic cells inside it.” What’s more, one can tile these photovoltaic cells in larger numbers inside the eye to provide a wider field of view than the other systems can offer, he added.

Stanford University holds patents on two technologies used in the system, and Palanker and colleagues would receive royalties from the licensing of these patents.

The proposed prosthesis is intended to help people suffering from retinal degenerative diseases, such as age-related macular degeneration and retinitis pigmentosa. The former is the foremost cause of vision loss in North America, and the latter causes an estimated 1.5 million people worldwide to lose sight, according to the nonprofit group Foundation Fighting Blindness. In these diseases, the retina’s photoreceptor cells slowly degenerate, ultimately leading to blindness. But the inner retinal neurons that normally transmit signals from the photoreceptors to the brain are largely unscathed. Retinal prostheses are based on the idea that there are other ways to stimulate those neurons.

The Stanford device uses near-infrared light, which has longer wavelength than normal visible light. It’s necessary to use such an approach because people blinded by retinal degenerative diseases still have photoreceptor cells, which continue to be sensitive to visible light. “To make this work, we have to deliver a lot more light than normal vision would require,” said Palanker. “And if we used visible light, it would be painfully bright.” Near-infrared light isn’t visible to the naked eye, though it is “visible” to the diodes that are implanted as part of this prosthetic system, he said.

Palanker explained what he’s done by comparing the eye to camera, in which the retina is the film or the digital chip, and each photoreceptor is a pixel. “In our model we replace those photoreceptors with photosensitive diodes,” he said. “Every pixel is like a little solar cell; you send light, then you get current and that current stimulates neurons in the inner nuclear layer of the retina.” That, in turn, should have a cascade effect, activating the ganglion cells on the outer layer of the retina, which send the visual information to the brain that allows us to see.

For this study, Palanker and his team fabricated a chip about the size of a pencil point that contains hundreds of these light-sensitive diodes. To test how these chips responded, the researchers used retinas from both normal rats and blind rats that serve as models of retinal degenerative disease. The scientists placed an array of photodiodes beneath the retinas and placed a multi-electrode array above the layer of ganglion cells to gauge their activity. The scientists then sent pulses of light, both visible and near-infrared, to produce electric current in the photodiodes and measured the response in the outer layer of the retinas.

In the normal rats, the ganglions were stimulated, as expected, by the normal visible light, but they also presented a similar response to the near-infrared light: That’s confirmation that the diodes were triggering neural activity.

In the degenerative rat retinas, the normal light elicited little response, but the near-infrared light prompted strong spikes in activity roughly similar to what occurred in the normal rat retinas. “They didn’t respond to normal light, but they did to infrared,” said Palanker. “This way the sight is restored with our system.” He noted that the degenerated rat retinas required greater amounts of near-infrared light to achieve the same level of activity as the normal rat retinas.

While there was concern that exposure to such doses of near-infrared light could cause the tissue to heat up, the study found that the irradiation was still one-hundredth of the established ocular safety limit.

Since completing the study, Palanker and his colleagues have implanted the photodiodes in rats’ eyes and been observing and measuring their effect for the last six months. He said preliminary data indicates that the visual signals are reaching the brain in normal and in blind rats, though the study is still under way.

While this and other devices could help people to regain some sight, the current technologies do not allow people to see color, and the resulting vision is far from normal, Palanker said.

Future Treatment for Nearsightedness — Compact Fluorescent Light Bulbs?

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Posted on 30th May 2012 by Pacific ClearVision Institute in Retina

Researchers at the University of Alabama at Birmingham hope to one day use fluorescent light bulbs to slow nearsightedness, which affects 40 percent of American adults and can cause blindness.

In an early step in that direction, results of a study found that small increases in daily artificial light slowed the development of nearsightedness by 40 percent in tree shrews, which are close relatives of primates.

The team, led by Thomas Norton, Ph.D., professor in the UAB Department of Vision Sciences, presented the study results May 8 at the 2012 Association for Research in Vision and Ophthalmology annual meeting in Ft. Lauderdale.

People can see clearly because the front part of the eye bends light and focuses it on the retina in back. Nearsightedness, also called myopia, occurs when the physical length of the eye is too long, causing light to focus in front of the retina and blurring images.

Myopia has many causes, some related to inheritance and some to the environment. Research in recent years had, for instance, suggested that children who spent more time outdoors, presumably in brighter outdoor light, had less myopia as young adults. That raised the question of whether artificial light, like sunlight, could help reduce myopia development, without the risks of prolonged sun exposure, such as skin cancer and cataracts.

“Our hope is to develop programs that reduce the rate of myopia using energy efficient, fluorescent lights for a few hours each day in homes or classrooms,” said John Siegwart, Ph.D., research assistant professor in UAB Vision Sciences and co-author of the study. “Trying to prevent myopia by fixing defective genes through gene therapy or using a drug is a multi-year, multimillion-dollar effort with no guarantee of success. We hope to make a difference just with light bulbs.”

Sorting through theories

Work over 25 years had shown that putting a goggle over one eye of a study animal, one that lets in light but blurs images, causes the eye to grow too long, which in turn causes myopia. Other past studies had shown that elevated light levels could reduce myopia under these conditions, whether the light was produced by halogen lamps, metal halide bulbs or daylight. The current study is the first to show that the development of myopia can be slowed by increasing daily fluorescent light levels.

One prevailing theory on myopia-related shape changes in the eye is that they are caused by the blurriness of images experienced while reading or doing other near-work chores. Another holds some people develop myopia because they have low levels of vitamin D, which goes up with exposure to sunlight and could explain the connection between outdoor light and reduced myopia. A third theory, one reinforced by the current results, is that bright light causes an increase in levels of dopamine, a signaling molecule in the retina.

To test the theories, the team used a goggle that lets in light but no images to produce myopia in one eye of each tree shrew. They found that a group exposed to elevated fluorescent light levels for eight hours per day developed 47 percent less myopia than a control group exposed to normal indoor lighting, even though the images were neither more nor less blurry. They also found that animals fed vitamin D supplements developed myopia just like ones without the supplement. Given these results, the team is now experimenting with light levels and treatment times to see if a short, bright light treatment could be effective. They have also begun studies looking at the effect of elevated light on retinal dopamine levels as it relates to the reduction of myopia.

“If we can find the best kind of light, treatment period and light level, we’ll have the scientific justification to begin studies raising light levels in schools, for instance,” said Norton. “Compact fluorescent bulbs use much less electricity than standard light bulbs, and future programs raising light levels will have more impact the less expensive they are.”

New Eye Imaging Techniques Are On the Horizon

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Posted on 30th May 2012 by Pacific ClearVision Institute in General

The same technology used by astronomers to obtain clear views of distant stars is now being used by optometrists to perform incredibly detailed examinations of the living eye.

An update on new developments in ocular imaging techniques — and how they may affect clinical vision care in the not-too-distant future — is presented in an article titled “Adaptive Optics Scanning Laser Ophthalmoscope-based Microperimetry” published in a special May issue of Optometry and Vision Science, official journal of the American Academy of Optometry.

Cutting-edge techniques now allow researchers to visualize the fine structure of the eye in a way that was “not conceivable 20 years ago,” according to a guest editorial by Scott Read OD PhD FAAO (Candidate) and colleagues. “As these advanced imaging methods continue to develop, the potential for imaging ocular structures down to the cellular level in everyday clinical practice has become a reality — and the potential to improve patient care is truly stunning,” Dr Read and coauthors add.

New Techniques Provide Cellular-Level Images of the Living Eye The special issue presents 30 reports on the latest, most advanced techniques for imaging and measurement of various eye structures: the retina and optic nerve, lens and ciliary body, and the anterior eye. Written by leading researchers and clinicians, the contributions provide a fascinating look at these remarkable new technologies, with a glimpse of their likely extensions into clinical practice.

As just one example, William S. Tuten, OD, MS, and colleagues of the University of California, Berkeley, report on the development and use of an “adaptive optics scanning laser ophthalmoscope.” Adaptive optics refers to the use of advanced techniques to correct for optical aberrations through any transparent media. Originally developed for use in telescopes to correct for the distorting effects of the atmosphere, adaptive optics is now being applied to evaluating the structure and function of the human eye.

Dr. Tuten and colleagues have applied adaptive optics to perimetry — also known as visual field testing — on the microscopic scale. Perimetry is an important part of evaluation for patients with vision disorders including macular degeneration, retinitis pigmentosa, and diabetic retinopathy. Perimetry measures vision in all parts of the visual field, including the peripheral vision.

Promising Applications to Improve Clinical Vision Care The new paper describes (and illustrates) the use of adaptive optics-guided microperimtery to assess visual fields at an unprecedented level of detail. The technique can not only show limitations in visual fields, but can trace the defect to individual retinal photoreceptor cells. High-speed tracking is used to correct for normal eye movement, or “jitter,” that is practically undetectable using conventional imaging techniques.

In addition, by using microscopic blood vessels as anatomical landmarks, the adaptive optics technique permits repeated studies to be repeated over time at a high level of precision. This offers unique opportunities for studying how treatments work on the cellular level, as well as following the effects of treatment over time in individual patients.

“This technique opens new horizons for clinician-scientists, and later clinicians, to better understand, and plot out, the relationships between vision and the retinal photoreceptors at a microscopic level,” comments Anthony Adams, OD, PhD, Editor-in-Chief of Optometry and Vision Science. “It enables a new understanding of vision loss in patients with retinal disorders where there are discrete photoreceptor losses — for example, macular degeneration.”

Adaptive optics-guided microperimetery and other advanced imaging technologies described in the special issue have the potential to revolutionize the management of eye diseases, Dr. Read and colleagues believe. They conclude, “With ongoing improvements in imaging speed and resolution, and with the application of innovative methods to improve the clinical usefulness of ocular imaging techniques, the future of ocular imaging is bright!”