Noninvasive technique to correct vision


Engineers have developed a noninvasive approach to permanently correct vision that shows great promise in preclinical models. The method uses a femtosecond oscillator for selective and localized alteration of the biochemical and biomechanical properties of corneal tissue. The technique, which changes the tissue’s macroscopic geometry, is non-surgical and has fewer side effects and limitations than those seen in refractive surgeries. The study could lead to treatment for myopia, hyperopia, astigmatism, and irregular astigmatism.

Corneal topography before and after the treatment, paired with virtual vision that simulates effects of induced refractive power change.
 

Nearsightedness, or myopia, is an increasing problem around the world. There are now twice as many people in the US and Europe with this condition as there were 50 years ago. In East Asia, 70 to 90 percent of teenagers and young adults are nearsighted. By some estimates, about 2.5 billion of people across the globe may be affected by myopia by 2020.

Eye glasses and contact lenses are simple solutions; a more permanent one is corneal refractive surgery. But, while vision correction surgery has a relatively high success rate, it is an invasive procedure, subject to post-surgical complications, and in rare cases permanent vision loss. In addition, laser-assisted vision correction surgeries such as laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) still use ablative technology, which can thin and in some cases weaken the cornea.

Columbia Engineering researcher Sinisa Vukelic has developed a new non-invasive approach to permanently correct vision that shows great promise in preclinical models. His method uses a femtosecond oscillator, an ultrafast laser that delivers pulses of very low energy at high repetition rate, for selective and localized alteration of the biochemical and biomechanical properties of corneal tissue. The technique, which changes the tissue’s macroscopic geometry, is non-surgical and has fewer side effects and limitations than those seen in refractive surgeries. For instance, patients with thin corneas, dry eyes, and other abnormalities cannot undergo refractive surgery. The study, which could lead to treatment for myopia, hyperopia, astigmatism, and irregular astigmatism, was published May 14 in Nature Photonics.

“We think our study is the first to use this laser output regimen for noninvasive change of corneal curvature or treatment of other clinical problems,” says Vukelic, who is a lecturer in discipline in the department of mechanical engineering. His method uses a femtosecond oscillator to alter biochemical and biomechanical properties of collagenous tissue without causing cellular damage and tissue disruption. The technique allows for enough power to induce a low-density plasma within the set focal volume but does not convey enough energy to cause damage to the tissue within the treatment region.

“We’ve seen low-density plasma in multi-photo imaging where it’s been considered an undesired side-effect,” Vukelic says. “We were able to transform this side-effect into a viable treatment for enhancing the mechanical properties of collagenous tissues.”

The critical component to Vukelic’s approach is that the induction of low-density plasma causes ionization of water molecules within the cornea. This ionization creates a reactive oxygen species, (a type of unstable molecule that contains oxygen and that easily reacts with other molecules in a cell), which in turn interacts with the collagen fibrils to form chemical bonds, or crosslinks. The selective introduction of these crosslinks induces changes in the mechanical properties of the treated corneal tissue.

When his technique is applied to corneal tissue, the crosslinking alters the collagen properties in the treated regions, and this ultimately results in changes in the overall macrostructure of the cornea. The treatment ionizes the target molecules within the cornea while avoiding optical breakdown of the corneal tissue. Because the process is photochemical, it does not disrupt tissue and the induced changes remain stable.

“If we carefully tailor these changes, we can adjust the corneal curvature and thus change the refractive power of the eye,” says Vukelic. “This is a fundamental departure from the mainstream ultrafast laser treatment that is currently applied in both research and clinical settings and relies on the optical breakdown of the target materials and subsequent cavitation bubble formation.”

“Refractive surgery has been around for many years, and although it is a mature technology, the field has been searching for a viable, less invasive alternative for a long time,” says Leejee H. Suh, Miranda Wong Tang Associate Professor of Ophthalmology at the Columbia University Medical Center, who was not involved with the study. “Vukelic’s next-generation modality shows great promise. This could be a major advance in treating a much larger global population and address the myopia pandemic.”

Vukelic’s group is currently building a clinical prototype and plans to start clinical trials by the end of the year. He is also looking to develop a way to predict corneal behavior as a function of laser irradiation, how the cornea might deform if a small circle or an ellipse, for example, were treated. If researchers know how the cornea will behave, they will be able to personalize the treatment — they could scan a patient’s cornea and then use Vukelic’s algorithm to make patient-specific changes to improve his/her vision.

“What’s especially exciting is that our technique is not limited to ocular media — it can be used on other collagen-rich tissues,” Vukelic adds. “We’ve also been working with Professor Gerard Ateshian’s lab to treat early osteoarthritis, and the preliminary results are very, very encouraging. We think our non-invasive approach has the potential to open avenues to treat or repair collagenous tissue without causing tissue damage.”

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Materials provided by Columbia University School of Engineering and Applied Science.

Lasers might be the cure for brain diseases such as Alzheimer’s and Parkinson’s.


Researchers at Chalmers University of Technology in Sweden, together with researchers at the Polish Wroclaw University of Technology, have made a discovery that may lead to the curing of diseases such as Alzheimer’s, Parkinson’s and Creutzfeldt-Jakob disease (the so called mad cow disease) through photo therapy.

The researchers discovered, as they show in the journal Nature Photonics, that it is possible to distinguish aggregations of the proteins, believed to cause the diseases, from the the well-functioning proteins in the body by using multi-photon .

“Nobody has talked about using only light to treat these diseases until now. This is a totally new approach and we believe that this might become a breakthrough in the research of diseases such as Alzheimer’s, Parkinson’s and Creutzfeldt-Jakob disease. We have found a totally new way of discovering these structures using just laser light“, says Piotr Hanczyc at Chalmers University of Technology.

If the aggregates are removed, the disease is in principle cured. The problem until now has been to detect and remove the aggregates.
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The researchers now harbor high hopes that photo acoustic therapy, which is already used for tomography, may be used to remove the malfunctioning proteins. Today amyloid are treated with chemicals, both for detection as well as removal. These chemicals are highly toxic and harmful for those treated.

With multi photon laser the chemical treatment would be unnecessary. Nor would surgery be necessary for removing of aggregates. Due to this discovery it might, thus, be possible to remove the harmful protein without touching the surrounding tissue.

These diseases arise when amyloid beta protein are aggregated in large doses so they start to inhibit proper cellular processes.

Different proteins create different kinds of amyloids, but they generally have the same structure. This makes them different from the well-functioning proteins in the body, which can now be shown by multi photon technique.

‘Star Trek’ Prototype Tractor Beam Developed By Scientists.


 

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It may still be a few years away from practical use, but scientists have created a real tractor beam, like the ones featured in the “Star TrekTV series and movies.

Simply put, this technology utilizes a beam of light to attract objects, according to theUniversity of St. Andrews in Scotland. In “Star Trek,” tractor beams were often used to pull spaceships and other objects closer to the focal point of the light source attached to another ship.

Researchers at St. Andrews and the Institute of Scientific Instruments, or ISI, in the Czech Republic have figured out a way of generating an optical field that can reverse the radiation pressure of light.

German astronomer Johannes Kepler noticed in 1619 that comet tails point away from the sun, a radiation force that the St. Andrews and ISI team hoped to reverse.

According to the BBC, Pavel Zemanek of ISI said, “The whole team have spent a number of years investigating various configurations of particles delivery by light. I am proud our results were recognised in this very competitive environment and I am looking forward to new experiments and applications. It is a very exciting time.”

So far, based on their research findings published in Nature Photonics, the team is able to move tiny particles, on a microscopic level.

Team leader Tomas Cizmar, of the St. Andrews School of Medicine, said the new technology has great potential.

“The practical applications could be very great, very exciting,” Cizmar told the BBC. “The tractor beam is very selective in the properties of the particles it acts on, so you could pick up specific particles in a mixture. Eventually, this could be used to separate white blood cells, for example.”

While the researchers hope this tractor beam technology will be useful in the medical field, they don’t anticipate it can ever be used to capture and haul large objects like spaceships.

“Unfortunately, there is a transfer of energy. On a microscopic scale, that is OK, but on a macro scale, it would cause huge problems,” said Cizmar.

“It would result in a massive amount of heating of an object, like a space shuttle. So trapping a spaceship is out of the question.”

Tractor beam concepts have been experimented with before.

In 2011, a NASA-funded study examined how special laser beams might be used to capture and gather sample materials on unmanned, robotic space missions,Space.com reported.

“Though a mainstay in science fiction, and ‘Star Trek’ in particular, laser-based trapping isn’t fanciful or beyond current technological know-how,” Paul Stysley of NASA’s Goddard Space Flight Center said at the time.

And in 2012, New York University physicists David Ruffner and David Grier developed a way to use special lasers, called Bessel beams, to direct light in concentric circles at an object — albeit a 1.5-micrometer silica sphere — and the beams could then reconstruct themselves on opposite sides of the sphere, making it possible to pull the object back to the source of the beams.

The only problem with this theory is that, like the current tests by the scientists at St. Andrews and ISI, applying these techniques to move very large objects isn’t practical yet — the huge energy requirements to make it work would destroy the objects trying to be pulled.

Source: http://www.huffingtonpost.com

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