Non-invasive Technique to Correct Vision

New study has developed a novel non-invasive approach to permanently correct vision. The technique was developed by Columbia Engineering researcher Sinisa Vukelic and shows great promise in preclinical models. The new technique uses an ultrafast laser to alter the biochemical and biomechanical properties of corneal tissue. This non-invasive approach claims to have fewer side effects than most refractive surgeries. The study is published in Nature Photonics.

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Myopia and its correction

Myopia, also referred to as near-sightedness or short-sightedness is a condition of the eye where light focuses in front of, instead of on, the retina. This results in distant objects to appear blurry while close objects appear normal. Myopia is a common condition in today’s world and is on a constant rise. Twice as many people in the US and Europe are affected with myopia than 50 years ago. Seventy to ninety percent of teenagers and young adults in East Asia are near-sighted. Estimates suggest that about 2.5 billion of people across the globe may be affected by myopia by 2020.

The corrective measures for myopia include eye glasses, contact lenses and if you’re looking for a permanent correction, a corneal refractive surgery. However, while vision correction surgery has high success rates, it is an invasive procedure. The surgery is also subject to post-surgical complications, and in rare cases permanent vision loss. Moreover, some laser-assisted vision correction surgeries may also thin and in some cases weaken the cornea.

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A new promising alternative

A new non-invasive and non-surgical technique promises to overcome the above short-comings. The new method uses a femtosecond oscillator, an ultrafast laser that delivers pulses of very low energy at high repetition rate. These laser pulses selectively alters localized biochemical and biomechanical properties of corneal tissue. The technique has the ability to change the tissue's macroscopic geometry.

Overall the technique has fewer side effects and limitations than those seen in refractive surgeries. For example, the technique can also be used in patients with thin corneas, dry eyes, and other abnormalities who cannot undergo refractive surgery.

The new vision corrective technique could lead to treatment for myopia, hyperopia, astigmatism, and irregular astigmatism.

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Mechanism of action

An ultra-fast laser is used to alter biochemical and biomechanical properties of collagenous tissue without causing cellular damage and tissue disruption.

"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.

"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 the new approach is that the induction of low-density plasma causes ionization of water molecules within the cornea. Ionization creates a reactive oxygen species which interacts with the collagen fibrils to form chemical bonds, or crosslinks. Selective introduction of these crosslinks in the targeted corneal tissue induces changes in the mechanical properties of the tissue.

The crosslinking alters the collagen properties in the treated corneal regions and changes the overall macrostructure of the cornea. The treatment only ionizes the target molecules within the cornea and avoids the optical breakdown of the corneal tissue.

"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. "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."

References:

1. Chao Wang, Mikhail Fomovsky, Guanxiong Miao, Mariya Zyablitskaya, Sinisa Vukelic, "Femtosecond laser crosslinking of the cornea for non-invasive vision correction" Nature Photonics (2018) doi:10.1038/s41566-018-0174-8
2. Cornea - (https://en.wikipedia.org/wiki/Cornea)

Source-Medindia