Millions of people around the world are inflicted with vision disorders, including refractive errors such as near-sightedness (myopia), far-sightedness (hyperopia), and blurry sightedness (astigmatism), that can lead to eye conditions ranging from blurriness to blindness.
Many of the common eye concerns can be addressed by corrective lenses (eye-glasses or contact lenses). But not everyone wants to wear prescription glasses or contact lenses, and many people now opt to undergo corrective eye surgery (refractive surgery).
Human corneas are dome-shaped, clear structures that sit at the front of the eye, bending (refracting) light signals from surroundings and focusing it onto the retina, from where it is sent to the brain which interprets it as an image. Corneas are responsible for nearly two-thirds of the refractive power of the eye.
But if the cornea is either too long, too short, or misshapen,the light signal is not refracted (bent) properly onto the retina, resulting in a blurry image. Anatomical variation in cornea shape, birth defects, trauma, and various pathologies can alter the shape, structural stability, and transparency of the cornea, thus affecting vision.
Surgical interventions to treat myopia, hyperopia, and astigmatism include laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). In LASIK or PRK procedures, specialized lasers reshape the cornea by removing precise sections of the eye tissue, and realigning the cornea so light signals focus onto the retina.
LASIK and PRK are both common procedures and are considered safe, but despite their popularity, these procedures are expensive and permanently lower the biomechanical strength of the cornea.Researchers at Occidental College in the United States, now say they have found a way to remodel the cornea chemically, rather than use a laser, and refocus light on the retina, through a process known as electromechanical reshaping (EMR).
In the body, the shapes of many collagen-containing tissues, including corneas, are held in place by attractions of oppositely charged components. These tissues contain a lot of water, so applying an electric potential to them lowers the tissue’s pH, making it more acidic. By altering the pH, the rigid attractions within the tissue are loosened and make the shape malleable. When the original pH is restored, the tissue is locked into the new shape.
Previously, the researchers used EMR to reshape cartilage-rich rabbit ears, as well as alter scars and skin in pigs. But one collagen-rich tissue that they were eager to explore was the cornea. For their work, the team constructed specialized, platinum ‘contact lenses’ that provided a template for the corrected shape of the cornea, and then placed each over a rabbit eyeball in a saline solution meant to mimic natural tears. The platinum lens acted as an electrode to generate a precise pH change when the researchers applied a small electric potential to the lens.
After about a minute, which is around the same amount of time LASIK takes, the cornea’s curvature conformed to the shape of the platinum lens. Compared to LASIK, the new procedure involves fewer steps, uses less expensive equipment and needs no incisions on the cornea. They repeated this setup on 12 separate rabbit eyeballs, 10 of which were treated as if they had myopia. In all the ‘myopic’ eyeballs, the treatment dialed in the targeted focusing power of the eye, which would correspond to improved vision.
The cells in the eyeball survived the treatment, as the researchers carefully controlled the pH gradient. Additionally, in other experiments, the team demonstrated that their technique might be able to reverse some chemical-caused cloudiness to the cornea—a condition that is currently only treatable through a complete corneal transplant. Though this initial work is promising, the researchers admitted that there is still a long road between what they have achieved now and reaching clinical trials on humans. But they emphasized that their technique has the potential to become widely applicable, vastly cheaper, and even reversible,
