Millions of Americans experience various vision issues, from slight blurriness to complete blindness. Yet, not everyone is keen on wearing prescription glasses or contact lenses. As a result, many people opt for corrective eye surgeries each year, including LASIK, which utilizes a laser to reshape the cornea and improve vision. However, this procedure can lead to negative side effects, prompting researchers to explore a method to reshape the cornea without cutting it, based on initial tests with animal tissue.
Michael Hill, a chemistry professor at Occidental College, is set to share his team’s findings at the fall meeting of the American Chemical Society (ACS) from August 17-21. This event will showcase around 9,000 presentations across various scientific fields.
The cornea, which sits at the front of the eye, has a dome shape that helps it bend light and focus it on the retina. If the cornea is not shaped correctly, it can lead to blurry vision. LASIK uses lasers to cut precise portions of the cornea to reshape it. While it’s considered a safe procedure, it comes with risks and can compromise the eye’s structural integrity. Hill notes, “LASIK is just a modern twist on traditional surgery. It still involves removing tissue—just in a fancier way.”
But what if you could reshape the cornea without making any cuts?
This is the question Hill and his collaborator Brian Wong are investigating through a technique called electromechanical reshaping (EMR). Wong, a professor and surgeon at the University of California, Irvine, explains, “We stumbled upon this whole process of chemical modification while examining living tissues as moldable materials.”
The human body contains many collagen-rich tissues, including the cornea, which are held in their shapes by attractions between oppositely charged components. Since these tissues are primarily water, applying an electric charge can decrease the tissue’s pH, making it more acidic. By adjusting the pH, the rigid attractions loosen, allowing the tissue to become malleable. Once the pH returns to normal, the tissue retains its new shape.
The researchers have previously used EMR to reshape rabbit ears with high cartilage content and to change skin and scars in pigs. However, the cornea was a critical tissue they were eager to investigate.
In their recent studies, the team created specialized platinum “contact lenses” that served as a template for reshaping the cornea, placing them over rabbit eyes submerged in a saline solution to mimic natural tears. The platinum acted as an electrode, causing pH changes when a small electric potential was applied. Remarkably, the cornea adjusted its curvature to match the lens shape within about a minute—similar in time to LASIK but with fewer steps, lower costs, and no incisions.
In trials involving 12 rabbit eyes, 10 of which were treated to mimic nearsightedness, the procedure successfully enhanced the focusing power of the eye, improving vision. Importantly, the cells survived the treatment due to careful pH control. The researchers also indicated that their method might potentially reverse cloudiness in the cornea, a condition currently treatable only through complete transplants.
Although this initial work shows promise, the researchers caution that it is still in its infancy. Wong describes the next steps as “the long march through detailed animal studies,” which will include tests on living rabbits rather than just their eyes. They also aim to explore the types of vision corrections EMR could achieve for conditions like nearsightedness, farsightedness, and astigmatism. However, uncertainties in funding have temporarily stalled the project. “There’s a long way to go before we can make this clinical. Yet, if we succeed, this method could be more affordable, widely applicable, and even reversible,” Hill concludes.
Title Electrochemical corneal refraction
Abstract The cornea plays a crucial role in the eye’s refractive power, comprising about two-thirds of it. The stroma of the cornea consists of stacked collagen fibrils, which help eliminate backscattered light and maintain its shape. Various factors like anatomical variation and trauma can alter the cornea’s structure and transparency, impacting vision. Surgical options to address conditions such as myopia and astigmatism include LASIK and PRK, but these procedures are costly and can permanently weaken the cornea. This report discusses the application of electromechanical reshaping (EMR) as a non-invasive alternative to laser vision correction, utilizing ex vivo rabbit eyes. EMR leverages short electrochemical pulses to change interstitial water and diffuses protons into collagenous tissues. The process disrupts the ionic bonds, making the tissue temporarily moldable. Once the pH returns to normal, the cornea maintains its new shape. Techniques like optical coherence tomography and confocal microscopy indicate that EMR allows for controlled corneal shaping while preserving the collagen structure and cell viability.
This research was supported by the National Eye Institute of the National Institutes of Health and the John Stauffer Charitable Trust.
