Safer, cheaper vision correction

 Vision correction without lasers or surgery, An alternative to LASIK 

Millions of Americans have altered vision, ranging from blurriness to blindness. But not everyone wants to wear prescription glasses or contact lenses. Accordingly, hundreds of thousands of people undergo corrective eye surgery each year, including LASIK, a laser-assisted surgery which reshapes the cornea and corrects vision. The procedure can result in negative side effects, prompting researchers to take the laser out of LASIK by remodeling the cornea, rather than cutting it, in initial animal tissue tests. Researchers are developing a futuristic alternative to LASIK which reshapes the eye without lasers or incisions. Using mild electrical pulses and platinum contact lenses, they temporarily soften the cornea so it can be molded into a new shape. Early tests on rabbit eyes successfully corrected nearsightedness in about a minute while preserving the eye’s structure.

Hundreds of thousands of people undergo corrective laser-based eye surgeries each year, but researchers are hoping to change that thanks to a corneal reshaping technique currently in development. Human corneas are dome-shaped, clear structures that sit at the front of the eye, bending light from surroundings and focusing it onto the retina, where it’s sent to the brain and interpreted as an image. But if the cornea is misshapen, it doesn’t focus light properly, resulting in a blurry image. With LASIK, specialized lasers reshape the cornea by removing precise sections of the tissue. This common procedure is considered safe, but it has some limitations and risks, and cutting the cornea compromises the structural integrity of the eye. Millions around the world live with blurry vision, nearsightedness or more severe sight problems. While glasses and contact lenses help many people, millions have turned to corrective procedures such as LASIK to sharpen their eyesight. But scientists are now exploring a very different approach which could someday reshape the eye without lasers, cutting or invasive surgery.

Researchers from Occidental College and the University of California, Irvine have been developing an experimental technique called electromechanical reshaping (EMR). Instead of carving away tissue like LASIK, the method temporarily softens the cornea so it can be gently molded into a new shape. Early tests in rabbit eyes suggest the technology may one day provide a cheaper, less invasive alternative to traditional laser eye surgery. The idea behind EMR emerged unexpectedly during earlier experiments involving cartilage and other collagen-rich tissues. "The whole effect was discovered by accident," explains Brian Wong, a professor and surgeon at the University of California, Irvine. "I was looking at living tissues as moldable materials and discovered this whole process of chemical modification." Collagen-rich tissues throughout the body, including the cornea, maintain their shape through networks of charged molecules which hold the structure together. Because these tissues contain large amounts of water, scientists found that applying a mild electric current can temporarily alter the tissue's acidity level, or pH. As the pH shifts, the molecular bonds holding the tissue rigid begin to loosen. This briefly makes the tissue flexible enough to reshape. Once the pH returns to normal, the tissue stiffens again and locks into its new form. Researchers had previously tested EMR on rabbit ear cartilage, pig skin and scar tissue. The cornea became one of the most promising targets because even small changes in its curvature can dramatically improve vision.

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. The cornea is the clear, dome-shaped surface at the front of the eye. It bends incoming light and helps focus images onto the retina. When the cornea is too steep, too flat or unevenly shaped, vision becomes blurry. LASIK corrects those problems by using lasers to remove tiny amounts of corneal tissue and permanently reshape the eye. Although the procedure is widely used and generally considered safe, it can sometimes lead to complications including dry eyes, glare, halos and weakened corneal structure. Michael Hill, a chemistry professor at Occidental College, says the basic concept behind LASIK still comes down to tissue removal. "LASIK is just a fancy way of doing traditional surgery. It's still carving tissue -- it's just carving with a laser." This limitation inspired researchers to search for a way to reshape the cornea without making incisions at all.

In this work, the team constructed specialized, platinum “contact lenses” which provided a template for the corrected shape of the cornea, 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, the cornea’s curvature conformed to the shape of the lens, about the same amount of time LASIK takes, but with fewer steps, less expensive equipment and no incisions. The team tested the procedure on 12 rabbit eyeballs. Ten were treated to simulate correction for myopia, also known as nearsightedness. In those eyes, the corneas successfully achieved the intended focusing power which would correspond to improved vision. Importantly, the cells within the tissue remained alive because the researchers carefully controlled the pH changes during treatment.

The researchers also reported another intriguing possibility. In separate experiments, the same technique appeared capable of reversing some forms of chemical cloudiness in the cornea. Today, severe corneal clouding often requires a full corneal transplant. Scientists say EMR could potentially avoid some of the major drawbacks associated with LASIK and related procedures such as PRK. Because the method does not remove corneal tissue, it may preserve more of the eye's natural structural strength. The electromechanical reshaping technique successfully flattened rabbit cornea from its original shape to a corrected one. 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, because 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. Laboratory imaging studies using optical coherence tomography (OCT), confocal microscopy and second-harmonic generation microscopy also suggested that the cornea's collagen structure remained largely intact after treatment. Researchers reported no major loss of transparency or obvious tissue damage in the early experiments.

More recent reports and engineering updates have continued to refine the technology. Scientists are now developing advanced electrode contact lenses capable of monitoring corneal shape, hydration and transparency during treatment. Researchers have also explored whether EMR could eventually be adapted for conditions beyond nearsightedness, including farsightedness, astigmatism and certain reconstructive procedures involving cartilage-rich tissues. Some scientists believe the approach could ultimately become far less expensive than laser-based surgery because it may not require large, complex laser systems. Despite the excitement surrounding the technology, researchers caution that EMR remains highly experimental. This research was funded by the National Eye Institute of the National Institutes of Health and the John Stauffer Charitable Trust. Though this initial work is promising, the researchers emphasize that it is in its very early stages. Next up is the long march through animal studies that are detailed and precise including tests on a living rabbit rather than just its eyeball. They also plan to determine the types of vision correction possible with EMR, such as near- and far-sightedness and astigmatism. Though the next steps are planned, uncertainties in the team’s scientific funding have put them on hold. 

"There's a long road between what we've done and the clinic," concludes Hill. "But, if we get there, this technique is widely applicable, vastly cheaper and potentially even reversible." Researchers are also continuing to study how precisely the procedure can correct different types of vision problems and whether long-term side effects might emerge after treatment. For now, LASIK remains the standard option for surgical vision correction. But EMR has opened the door to a future where fixing blurry vision may no longer require lasers, cutting, or permanent tissue removal. The American Chemical Society (ACS) is a nonprofit organization founded in 1876. ACS is committed to improving all lives through the transforming power of chemistry. Its mission is to advance scientific knowledge, empower a global community and champion scientific integrity, and its vision is a world built on science. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. 

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Antarctica's 'Doomsday Glacier'

 "Doomsday Glacier" is on the brink of losing its ice shelf          

The Thwaites Glacier has the world’s widest glacial interface with the ocean, extending roughly 75 miles (120 km), and the collapse of this glacier could cause a catastrophic rise in sea levels worldwide. Some 30 miles (50 km) of the glacier’s ocean front terminates in an ice shelf which floats above Pine Island Bay. The grounding line of the ice shelf extends downward from the sea surface to depths between about 2,600 and 3,940 feet (roughly 800 and 1,200 meters). The glacier covers approximately 74,100 square miles (192,000 square km). West Antarctica's "Doomsday Glacier" is further compromising the already melting ice mass and threatening to unleash devastating sea-level rises. The Thwaites Glacier is nicknamed the "Doomsday Glacier" because its collapse would send so much ice into the Southern Ocean that global sea levels would rise by 2.1 feet (65 cm's or 26 inches), flooding coastal communities worldwide. This collapse could take centuries, but there is an imminent threat to Thwaites' eastern ice shelf, which will likely accelerate the glacier's demise.

Antarctica landmass is almost wholly covered by a vast ice sheet. Often described as a continent of superlatives, Antarctica is not only the world’s southernmost continent. It is also the world’s highest, driest, windiest, coldest and iciest continent. Antarctica is about 5.5 million square miles (14.2 million square km) in size, and thick ice covers about 98% of the land. The continent is divided into East Antarctica and West Antarctica. Researchers say that satellite images reveal that the Thwaites eastern ice shelf is about to detach from the glacier. While the glacier sits on land, the ice shelf is a floating body of ice which is attached to the glacier's mouth. Researchers still have a lot to learn about the glacier, but this shelf acts as a buttress, restraining the flow of ice from the glacier into the sea. The ice shelf is very likely to break up in the near future. The last bit of ice shelf in front of the glacier is poised to disintegrate as per researcher's. We don't know quite how this ice shelf is going to break up, but it's definitely going to go. 

The continental ice sheet contains approximately 7 million cubic miles (about 29 million cubic km) of ice, representing about 90% of the world’s ice and 80% of its fresh water. Its average thickness is about 5,900 feet (1,800 metres). Ice shelves, or ice sheets floating on the sea, cover many parts of the Ross and Weddell seas. These shelves together with other shelves around the continental margins, fringe about 45% of Antarctica. Around the Antarctic coast, shelves, glaciers, and ice sheets continually “calve,” or discharge, icebergs into the seas. The continent is a cold dry desert where access to water determines the abundance of life. While the terrestrial ecosystem contains more than a thousand known species of organisms, most of these are microorganisms. Maritime Antarctica supports more life than inland Antarctica, and the surrounding ocean is as rich in life as the land is barren. Around the size of Florida, Thwaites Glacier is the largest glacier in West Antarctica. The gigantic river of ice is more than 6,500 feet (2,000 meters) thick in some parts and 75 miles (120 km's) across. The glacier has been melting rapidly since the 1980s, losing hundreds of billions of tons of ice. It's due to relatively warm ocean water flowing underneath the ice shelf and melting the glacier at its base, where ice sits on ground that's below sea level. The glacier has retreated around 12.4 miles (20 km) since 1992.

Governments mandated many early expeditions, whether ostensibly economic, scientific or exploratory in character, to make territorial claims. The ice-choked and stormy seas around Antarctica long hindered exploration by wooden-hulled ships. No lands break the relentless force of the prevailing west winds as they race clockwise around the continent, dragging westerly ocean currents along beneath. The southernmost parts of the Atlantic, Pacific, and Indian oceans meet the Southern (or Antarctic) Ocean, the cold oceanic water mass with unique biological and physical characteristics. Icebreakers and aircraft now make access relatively easy, although still not without hazard in inclement conditions. In addition, many tourists have visited Antarctica, which has underscored the value of scenic resources in the continent’s economic development. Modeling the demise of massive glaciers is a complex task, making it hard to put an exact date on when Thwaites Glacier will finally collapse. However, a latest study found that the glacier could be losing 180 billion to 200 billion tons of ice/year by 2067. The Thwaites eastern ice shelf is fracturing where the shelf is held in place by a ridge on the ocean floor, and at the mouth of the glacier. Movement on the western side of the shelf, where the ice is breaking away, has approximately doubled over the last eight months.

As per new expeditions, each range in ever-increasing detail, concepts of the geologic structure are continually modified. Antarctica’s structural record is now known to be more complex than that implied in the past. The average thickness of the terrestrial crust for both East and West Antarctica approximates that of other continents. Although it has been postulated that West Antarctica might be an oceanic island archipelago if the ice were to melt, its crustal thickness of about 20 miles indicates an absence of oceanic structure. This thickness is similar to that of coastal parts of other continents. The crust thickens sharply along the Transantarctic Mountains front, possibly a deep crustal fault system, and averages about 25 miles thick in East Antarctica. Significant earthquakes are not recorded along this or other known faults in Antarctica, the most seismically quiet of all continents, in which mostly minor activity is associated with surrounding oceanic ridges or volcanoes. However, the occurrence of one unusually large earthquake of magnitude 6.4 in the Bellingshausen Sea in 1977 suggests that the Antarctic Plate may have greater seismicity than generally believed. Thwaites Glacier's slow collapse is part of a wider concern among scientists for the future of the West Antarctic ice sheet. 

Thwaites is a key pillar of the ice sheet, protecting other ice from slipping into the ocean. If the whole ice sheet were to go, sea levels would rise by 10.8 feet (3.3 m), according to the British Antarctic Survey. The collapse of ice sheets like this one are considered tipping points, or "points of no return," in the fight against climate change, meaning that once they are crossed, they bring about permanent changes which cannot be reversed for many thousands of years. "Much like other Antarctic sea ice, and the glacier itself, this shelf is undermined by warmer, saltier water being forced up from deep below the surface of the Southern Ocean. Larter noted that it's more about the circulation of water than warming, but indications are that human-driven climate change is ultimately to blame. There is an active scientific debate about exactly how this works, but it seems pretty clear that in some way, the changes to the Southern Hemisphere westerly winds are what is driving warm water onto the continent and wind changes are part of the wider pattern of climate change that we're seeing. The ancient crust of Antarctica must have been highly mobile and the configuration of the continent many hundreds of millions of years ago in the Precambrian far different from today’s situation. 

There are two faces of the present-day continent of Antarctica. One, seen visually, consists of the exposed rock and ice-surface terrain. The other, seen only indirectly by seismic or other remote-sensing techniques, consists of the ice-buried bedrock surface. Both evolved through long and slow geologic processes. Effects of glacial erosion and deposition dominate everywhere in Antarctica, and erosional effects of running water are relatively minor. Yet, on warm summer days, rare and short-lived streams of glacial melt water do locally exist. Antarctica, with an average elevation of about 7,200 feet (2,200 metres) above sea level, is the world’s highest continent. International concern is increasing over the possibility of global warming. The glaciers and ice sheets of Antarctica may document such change, especially in West Antarctica. Average winter temperatures on the Antarctic Peninsula have increased by 10.8 °F (6 °C) since 1960, and the disintegration of much of the Larsen Ice Shelf  was largely attributed to climatic changes resulting from rising average air temperatures. Many factors determine Antarctica’s climate, but the primary one is the geometry of the Sun-Earth relationship. The 23.5° axial tilt of Earth to its annual plane of orbit, or ecliptic, around the Sun results in long winter nights and long summer days alternating between both polar regions and causing seasonal variations in climate. 

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