In L. Frank Baum's classic novel "The Wonderful Wizard of Oz," the Emerald City dazzles visitors with its vibrant green shade, enhanced through the use of green-tinted glasses. This idea of manipulating perception has now found a novel application in the world of science. Researchers at the University of California, Berkeley, have developed a technique enabling the human eye to perceive a new color, named "olo," with unprecedented saturation. The technique, dubbed “Oz,” involves precise manipulation of photoreceptors in the eye using tiny doses of laser light.

According to Austin Roorda, professor of optometry and vision science at UC Berkeley and one of the creators of Oz, the color olo is akin to a deeply saturated teal, surpassing the intensity of any natural hue. The researchers' method controls up to 1,000 photoreceptors simultaneously to display not only this new color but also a variety of other images. The system holds potential for exploring fundamental questions about human vision and its limitations.

James Carl Fong, a doctoral student in electrical engineering and computer sciences at UC Berkeley, explained, “We’ve created a system that can track, target, and stimulate photoreceptor cells with such high precision that we can now answer very basic, but also very thought-provoking, questions about the nature of human color vision.”

The Oz technique was published in the journal Science Advances and received funding from federal sources like the National Institutes of Health and the Air Force Office of Scientific Research. The concept sprouted from an investigation into the overlap of light wavelengths affecting M and L cone cells in the human retina. Ren Ng, professor of electrical engineering and computer sciences at UC Berkeley, and a senior author of the study, expressed wonder about the outcomes of stimulating M cone cells specifically.

Co-lead author Hannah Doyle from UC Berkeley managed the human experiments, wherein five subjects, including Roorda and Ng, experienced the color olo. Doyle described olo as a unique blue-green or peacock green, much more vibrant than typical monochromatic hues.

The researchers partnered with specialists from the University of Washington to map individual cone cells, allowing accurate targeting within the retina. By precisely orchestrating laser pulses to activate specific cone arrangements, the Oz technique can project an array of visual experiences directly into the human eye.

Beyond its ability to showcase novel colors, Oz offers new avenues for studying eye diseases and potential treatments. Its cone-by-cone activation capacity holds promise for simulating vision impairments in healthy subjects, aiding the understanding of diseases that cause visual impairment.

The research included contributions from Congli Wang, Alexandra E. Boehm, Sophie R. Herbeck, Brian P. Schmidt, Pavan Tiruveedhula, John E. Vanston, and William S. Tuten, and was supported by a Hellman Fellowship, FHL Vive Center Seed Grant, among others.

Roorda pondered the broader implications of the research: "It’s still a mystery whether, if you expand the signals or generate new sensory inputs, will the brain be able to make sense of them and appreciate them? And, you know, I like to believe that it can," emphasizing the brain's ability to adapt to new stimuli.