In a collaboration between Indiana University’s School of Optometry and the University of California, Davis, Department of Ophthalmology and Vision Science, researchers for the first time have captured the process of disc shedding in a living human eye, providing new understanding of the daily disposal and regeneration of the end tips of photoreceptor cells.
The pioneering achievement in ophthalmic imaging could soon lead to new breakthroughs in eye health.
Combines two imaging technologies for a breakthrough
“Our method combines two imaging technologies: adaptive optics, a technology first used in ground-based telescopes to correct aberrations induced by atmospheric turbulence, and optical coherence tomography — OCT — which makes cross-sectional images,” explains lead researcher Professor Donald T Miller in Indiana University’s School of Optometry. “Combined, the two methods provide exquisite optical resolution, permitting individual cells in the retina (e.g., photoreceptor cells) to be captured in all three dimensions — length, width and depth.”
However, Miller adds that he and his colleagues took it a step further and actually tracked and monitored cone photoreceptor cells over time, thus adding a forth dimension to the image capture. As a consequence, the post-processing required sophisticated algorithms, which the team has developed.
What’s new and unique about the method
“What is amazing about this technology is that it allows us to monitor and track the operation of individual cone cells, all in the living human eye and non-invasively,” Miller notes. “Even though the eye has over four million cone photoreceptors, we can pick which ones we want to look at.”
Photoreceptor health is inherently connected to cell physiology, yet methods to probe this aspect of photoreceptors has been highly limited. This is where the novel imaging method could represent a promising solution. “Our technology opens the door to monitor one of the most sought-after physiological events of these cells: disc shedding,” says the expert in advanced ophthalmic imaging. He elaborates that this event is believed to be disrupted in numerous eye diseases, and thus a likely early indicator of disease onset as well as a sensitive biomarker of disease progression and treatment.
One of the biggest challenges with this research project was simply catching the cone shedding event, according to Miller: “It happens quickly, occurs only once a day per cell, and turns out does not occur at the time of day many textbooks say it should occur.”
Impact on future imaging technologies
The new method could impact the advancement of new kinds of ophthalmic imaging technologies in the future. “Our imaging technology offers new ways to look at the retina that current clinical systems cannot,” Miller emphasizes. “The ultimate goal is that these new findings will help drive the ophthalmologic industry to develop better systems that will lead to improved patient care.”
Now that Miller and his collaborators have for the first time detected photoreceptor disc shedding in the living eye, using this new imaging method, what is next? “We now have planned a series of detailed studies that will look at the dynamics of disc shedding across the entire day, since essentially nothing is known about its occurrence in humans,” the professor says. “This scientific work will set the stage for detailed studies into its impact in diseased eyes.”
The work is detailed in the paper "Photoreceptor disc shedding in the living human eye," co-authored by Donald T Miller and published in OSA’s journal Biomedical Optics Express.
Written by Sandra Henderson, Research Editor, Novus Light Technologies Today