Engineers are working on technology that brings cells in the eye into focus, with the goal of enabling doctors to better diagnose degenerative eye and neurological disorders. The technique relies on adaptive optics, the same method used in astronomy for altering telescope images to visualize stars.
Instead of using complex hardware, the team at the University of Illinois relies on computing power to help scan the retina at the back of the eye. “The eye has always been a bit of a challenge to image,” says Stephen Boppart, an electrical and computer engineering professor at the University of Illinois. “It’s a very complicated organ. There are many microscopic structures that are hard to see. Many diseases that affect vision also start at the microscopic level, so being able to see those early changes is going to lead to better, earlier treatment.”
Traditional optical coherence tomography (OCT) produces a general image of the eye, but is incapable of generating a detailed image of individual rods and cones, the light-sensitive cells that allow us to see. Additionally, OCT can produce blurry images due to motion.
By adding complex algorithms to OCT data, the researchers were able to correct blurs and produce high-resolution images that show individual nerves and cells.
According to Steve Briggs, a biomedical engineer with Edmund Optics who was not involved with the research, this technology is not new per se. “The University of Rochester first imaged rods/cones of the eye with an AO system,” he says, adding that “researchers today are no longer working on a single imaging modality, but rather have moved toward coupling various technologies such as AO, OCT, and various light based microscopy techniques (confocal, multiphoton, super resolution, etc.).”
Indeed, other adaptive optics systems have been created for the purpose of enhancing image quality in OCT. However, Boppart says they’ve been largely hardware-based and feature elaborate setups that make them difficult to use in clinical settings. He adds that his system could easily be integrated into existing OCT systems, while older models may require minimal hardware updates.
“I think computational adaptive optics can be really helpful to the clinical community,” says Fredrick South, a graduate student who worked with Boppart. “It could give ophthalmologists information that, currently, they have to infer from other measurements. They can’t directly look at the photoreceptors and watch them die off during macular degeneration, for example. They just have to guess what’s going on. It could be possible to use computational adaptive optics in these real-world applications both for diagnosis of disease and tracking of treatments.”
Briggs says the ability to correct for aberrations caused by refractive index changes in the eye is a significant step forward for non-invasive imaging. “If we can take this technology to the next level and image through various layers of epidermal tissue, then there is no telling what we could test and diagnose from the comfort of our homes,” he shares. “If one could determine whether or not a skin lesion is a form of melanoma or if it’s simply a cellular anomaly, than we can do various levels of prescreening to treat and possibly cure millions of cases of skin cancer.”
The team is currently using its technology to track macular degeneration related to aging, along with multiple sclerosis.
However, Briggs explains that one of the key issues with this type of technology is the illumination source, adding that adaptive optics today are not advanced enough to correct for these “orders of aberration.”
The only sources that could achieve the required irradiance level is a femtosecond pulsed lasers in the NIR spectrum (750 - 1300nm) – these have price tags that start in the $100,000 range,” he says. “Some of the most popular types being Ti:Sapphire lasers.”
Boppart and his team recently published their work in the journal Nature Photonics. For more information, visit the University of Illinois’ website .
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