Revolutionizing Diagnostics: Dr. Applegate and the OCT Otoscope

Plato famously wrote in The Republic that “our need will be the real creator,” which eventually transformed into the proverb “necessity is the mother of invention.” While Dr. Brian Applegate, PhD, likely didn’t have this exact phrase in mind as he and his team began developing the optical coherence tomography (OCT) otoscope, necessity is at the core of the innovative work he has done to make improvements on one of the most important diagnostic tools in otolaryngology–the otoscope.

The standard otoscope has been around for more than 100 years, with its initial form originating in the 1830s with French inventor Jean-Pierre Bonnafont, who discovered that he was able to better see into the ear canal if he directed a light source into the ear using a mirror. Bonnafont’s “speculum autostatique” was later improved upon by British military doctor John Brunton, who figured out a way to design the otoscope to allow more light in, and according to Applegate, the only real significant progress that has been made on the otoscope over the past century (at least until now) has been the addition of the video camera. While the standard otoscope can provide valuable visual information relevant to determining treatment options, Applegate and his team wondered if OCT could potentially offer a means by which to detect signs of middle ear disease before it became clinically apparent (i.e. when the patient already has hearing loss), thus allowing for earlier and more effective interventions.

Although Applegate earned his PhD in physical chemistry from The Ohio State University, he pursued training in biomedical engineering as a postdoctoral fellow at Duke University. His initial interest was in spectroscopy, or the study of the absorption and emission of light and other radiation by matter, but under the guidance of Professor Joe Izatt, he shifted his focus to creating molecular imaging approaches for OCT, an imaging technique that uses low-coherence light to capture high-resolution, cross-sectional images. OCT was originally used on the eye; however, when Applegate joined the faculty of Texas A&M University, advancing to the rank of Associate Professor of Biomedical Engineering, he met Dr. John S. Oghalai, MD, an assistant professor at the Baylor College of Medicine, with whom he would collaborate to use OCT to instead look at the deeper structures of the ear. He and Oghalai ultimately brought this collaboration over to USC, with Oghalai currently serving as the Department Chair for the USC Caruso Department of Otolaryngology-Head and Neck Surgery.

As Applegate and Oghalai continued their work together, using OCT to study cochlear mechanics in mice, they started to consider that perhaps they could find a way to use OCT to measure functionality in the middle ear in humans. They tested their theory through the use of a surgical microscope, and based on the high quality of those images, they were inspired to build a handheld version (the OCT otoscope) that they hoped could one day be produced at a price point low enough that this revolutionary diagnostic tool could become widely accessible. As an example of why this matters, while the standard otoscope enables doctors to examine the tympanic membrane (otherwise known as the eardrum) for visual abnormalities–in a healthy ear, the tympanic membrane is translucent, whereas if the membrane is cloudy or opaque, it could signal an underlying pathology—the standard otoscope has significant limitations in that it’s difficult to make quantifiable measurements or see below the tympanic membrane. Conversely, the OCT otoscope can actually quantify, say, the thickness of the tympanic membrane, adding valuable diagnostic information that doctors can use to manage and optimize patient care.

Applegate notes that the OCT otoscope evolved over many years rather than resulting from a singular epiphany, with recent advancements in technology and hardware facilitating the creation of the handheld device. For instance, the mirrors that they currently use in the device weren’t available 10 or 20 years ago. When Applegate and Oghalai were doing research using OCT to study cochlear mechanics in mice, they frequently asked themselves questions like, is what we are doing actually helpful? Could it result in something practical? Even as they began to realize that the engineering for the handheld OCT otoscope might be feasible, they still needed to make sure that the device would actually provide helpful information to doctors, a question they could only answer by testing the OCT otoscope in a clinical setting.

Applegate details how the design of the OCT otoscope evolved over time as well. In the first iteration, Applegate and his team were primarily focused on figuring out the shape and format, including who was going to use this device and how they were going to use it, given that an engineer and a clinician might have different ideas about what they ideally want. After that, the next priority was to improve on the field of view–earlier versions of the OCT otoscope obtained a lower distortion image, but the higher quality of the image meant a smaller field of view. They decided to go in the other direction, creating a version that had a much bigger field of view but much more distortion, as post-processing could then be used to make image corrections.

With regard to next steps, Applegate hopes to work on two parallel plans to increase the accessibility of the OCT otoscope so that it can be used to serve more patients. One of those plans is to find ways to reduce the cost of the OCT otoscope that is already in use, which Applegate believes could be adjusted in ways that would diminish the cost by roughly 40%. The other parallel plan would be to figure out strategies for designing a new version of the OCT otoscope that is at a much lower price point than even the more affordable version mentioned above. If the logistical challenges of engineering such a device could be overcome, it would mean that the OCT otoscope could end up in the offices of primary care physicians rather than solely existing under the purview of specialists. Given that normally, the left and right ear are basically mirror images of one another, this means that a primary care physician could use asymmetries in the images to determine whether a patient should see an ENT even before they were exhibiting any clinically significant signs of disease.

When asked what advice he would give to someone interested in doing translational research and developing more advanced diagnostic tools, Applegate stressed the significance of finding a good collaborator, which he says is not an easy thing to do and oftentimes takes some combination of persistence and luck. He recommends that new researchers try lots of different things to see what pans out, persevering when challenges arise and taking advantage of opportunities as they come along.