New Scope Uses Infrared Light to Image Inner Ear

The new instrument functions like a conventional otoscope and could improve diagnosis of ear infections.

Kristopher Sturgis

MIT researchers and a physician at Connecticut Children's Medical Center have developed a new device to help doctors see deeper inside the ear to look for signs of infection.

For years, doctors have relied on otoscopes to look inside the ear for signs of infection, but these devices rely on visible light, providing views of only a few millimeters deep into the tissues of the ear.

The new device, which was designed to look and function like conventional otoscopes, uses shortwave infrared light to penetrate much deeper into the ear, allowing doctors to see behind the eardrum where infections most often occur. Jessica Carr, an MIT doctoral student and one of the authors on the research, says that their new device was designed to improve on existing otoscope devices.

"In both the conventional and our new otoscope, light is shone on the ear, and the eardrum and ear structures reflect some of this light back," she says. "In a conventional otoscope, the eye or a camera is used to detect the visible light reflecting back. Our otoscope works the same way, except we detect the shortwave infrared light, which cannot be seen by the eye, with our camera. Shortwave infrared light interacts less with tissue than visible light does, allowing it to travel more easily through the eardrum."

Carr explained that the most significant diagnostic sign of an ear infection is the buildup of fluid behind the eardrum. If no fluid is present, then there is no chance of an infection. Unfortunately, conventional otoscopes don't allow doctors to see through the eardrum, making it difficult to know if there is an infection is present.

While there have been more advanced systems to help doctors detect fluid levels in deeper areas of the ear, these methods have not been widely adopted. These methods involve instruments that require special training to operate, and require much more time and effort than traditional methods. Taking this into consideration, Carr and her colleagues have designed this new device to look and function like conventional otoscopes.

"The other methods that exist, such as optical coherence tomography, image the ear--but the image produced by these devices is very different from the images produced by a conventional otoscopes," Carr says. "These devices have not been clinically adopted for ear imaging, one reason being that that they require additional training for practitioners to interpret the results. Practitioners are more comfortable with direct visualization of the ear, which is an advantage that our device can provide."

One of the biggest impacts the device could have is the elimination of misdiagnosis of ear infections that can lead to the unnecessary use of antibiotics. Carr explains that studies have shown that an estimated 8 million children are diagnosed with ear infections in the U.S. each year, but only 51 percent of them actually have middle-ear infections. Of the 49 percent that are misdiagnosed, about half are false negatives, meaning roughly 2 million children every year are prescribed unnecessary antibiotics.

The growing concern over human resistance to antibiotics has been linked to the overuse of antibiotics, and has even prompted specific studies to examine specific instances of infection intolerance. Earlier this year a new DARPA-funded study was carried out by the Wyss Institute for BIologically Inspired Engineering at Harvard to better understand human resistance to deadly superbug infections.

Carr and her colleagues believe this device can help eliminate the use of unnecessary antibiotics, which should go a long way toward addressing the superbug epidemic. The group is currently working on a second prototype of the device which should be easier to use, and more adaptable to all ages and ear sizes. If all goes well, Carr says they hope to have a general set of ready-to-use prototypes for clinical use within the next two or three years. 

Kristopher Sturgis is a contributor to Qmed.

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[Image courtesy of MIT]