Optical Imager Could Help Diagnose, Treat Dry Eye Disease

A new, noninvasive optical imaging system promises to improve diagnosis and treatment for dry eye disease. Called the Tear Film Imager, the device has the ability to perform spectral measurements across a large field of view in a few seconds and can acquire fast and consistent measurements from a blinking human eye.

The Tear Film Imager uses an eye-safe halogen light to illuminate the eye and then analyzes the full spectrum of light reflection over time and space. These spectral measurements are used to reconstruct the structures found in the front of the eye, allowing accurate measurement of the tear film inner layers, especially the aqueous sublayer, which plays an important role in dry eye but has been difficult to analyze with other methods.

The Tear Film Imager captures a raw image (a) and also generates a thickness map (b) derived from the color information at each pixel. This can be used to distinguish the tear film’s inner layers. Courtesy of AdOM Advanced Optical Methods Ltd.

“The broadband illumination source and fine details available from spectral analysis provide nanometer-level insight into subtle changes in each tear film layer and sublayer,” said research team leader Dr. Yoel Arieli from AdOM Advanced Optical Methods Ltd. “These measurements are completed automatically in just 40 seconds.”

After demonstrating a resolution of 2.2 nm on a mock tear film, the researchers tested the instrument’s ability to take measurements on the human eye with no intervention while the patient was blinking. “The device worked impressively and presents no risk because it is noninvasive and uses a simple light source,” Arieli said. “It not only measured the tear film consistently including blinks every few seconds, but the measurements correlated well with other partially invasive, established dry eye diagnostic techniques.”

The Tear Film Imager has been used in two clinical studies in Israel and Canada for dry eye diagnosis and dry eye treatments, which can be precisely evaluated with the imager. The researchers said that future studies could help inform better dry eye treatments, improve surgical outcomes, and lead to more accurate fitting of contact lenses. They are planning to use the Tear Film Imager in larger studies with more diverse groups of patients to set base levels for both healthy eyes and people with dry eye.

“Up to 60% of ophthalmology office visits are due to dry eye, pointing to the need for a noninvasive and highly accurate device for diagnosis in the office setting,” Arieli said. “Our Tear Film Imager is the first device that can be used in the ophthalmology or optometry setting to image the tear film and distinguish its inner layers with nanometer resolution.”

The research was published in Applied Optics, a publication of The Optical Society (OSA) (www.doi.org/10.1364/AO.58.007987).