Low-Cost Retinal Scanner Could Help Prevent Blindness Worldwide

By

DURHAM, N.C.—Biomedical engineers at Duke University have developed a low-cost, portable optical coherence tomography (OCT) scanner that promises to bring the vision-saving technology to underserved regions throughout the U.S. and abroad. Thanks to a redesigned, 3D-printed spectrometer, the scanner is 15 times lighter and smaller than current commercial systems and is made from parts costing less than a tenth the retail price of commercial systems—all without sacrificing imaging quality. In its first clinical trial, the new OCT scanner produced images of 120 retinas that were 95 percent as sharp as those taken by current commercial systems, which was sufficient for accurate clinical diagnosis, according to Duke.

The results appear online in the June issue of Translational Vision Science & Technology, an open access ARVO journal. “Our goal is to make OCT drastically less expensive so more clinics can afford the devices, especially in global health settings,” said Adam Wax, professor of biomedical engineering at Duke.


This OCT system designed at Duke
University is 15 times lighter and smaller
than current commercial systems and is
made from parts costing less than a tenth
the retail price of commercial systems.

OCT is the optical analogue of ultrasound, which works by sending sound waves into tissues and measuring how long they take to come back. But because light is so much faster than sound, measuring time is more difficult. To time the light waves bouncing back from the tissue being scanned, OCT devices use a spectrometer to determine how much their phase has shifted compared to identical light waves that have traveled the same distance but have not interacted with tissue.

The primary technology enabling the smaller, less expensive OCT device is a new type of spectrometer designed by Wax and his former graduate student Sanghoon Kim. Traditional spectrometers are made mostly of precisely cut metal components and direct light through a series of lenses, mirrors and diffraction slits shaped like a W. While this setup provides a high degree of accuracy, slight mechanical shifts caused by bumps or even temperature changes can create misalignments.

Wax’s design, however, takes the light on a circular path within a housing made mostly from 3D-printed plastic. Because the spectrometer light path is circular, any expansions or contractions due to temperature changes occur symmetrically, balancing themselves out to keep the optical elements aligned. The device also uses a larger detector at the end of the light’s journey to make misalignments less likely.


A comparison of retinal images taken by the new low-cost OCT system (l) and a
commercial device (r). In its first clinical
trial, the low-cost system produced images
of 120 retinas that were 95 percent as
sharp as those taken by current commercial systems, which was sufficient for accurate clinical diagnosis.

The new OCT device weighs four pounds, is about the size of a lunch box and, Wax expects, will be sold for less than $15,000.

“Right now OCT devices sit in their own room and require a PhD scientist to tweak them to get everything working just right,” said Wax. “Ours can just sit on a shelf in the office and be taken down, used and put back without problems. We’ve scanned people in a Starbucks with it.”

Wax is commercializing the device through a startup company called Lumedica, which is already producing and selling first-generation instruments for research applications. The company hopes to secure venture backing in the near future and is also negotiating potential licensing deals with outside companies.

“There’s a lot of interest from people who want to take OCT to new parts of the globe as well as to underserved populations right here in the U.S.,” said Wax. “With the growing number of cases of diabetic retinopathy in places like the U.S., India and China, we hope we can save a lot of people’s sight by drastically increasing access to this technology.”