In a recent study published in Optics Letters, investigators from the Medical University of Vienna in Austria outlined their breakthrough research on an innovative device with the potential to be a low-cost alternative for swept-source optical coherence tomography (SS-OCT).
Give me some background.
Using a vertical-cavity surface-emitting laser (VCSEL) diode, which is more often used in the context of telecommunications, light detection, and ranging (LIDAR), researchers established the use of a less expensive light source for modified SS-OCT machines.
In addition to the VCSEL diode, investigators introduced other components to maintain the system performance and advanced post-processing algorithms.
Tell me more.
By fluctuating the operating temperature of the single-mode VCSEL diode, researchers produced changes in the light wavelength necessary for SS-OCT.
They then induced a temperature change by increasing the driving current over a short period of time beyond the original specifications of the VCSEL diode.
A cooling period followed to prevent the deterioration of the diode material, allowing users to “tune the diode over a wider bandwidth than is otherwise possible,” explained Milana Kendrisic, a study investigator.
How did they avoid eye damage?
While previous research has shown that VCSELs can be employed for OCT machines, those setups were not designed to image eyes.
To avoid damaging the eye while scanning, the VCSEL designed by the researchers operates at 850 nm, which isn’t strongly absorbed by water, and by extension, the eye.
Consequently, this would make it possible for the laser to emit light that can travel through the eye to the retina and back without losing the signal to absorption.
How did they test the system?
To demonstrate the system performance in vivo, a volunteer with healthy eyes was imaged, and full-eye scans were acquired at 25 and 50 kHz from the cornea to the retina.
And the purpose?
Kendrisic highlighted that the team wanted “to develop a low-cost OCT device that could be used in a general practitioner’s office, pharmacy, or even supermarket to allow eye checkups without going to the ophthalmologist … to monitor treatment or catch abnormal changes early, avoiding loss of vision and ultimately preserving the [patient’s] quality of life.”
Give me the big picture.
While OCT systems remain relatively inaccessible due to the price of lasers and their complexity, this breakthrough signals the potential for future at-home OCT devices.
As Kendrisic observed, “These laser diodes could cost as little as a few dollars each if bought in bulk.”
Further large-scale clinical studies are necessary to evaluate the OCT system’s potential clinical utility.