A new optical device puts the power to detect eye disease in the palm of a hand. The tool — about the size of a handheld video camera — scans a patient's entire retina in seconds and could aid primary care physicians in the early detection of a host of retinal diseases. The new design is the first to combine cutting-edge technologies such as ultrahigh-speed 3D imaging, a MEMS mirror for scanning, and a technique to correct for unintentional movement by the patient.
The instrument uses optical coherence tomography (OCT) that sends beams of infrared light into the eye and onto the retina. Echoes of this light return to the instrument, which uses interferometry to measures changes in the time delay and magnitude of the returning light echoes, revealing the cross sectional tissue structure of the retina — similar to radar or ultrasound imaging.
The researchers tested two designs, one of which is similar to a handheld video camera with a flat-screen display. To deal with the motion instability of a handheld device, the instrument takes multiple 3D images at high speeds, scanning a particular volume of the eye many times but with different scanning directions. By using multiple 3D images of the same part of the retina, it is possible to correct for distortions due to motion of the operator's hand or the subject's own eye.