High-speed, image-based eye tracking with a scanning laser ophthalmoscope

In this report, which is an international collaboration of OCT, adaptive optics, and control research, we demonstrate the data-based online nonlinear extremum-seeker (DONE) algorithm to guide the image based optimization for wavefront sensorless adaptive optics (WFSL-AO) OCT for in vivo human retinal imaging. The ocular aberrations were corrected using a multi-actuator adaptive lens after linearization of the hysteresis in the piezoelectric actuators. The DONE algorithm succeeded in drastically improving image quality and the OCT signal intensity, up to a factor seven, while achieving a computational time of 1 ms per iteration, making it applicable for many high speed applications. We demonstrate the correction of five aberrations using 70 iterations of the DONE algorithm performed over 2.8 s of continuous volumetric OCT acquisition. Data acquired from an imaging phantom and in vivo from human research volunteers are presented.

Section: Discussionmentioning

confidence: 99%

Wavefront sensorless adaptive optics OCT with the DONE algorithm for in vivo human retinal imaging [Invited]

Verstraete

Heisler

et al. 2017

“…It could be possible to extract motion information and use this to track the eye's movement. When done fast enough, it will also enable doing eye motion correction in real-time [32,33] to improve the quality of the images by averaging multiple images at the same location and correct for the minor motion artefacts present in these images. Image registration could potentially be better with the parallel illumination as all the illumination points of a single frame are undistorted.…”

Section: Discussionmentioning

confidence: 99%

Digital micromirror device based ophthalmoscope with concentric circle scanning

Damodaran

Vienola

Braaf

et al. 2017

Self Cite

Abstract:Retinal imaging is demonstrated using a novel scanning light ophthalmoscope based on a digital micromirror device with 810 nm illumination. Concentric circles were used as scan patterns, which facilitated fixation by a human subject for imaging. An annular illumination was implemented in the system to reduce the background caused by corneal reflections and thereby to enhance the signal-to-noise ratio. A 1.9-fold increase in the signal-to-noise ratio was found by using an annular illumination aperture compared to a circular illumination aperture, resulting in a 5-fold increase in imaging speed and a better signal-to-noise ratio compared to our previous system. We tested the imaging performance of our system by performing nonmydriatic imaging on two subjects at a speed of 7 Hz with a maximum 20 • (diameter) field of view. The images were shot noise limited and clearly show various anatomical features of the retina with high contrast.

“…We used the 808 nm StopLine single-notch filter (Semrock, Rochester, NY) which, when used at 45°, allows for nearly 100% of the 730 nm TSLO beam to reflect onto the eye, with the other wavelengths of the AOSLO transmitting through the filter. The TSLO design and set-up have been described in detail in a previous publication [15]. Briefly, a series of three telescopes are used to relay the pupil of the eye onto both horizontal and vertical scanners, with a photomultiplier tube (PMT) used to capture the reflected scanned retinal image.…”

Section: System Hardwarementioning

confidence: 99%

“…The system acts similar to a woofer-tweeter eye-tracking system; utilizing both software (digital tracking) and an active tilt/tip mirror (optical tracking) in order to achieve real-time image stabilization and correction. It has been shown in previous work with the TSLO system that the allowable eye motion/velocity threshold for digital tracking scales linearly with a system's field size [15]. Therefore, using an external tracking system with a larger field of view (FOV) to guide/steer the AOSLO imaging beam allows for more eye motion to be captured than with the AOSLO system alone.…”

Section: Introductionmentioning

confidence: 99%

Active eye-tracking for an adaptive optics scanning laser ophthalmoscope

Sheehy

Tiruveedhula

Sabesan

et al. 2015

Self Cite

Abstract:We demonstrate a system that combines a tracking scanning laser ophthalmoscope (TSLO) and an adaptive optics scanning laser ophthalmoscope (AOSLO) system resulting in both optical (hardware) and digital (software) eye-tracking capabilities. The hybrid system employs the TSLO for active eye-tracking at a rate up to 960 Hz for real-time stabilization of the AOSLO system. AOSLO videos with active eyetracking signals showed, at most, an amplitude of motion of 0.20 arcminutes for horizontal motion and 0.14 arcminutes for vertical motion. Subsequent real-time digital stabilization limited residual motion to an average of only 0.06 arcminutes (a 95% reduction). By correcting for high amplitude, low frequency drifts of the eye, the active TSLO eye-tracking system enabled the AOSLO system to capture high-resolution retinal images over a larger range of motion than previously possible with just the AOSLO imaging system alone.