Johns Hopkins University

Duke University

Boris I Gramatikov

David Lee Guyton

Kristina Irsch

Joseph A Izatt

Cynthia A Toth

Oscar M Carrasco-Zevallos

Kurt Simons

Howard S Ying

David Guyton

Robert Geary

Jing Tian

An optical apparatus uses polarized light to interrogate birefringence properties of the retina to detect the fixation condition of the eye by sensing characteristic birefringence patterns of the retinal structures. Optical components, as well as optional additional components, interfere with the polarization measurements by introducing unwanted retardance which alters the polarization state of the light entering the eye and of the light reaching the detection system. Compensating retarders are provided to nullify the effect of unwanted retardance in the forward and return light paths so the polarization states of the light entering the eye and the light reaching the detection system are not contaminated by the effects of the unwanted retardance. Mueller matrices are used to mathematically calculate the parameters for the compensating retarders for the unwanted retardance. A variable retarder system may also be provided to compensate for the corneal birefringence of the eye via feedback control.

Compensating for polarization changes introduced by components with retardation in polarization-sensitive retinal scanning systems

An eye alignment monitor and method are described for the detection of variability of the relative alignment of the two eyes with each other, thereby detecting deficits of binocular function, for use as a screening device for these abnormalities especially in infants and young children. Each embodiment includes means for tracking of the positions of a subject's two eyes simultaneously, and furthermore includes repetitive calculation of the relative positions of the two eyes with respect to each other. The embodiments do not require fixation by either eye on a specific point. Typically, a movie on a video display is used for viewing by the subject. Variability of relative alignment of the two eyes with each other is typically determined by variability of the relative positions of images of the pupils of the eyes with respect to each other over time.

Eye alignment monitor and method

The present invention provides for very fast detection of gaze direction using retro-reflected light from the ocular fundus that is cost-efficient, small, and portable. These eye trackers are useful in many areas of science and technology, including but not limited to remote control, space, defense, medical and psycho-physiological applications, to identify for example subtle neurologic deficits that occur with cerebellar or vestibular disorders, Parkinson's disease, strokes, traumatic brain injury, possible concussions during sports matches, some forms of reading disability, or simply fatigue or inebriation. In ophthalmology, with two such devices operating simultaneously, the variability of relative eye alignment over time can be measured, without requiring individual calibration, and without requiring fixation on a specified target, ideal for use with small children. Such instruments have widespread application as noninvasive screening devices in infants and young children or patients of any age for defects of binocular function such as strabismus and amblyopia.

Fast X-Y axis bright pupil tracker

The present invention is directed to a method and system for improved aiming during Optical Coherence Tomography (OCT) on young children and those unable to cooperate with OCT imaging by synchronization with retinal birefringence scanning (RBS). OCT is performed without knowing whether or not the subject is looking at the intended target. The present invention combines OCT retinal imaging, such as, but not limited to, time domain OCT, SDOCT, or SSOCT, with RBS technology that provides accurate information on the presence or absence of foveal fixation. Therefore, the present invention only analyzes data during foveal fixation. A system combining OCT with RBS is implemented such that both systems co-operate in a specified alignment, such that when the RBS fixation detection system detects alignment with the fovea of the eye, the OCT system will be aimed at the retinal region of interest, usually but not necessarily including the macular area.

Method and system for improving aiming during optical coherence tomography on young children by synchronization with retinal bifringence scanning

An eye tracking and gaze fixation detection system, includes an electronically scannable optical illumination system emits polarized near-infrared (NIR) light to a retina in an eye of a subject; an optical detection system arranged in an optical path of the NIR light after being reflected from the retina of the eye of the subject, the optical detection system providing a detection signal; and a signal processing system communicates with the optical detection system to receive the detection signal, wherein the optical illumination system emits the polarized NIR light to illuminate at least a portion of a scanning path, wherein the scanning path is a spatially closed loop across a portion of the retina in the eye of the subject that repeats periodically over time, and wherein the signal processing system is configured to determine at least one of a gaze direction and a gaze fixation based on the detection signal.

Eye tracking and gaze fixation detection systems, components and methods using polarized light

The present invention provides apparatus and methods for detecting fixation of an eye of a subject on a target. The methods provide for optimization of parameters of the spinning half wave plate and the fixed wave plate in the retinal birefringence scanning (RBS) design to enable uses of the 'spinning artifact' frequency component. Frequency of the 'spinning artifact' component is determined by half wave plate rotation speed and direction. Amplitude is determined by interaction of the spinning half wave plate with any retardance encountered in the double-pass optics such as the fixed wave plate, corneal birefringence, and small amount of retinal birefringence. With optimum selection of fractional spinning frequency of the half wave plate, and the orientation/retardance of the fixed wave plate, the &#x201c;spinning artifact&#x201d; frequency component is essentially independent of fixation direction and is also essentially independent of the normal range of corneal birefringence.

Apparatus and method for minimizing the influence of corneal birefringence on the analysis of eye fixation and focus using retinal birefringence scanning

An apparatus for detecting fixation of at least one eye of a subject on a target includes an optical illumination system, an optical detection system, and a signal processing system adapted to communicate with the optical detection system. The signal processing system is configured to calculate at least one of a time-frequency distribution or an Auto-Regressive spectral estimation of the detection signal to provide a frequency distribution of the detection signal at a plurality of times for use in determining periods in which the subject's eye is fixed on the target based on the first and second frequency signatures.

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Baltimore, MD, United States of America

Boris I Gramatikov