A saccade is a quick, simultaneous movement of both eyes between two or more phases of fixation in the same direction. In contrast, in smooth-pursuit movements, the eyes move smoothly instead of in jumps. The phenomenon can be associated with a shift in frequency of an emitted signal or a movement of a body part or device. Controlled cortically by the frontal eye fields (FEF), or subcortically by the superior colliculus, saccades serve as a mechanism for fixation, rapid eye movement, and the fast phase of optokinetic nystagmus. The word appears to have been coined in the 1880s by French ophthalmologist Émile Javal, who used a mirror on one side of a page to observe eye movement in silent reading, and found that it involves a succession of discontinuous individual movements.
Peripheral vision, or indirect vision, is vision as it occurs outside the point of fixation, i.e. away from the center of gaze or, when viewed at large angles, in the "corner of one's eye". The vast majority of the area in the visual field is included in the notion of peripheral vision. "Far peripheral" vision refers to the area at the edges of the visual field, "mid-peripheral" vision refers to medium eccentricities, and "near-peripheral", sometimes referred to as "para-central" vision, exists adjacent to the center of gaze.
The field of view (FOV) is the angular extent of the observable world that is seen at any given moment. In the case of optical instruments or sensors, it is a solid angle through which a detector is sensitive to electromagnetic radiation. It is further relevant in photography.
Scanning laser ophthalmoscopy (SLO) is a method of examination of the eye. It uses the technique of confocal laser scanning microscopy for diagnostic imaging of the retina or cornea of the human eye.
The fovea centralis is a small, central pit composed of closely packed cones in the eye. It is located in the center of the macula lutea of the retina.
A scotoma is an area of partial alteration in the field of vision consisting of a partially diminished or entirely degenerated visual acuity that is surrounded by a field of normal – or relatively well-preserved – vision.
The visual field is "that portion of space in which objects are visible at the same moment during steady fixation of the gaze in one direction"; in ophthalmology and neurology the emphasis is mostly on the structure inside the visual field and it is then considered “the field of functional capacity obtained and recorded by means of perimetry”.
Eye tracking is the process of measuring either the point of gaze or the motion of an eye relative to the head. An eye tracker is a device for measuring eye positions and eye movement. Eye trackers are used in research on the visual system, in psychology, in psycholinguistics, marketing, as an input device for human-computer interaction, and in product design. In addition, eye trackers are increasingly being used for assistive and rehabilitative applications such as controlling wheelchairs, robotic arms, and prostheses. Recently, eye tracking has been examined as a tool for the early detection of autism spectrum disorder. There are several methods for measuring eye movement, with the most popular variant using video images to extract eye position. Other methods use search coils or are based on the electrooculogram.
Meridian is used in perimetry and in specifying visual fields. According to IPS Perimetry Standards 1978 (2002): "Perimetry is the measurement of [an observer's] visual functions ... at topographically defined loci in the visual field. The visual field is that portion of the external environment of the observer [in which when he or she is] steadily fixating ...[he or she] can detect visual stimuli."
Eye movement includes the voluntary or involuntary movement of the eyes. Eye movements are used by a number of organisms to fixate, inspect and track visual objects of interests. A special type of eye movement, rapid eye movement, occurs during REM sleep.
Fixation or visual fixation is the maintaining of the gaze on a single location. An animal can exhibit visual fixation if it possess a fovea in the anatomy of their eye. The fovea is typically located at the center of the retina and is the point of clearest vision. The species in which fixational eye movement has been verified thus far include humans, primates, cats, rabbits, turtles, salamanders, and owls. Regular eye movement alternates between saccades and visual fixations, the notable exception being in smooth pursuit, controlled by a different neural substrate that appears to have developed for hunting prey. The term "fixation" can either be used to refer to the point in time and space of focus or the act of fixating. Fixation, in the act of fixating, is the point between any two saccades, during which the eyes are relatively stationary and virtually all visual input occurs. In the absence of retinal jitter, a laboratory condition known as retinal stabilization, perceptions tend to rapidly fade away. To maintain visibility, the nervous system carries out a procedure called fixational eye movement, which continuously stimulates neurons in the early visual areas of the brain responding to transient stimuli. There are three categories of fixational eye movement: microsaccades, ocular drifts, and ocular microtremor. At small amplitudes the boundaries between categories become unclear, particularly between drift and tremor.
Within computer technology, the gaze-contingency paradigm is a general term for techniques allowing a computer screen display to change in function depending on where the viewer is looking. Gaze-contingent techniques are part of the eye movement field of study in psychology.
In vision science, stabilized Images are images that remain immobile on the retina. Under natural viewing conditions, the eyes are always in motion. Small eye movements continually occur even when attempting fixation. Experiments in the early 1950s established that stabilized images result in the fading and disappearance of the visual percept, possibly due to retinal adaptation to a stationary field. In 2007, studies indicated that stabilizing vision between saccades selectively impairs vision of fine spatial detail.
Parafovea or the parafoveal belt is a region in the retina that circumscribes the fovea and is part of the macula lutea. It is circumscribed by the perifovea.
SensoMotoric Instruments (SMI) was a German provider of dedicated computer vision applications with a major focus on eye-tracking technology. SMI was founded in 1991 as a spin-off from academic and medical research at the Free University of Berlin. The company has its headquarters in Teltow near Berlin, Germany, offices in Boston, Massachusetts and San Francisco, California, in the United States, and a worldwide distributor and partner network.
Microperimetry, sometimes called fundus-controlled perimetry, is a type of visual field test which uses one of several technologies to create a "retinal sensitivity map" of the quantity of light perceived in specific parts of the retina in people who have lost the ability to fixate on an object or light source. The main difference with traditional perimetry instruments is that, microperimetry includes a system to image the retina and an eye tracker to compensate eye movements during visual field testing.
Retinal birefringence scanning (RBS) is a method for detecting the central fixation of the eye. The method can be used in pediatric ophthalmology for screening purposes. By simultaneously measuring the central fixation of both eyes, small- and large-angle strabismus can be detected. The method is not invasive and requires little cooperation by the patient, so it can be used for detecting strabismus in young children. The method provides a reliable detection of strabismus and has also been used for detecting certain kinds of amblyopia. RBS uses the human eye's birefringent properties to identify the position of the fovea and the direction of gaze, and thereby to measure any binocular misalignment.
A virtual reality headset is a head-mounted device that uses 3D near-eye displays and positional tracking to provide a virtual reality environment for the user. VR headsets are widely used with VR video games, but they are also used in other applications, including simulators and trainers. VR headsets typically include a stereoscopic display, stereo sound, and sensors like accelerometers and gyroscopes for tracking the pose of the user's head to match the orientation of the virtual camera with the user's eye positions in the real world.
The Snapdragon Qualcomm VR820 is a virtual reality reference platform that was released in Q4 2016, with the first commercial devices based on the platform available shortly thereafter. It is based on the Qualcomm Snapdragon 820 processor, released on November 10, 2015.
Foveated rendering is a rendering technique which uses an eye tracker integrated with a virtual reality headset to reduce the rendering workload by greatly reducing the image quality in the peripheral vision.
