Fixational eye movements in passive versus active sustained fixation tasks

Bowers, Norick R.; Gautier, Josselin; Lin, Samantha; Roorda, Austin

doi:10.1167/jov.21.11.16

Cited by 26 publications

(19 citation statements)

References 66 publications

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“…This agrees with observations in the recent literature that empirical FEM statistics change in a task-dependent manner. In particular, the amplitude, speed, and curvature of FEM drift and microsaccades were reported to be distinct between passive viewing and acuity tasks (20). In addition, recent work in primates supports that FEM originate from central neural circuitry generating noise that controls FEM statistics (21), which is consistent with subjects’ ability to modulate FEM amplitude according to stimuli.…”

Section: Discussionmentioning

confidence: 99%

Fixational eye movements as active sensation for high visual acuity

Nghiem

Dufour

Reiniger

et al. 2022

Preprint

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Perception and action are inherently entangled: our world view is shaped by how we explore and navigate our environment through complex and variable self-motion. Even when fixating on a stable stimulus, our eyes undergo small, involuntary movements. Fixational eye movements (FEM) render a stable world jittery on our retinae, which contributes noise to neural coding. Yet, empirical evidence suggests that FEM help rather than harm human perception of fine detail. Here, we elucidate this paradox by uncovering under which conditions FEM improve or impair retinal coding and human acuity. We combine theory and experiment: model accuracy is directly compared to that of healthy human subjects in a visual acuity task. Acuity is modeled by applying an ideal Bayesian classifier to simulations of retinal spiking activity in the presence of FEM. In addition, empirical FEM are monitored using high-resolution eye-tracking by an adaptive optics scanning laser ophthalmoscope. While FEM introduce noise, they also effectively pre-process visual inputs to facilitate retinal information encoding. Based on an interplay of these mechanisms, our model predicts a relation between visual acuity, FEM amplitude, and single-trial stimulus size that quantitatively accounts for experimental observations and captures the beneficial effect of FEM. Moreover, we observe that human subjects’ FEM statistics vary with stimulus size, and our model suggests that changing eye motion amplitude, as the subjects indeed do, enhances acuity as compared to maintaining eye motion size constant. Overall, our findings indicate that perception benefits from action even at the fine and noise-dominated spatio-temporal scale of FEM.Significance StatementPerception is inherently active: we need to move our eyes to see the world around us. Yet our eyes also undergo tiny, unconscious movements that can blur out fine visual details. Paradoxically, previous work suggested that these small movements aid fine detail perception. Here, we investigate this paradox to uncover in which contexts small eye movements help or harm visual acuity. Comparing a model of retinal responses with recordings of human visual acuity, we elucidate the mechanisms by which and conditions in which small eye movements support fine detail discrimination. Our results also suggest that varying eye movement amplitude according to stimulus size enhances retinal coding, highlighting that perception is active even at the level of very fine eye movements.

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Section: Discussionmentioning

confidence: 99%

Fixational eye movements as active sensation for high visual acuity

Nghiem

Dufour

Reiniger

et al. 2022

Preprint

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“…The AMC was determined using a commercial flood-illumination AO camera, which has a relatively low frame capture rate (10 frames per second) compared with AOSLO-based methods. For example, Reiniger et al 20 and Bowers et al 2 used AOSLO cameras that captured 30 and 960 frames per second, respectively. The AMC was derived from the average of the four separate (0,0) coordinates marked by the device using the raw image with the best image quality (according to the manufacturer).…”

Section: Discussionmentioning

confidence: 99%

“…It is well recognized that there is a physiologic instability in the eye position, governed by fixational eye movements, during retinal imaging or microperimetry characterized by a series of slow drifts and microsaccades. 2 Several methods have been used to define the preferred fixation locus, also known as the preferred retinal locus (PRL), such as the centroid of the region encompassing 95% of fixation points used during a fixation task quantified by the bivariate contour ellipse area (BCEA). 3 Given that the greatest diameter of the BCEA used during microperimetry can vary from 0.6° to 1.8° in healthy controls across different age groups, 4 it is not surprising that there is a potential for significant disparity between the PRL and FPC.…”

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confidence: 99%

Impact of Reference Center Choice on Adaptive Optics Imaging Cone Mosaic Analysis

Roshandel

Sampson

Mackey

et al. 2022

Invest. Ophthalmol. Vis. Sci.

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Purpose Foveal center marking is a key step in retinal image analysis. We investigated the discordance between the adaptive optics (AO) montage center (AMC) and the foveal pit center (FPC) and its implications for cone mosaic analysis using a commercial flood-illumination AO camera. Methods Thirty eyes of 30 individuals (including 15 healthy and 15 patients with rod–cone dystrophy) were included. Spectral-domain optical coherence tomography was used to determine the FPC, and flood-illumination AO imaging was performed with overlapping image frames to create an AO montage. The AMC was determined by averaging the (0,0) coordinates in the four paracentral overlapping AO image frames. Cone mosaic measurements at various retinal eccentricities were compared between corresponding retinal loci relative to the AMC or FPC. Results AMCs were located temporally to the FPCs in 14 of 15 eyes in both groups. The average AMC–FPC discordance was 0.85° among healthy controls and 0.33° among patients with rod-cone dystrophy ( P < 0.05). The distance of the AMC from the FPC was a significant determinant of the cone density (β estimate = 218 cells/deg 2 /deg; 95% confidence interval [CI], 107–330; P < 0.001) and inter-cone distance (β estimate = 0.28 arcmin/deg; 95% CI, 0.15–0.40; P < 0.001), after adjustment for age, sex, axial length, spherical equivalent, eccentricity, and disease status. Conclusions There is a marked mismatch between the AMC and FPC in healthy eyes that may be modified by disease process such as rod–cone dystrophy. We recommend users of AO imaging systems carefully align the AO montage with a foveal anatomical landmark, such as the FPC, to ensure precise and reproducible localization of the eccentricities and regions of interest for cone mosaic analysis.

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“…This was carried separately on the horizontal and vertical component of the eye motion, as proposed by Thomson [Thomson 1982[36]], and Babadi and Brown [Babadi Brown 2014[37]]. As in [Bowers et al 2019[38]], the analysis was run on overlapping segments of 1sec. The time half-bandwidth product was fixed at 2.5 and the last taper was dropped to maximize spectral concentration ratios in the Slepian sequences.…”

Section: Methodsmentioning

confidence: 99%

Foveolar drusen decrease fixation stability in pre-symptomatic AMD

Murari,

Gautier,

Daout

et al. 2023

Preprint

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PurposeWe conducted a clinical study to characterize fine spatiotemporal alterations of FEM in controls and patients with pre-clinical signs of age-related macular degeneration (AMD).MethodsTwenty-seven participants were recruited from the SilverSight cohort of the Vision Institute - Quinze-Vingts National Vision Hospital, Paris. Subjects were included in three groups: healthy young, healthy aging controls, and aging subjects with drusen. Detection of microdrusen was done using gaze-dependent adaptive optics ophthalmology. Monocular retinal tracking was based on adaptive optics flood illumination ophthalmoscopy (AO-FIO). The system allows for sub-arcminute resolution, high-speed, distortion-free imaging of the foveal area. Local stimulation through digital micromirror (DMD) projection from a near infrared source enabled projection of optotypes. Eye movements were estimated using a phase-correlation registration algorithm.ResultsCompared to controls, patients with foveal drusen showed higher microsaccade amplitude, higher drift diffusion coefficient, and worse fixation stability -i.e. higher isoline area. Among the drusen group, the increase of microsaccade amplitude and ISOA was correlated with drusen eccentricity; the closer the drusen were to the center of the fovea, the more unstable were FEM.ConclusionsWe demonstrate the clinical interest of a novel high-precision retinal tracking technique to characterize FEM changes at the microscopic level. We found significant differences between the drusen group and both healthy young and older adult groups. Central drusen altered fixation stability characteristics, resulting in compensatory FEM changes. High speed, high resolution FEM analysis may help to define the functional signatures of early age-related changes.

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Fixational eye movements in passive versus active sustained fixation tasks

Cited by 26 publications

References 66 publications

Fixational eye movements as active sensation for high visual acuity

Fixational eye movements as active sensation for high visual acuity

Impact of Reference Center Choice on Adaptive Optics Imaging Cone Mosaic Analysis

Foveolar drusen decrease fixation stability in pre-symptomatic AMD

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