scholarly journals Spatial summation in the human fovea: Do normal optical aberrations and fixational eye movements have an effect?

2018 ◽  
Vol 18 (8) ◽  
pp. 6 ◽  
Author(s):  
William S. Tuten ◽  
Robert F. Cooper ◽  
Pavan Tiruveedhula ◽  
Alfredo Dubra ◽  
Austin Roorda ◽  
...  
Keyword(s):  
Eye Movements ◽  
Spatial Summation ◽  
Optical Aberrations ◽  
Fixational Eye Movements

scholarly journals Spatial summation in the human fovea: the effect of optical aberrations and fixational eye movements

2018 ◽  
Author(s):  
William S. Tuten ◽  
Robert F. Cooper ◽  
Pavan Tiruveedhula ◽  
Alfredo Dubra ◽  
Austin Roorda ◽  
...  
Keyword(s):  
Eye Movements ◽  
Visual System ◽  
Adaptive Optics ◽  
Ganglion Cells ◽  
Spatial Summation ◽  
Spatial Vision ◽  
Optical Aberrations ◽  
Stimulus Motion ◽  
Fixational Eye Movements ◽  
Magnocellular Visual Pathway

AbstractPsychophysical inferences about the neural mechanisms supporting spatial vision can be undermined by uncertainties introduced by optical aberrations and fixational eye movements, particularly in fovea where the neuronal grain of the visual system is fine. We examined the effect of these pre-neural factors on photopic spatial summation in the human fovea using a custom adaptive optics scanning light ophthalmoscope that provided control over optical aberrations and retinal stimulus motion. Consistent with previous results, Ricco’s area of complete summation encompassed multiple photoreceptors when measured with ordinary amounts of ocular aberrations and retinal stimulus motion. When both factors were minimized experimentally, summation areas were essentially unchanged, suggesting that foveal spatial summation is limited by post-receptoral neural pooling. We compared our behavioral data to predictions generated with a physiologically-inspired front-end model of the visual system, and were able to capture the shape of the summation curves obtained with and without pre-retinal factors using a single post-receptoral summing filter of fixed spatial extent. Given our data and modeling, neurons in the magnocellular visual pathway, such as parasol ganglion cells, provide a candidate neural correlate of Ricco’s area in the central fovea.

scholarly journals Fixation eye movement abnormalities and stereopsis recovery following strabismus repair

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Talora L. Martin ◽  
Jordan Murray ◽  
Kiran Garg ◽  
Charles Gallagher ◽  
Aasef G. Shaikh ◽  
...  
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Functional Improvement ◽  
Slow Phase ◽  
Fixational Eye Movements ◽  
Movement Characteristics ◽  
Adaptive Mechanisms ◽  
Before And After ◽  
Gaze Holding ◽  
Fixational Saccades

AbstractWe evaluated the effects of strabismus repair on fixational eye movements (FEMs) and stereopsis recovery in patients with fusion maldevelopment nystagmus (FMN) and patients without nystagmus. Twenty-one patients with strabismus, twelve with FMN and nine without nystagmus, were tested before and after strabismus repair. Eye-movements were recorded during a gaze-holding task under monocular viewing conditions. Fast (fixational saccades and quick phases of nystagmus) and slow (inter-saccadic drifts and slow phases of nystagmus) FEMs and bivariate contour ellipse area (BCEA) were analyzed in the viewing and non-viewing eye. Strabismus repair improved the angle of strabismus in subjects with and without FMN, however patients without nystagmus were more likely to have improvement in stereoacuity. The fixational saccade amplitudes and intersaccadic drift velocities in both eyes decreased after strabismus repair in subjects without nystagmus. The slow phase velocities were higher in patients with FMN compared to inter-saccadic drifts in patients without nystagmus. There was no change in the BCEA after surgery in either group. In patients without nystagmus, the improvement of the binocular function (stereopsis), as well as decreased fixational saccade amplitude and intersaccadic drift velocity, could be due, at least partially, to central adaptive mechanisms rendered possible by surgical realignment of the eyes. The absence of improvement in patients with FMN post strabismus repair likely suggests the lack of such adaptive mechanisms in patients with early onset infantile strabismus. Assessment of fixation eye movement characteristics can be a useful tool to predict functional improvement post strabismus repair.

scholarly journals Control and coordination of fixational eye movements in the Snellen acuity test

2019 ◽  
Vol 19 (10) ◽  
pp. 145a
Author(s):  
Janis Intoy ◽  
Michele A Cox ◽  
Michele Rucci
Keyword(s):  
Eye Movements ◽  
Fixational Eye Movements ◽  
Snellen Acuity ◽  
Acuity Test

scholarly journals What is the best fixation target? The effect of target shape on stability of fixational eye movements

2013 ◽  
Vol 76 ◽  
pp. 31-42 ◽  
Author(s):  
L. Thaler ◽  
A.C. Schütz ◽  
M.A. Goodale ◽  
K.R. Gegenfurtner
Keyword(s):  
Eye Movements ◽  
Fixation Target ◽  
Target Shape ◽  
Fixational Eye Movements

Eye Position Compensation Improves Estimates of Response Magnitude and Receptive Field Geometry in Alert Monkeys

2007 ◽  
Vol 97 (5) ◽  
pp. 3439-3448 ◽  
Author(s):  
Yamei Tang ◽  
Alan Saul ◽  
Moshe Gur ◽  
Stephanie Goei ◽  
Elsie Wong ◽  
...  
Keyword(s):  
Eye Movements ◽  
Receptive Field ◽  
Receptive Fields ◽  
Eye Position ◽  
Stimulus Position ◽  
Fixational Eye Movements ◽  
Field Geometry ◽  
Receptive Field Subregions ◽  
Movement Compensation ◽  
Definition Of

Studies of visual function in behaving subjects require that stimuli be positioned reliably on the retina in the presence of eye movements. Fixational eye movements scatter stimuli about the retina, inflating estimates of receptive field dimensions, reducing estimates of peak responses, and blurring maps of receptive field subregions. Scleral search coils are frequently used to measure eye position, but their utility for correcting the effects of fixational eye movements on receptive field maps has been questioned. Using eye coils sutured to the sclera and preamplifiers configured to minimize cable artifacts, we reexamined this issue in two rhesus monkeys. During repeated fixation trials, the eye position signal was used to adjust the stimulus position, compensating for eye movements and correcting the stimulus position to place it at the desired location on the retina. Estimates of response magnitudes and receptive field characteristics in V1 and in LGN were obtained in both compensated and uncompensated conditions. Receptive fields were narrower, with steeper borders, and response amplitudes were higher when eye movement compensation was used. In sum, compensating for eye movements facilitated more precise definition of the receptive field. We also monitored horizontal vergence over long sequences of fixation trials and found the variability to be low, as expected for this precise behavior. Our results imply that eye coil signals can be highly accurate and useful for optimizing visual physiology when rigorous precautions are observed.

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