scholarly journals Presaccadic attention enhances contrast sensitivity, but not at the upper vertical meridian

2021 ◽  
Author(s):  
Nina M Hanning ◽  
Marc M Himmelberg ◽  
Marisa Carrasco
Keyword(s):  
Contrast Sensitivity ◽  
Head Rotation ◽  
Visual Performance ◽  
Covert Attention ◽  
Attentional Orienting ◽  
Endogenous Attention ◽  
Vertical Meridian ◽  
Eye Fixation ◽  
Neural Computations ◽  
Saccade Preparation

Human visual performance is not only better at the fovea and decreases with eccentricity, but also has striking radial asymmetries around the visual field: At a fixed eccentricity, it is better along (1) the horizontal than vertical meridian and (2) the lower than upper vertical meridian. These asymmetries, known as performance fields, are pervasive -they emerge for many visual dimensions, regardless of head rotation, stimulus orientation or display luminance- and resilient -they are not alleviated by covert exogenous or endogenous attention, deployed in the absence of eye movements. Performance fields have been studied exclusively during eye fixation. However, a major driver of everyday attentional orienting is saccade preparation, during which visual attention automatically shifts to the future eye fixation. This presaccadic shift of attention is considered strong and compulsory, and relies on fundamentally different neural computations and substrates than covert attention. Given these differences, we investigated whether presaccadic attention can compensate for the ubiquitous performance asymmetries observed during eye fixation. Our data replicate polar performance asymmetries during fixation and document the same asymmetries during saccade preparation. Crucially, however, presaccadic attention enhanced contrast sensitivity at the horizontal and lower vertical meridian, but not at the upper vertical meridian. Thus, instead of attenuating polar performance asymmetries, presaccadic attention exacerbates them.

scholarly journals Stimulus-dependent contrast sensitivity asymmetries around the visual field

2020 ◽  
Author(s):  
Marc M. Himmelberg ◽  
Jonathan Winawer ◽  
Marisa Carrasco
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Visual Angle ◽  
Individual Variability ◽  
Visual Performance ◽  
Orientation Discrimination ◽  
Stimulus Parameter ◽  
Vertical Meridian ◽  
Visual Tasks ◽  
Systematic Manipulation

AbstractAsymmetries in visual performance at isoeccentric locations are known as performance fields. At a fixed eccentricity, visual performance is best along the horizontal, intermediate along the lower vertical, and poorest along the upper vertical meridian. These performance fields are pervasive across a range of visual tasks, including those mediated by contrast sensitivity. However, contrast performance fields have not been characterized with a systematic manipulation of stimulus spatial frequency, eccentricity, and size; three parameters that constrain contrast sensitivity. Further, individual differences in performance fields measurements have not been assessed. Here, we use an orientation discrimination task to characterize the pattern of contrast sensitivity across four isoeccentric locations along the cardinal meridians, and to examine whether and how this asymmetry pattern changes with systematic manipulation of stimulus spatial frequency (4 cpd to 8 cpd), eccentricity (4.5° to 9°), and size (3° visual angle to 6° visual angle). Our data demonstrate that contrast sensitivity is highest along the horizontal, intermediate along the lower vertical, and poorest along the upper vertical meridian. This pattern is consistent across stimulus parameter manipulations, even though they cause profound shifts in contrast sensitivity. Eccentricity-dependent decreases in contrast sensitivity can be compensated for by scaling stimulus size alone. Moreover, we find that individual variability in the strength of performance field asymmetries is consistent across conditions. This study is the first to systematically and jointly manipulate, and compare, contrast performance fields across spatial frequency, eccentricity, and size, and to address individual variability in performance fields.

scholarly journals Visual performance in a flight simulator: multifocal intraocular lenses in pilots

2018 ◽  
Vol 3 (1) ◽  
pp. e000139
Author(s):  
Lee Lenton
Keyword(s):  
Visual Acuity ◽  
Contrast Sensitivity ◽  
Luminance Contrast ◽  
Intraocular Lenses ◽  
Visual Performance ◽  
Flight Simulator ◽  
Night Time ◽  
Multifocal Intraocular Lenses ◽  
Low Luminance ◽  
Visual Tasks

ObjectiveTo compare the performance of adults with multifocal intraocular lenses (MIOLs) in a realistic flight simulator with age-matched adults with monofocal intraocular lenses (IOLs).Methods and AnalysisTwenty-five adults ≥60 years with either bilateral MIOL or bilateral IOL implantation were enrolled. Visual function tests included visual acuity and contrast sensitivity under photopic and mesopic conditions, defocus curves and low luminance contrast sensitivity tests in the presence and absence of glare (Mesotest II), as well as halo size measurement using an app-based halometer (Aston halometer). Flight simulator performance was assessed in a fixed-based flight simulator (PS4.5). Subjects completed three simulated landing runs in both daytime and night-time conditions in a randomised order, including a series of visual tasks critical for safety.ResultsOf the 25 age-matched enrolled subjects, 13 had bilateral MIOLs and 12 had bilateral IOLs. Photopic and mesopic visual acuity or contrast sensitivity were not significantly different between the groups. Larger halo areas were seen in the MIOL group and Mesotest values were significantly worse in the MIOL group, both with and without glare. The defocus curves showed better uncorrected visual acuity at intermediate and near distances for the MIOL group. There were no significant differences regarding performance of the vision-related flight simulator tasks between both groups.ConclusionsThe performance of visually related flight simulator tasks was not significantly impaired in older adults with MIOLs compared with age-matched adults with monofocal IOLs. These findings suggest that MIOLs do not impair visual performance in a flight simulator.

Visual performance and patient satisfaction following the implantation of a novel trifocal supplementary intraocular lens

2020 ◽  
pp. 112067212096904
Author(s):  
Sinan Albayrak ◽  
Özge Begüm Comba ◽  
Muharrem Karakaya
Keyword(s):  
Patient Satisfaction ◽  
Contrast Sensitivity ◽  
Intraocular Lens ◽  
Visual Performance ◽  
Near Vision ◽  
Refractive Outcomes ◽  
Effective Option ◽  
Lens Surgery ◽  
Capsular Bag ◽  
Iol Dislocation

Purpose: To evaluate the visual quality, visual performance, and patient satisfaction after the implantation of the last generation supplementary intraocular lens (1stQ AddOn Trifocal) for achieving near vision spectacle-independence in pseudophakic patients who had primary monofocal capsular bag implantation. Methods: Patients who underwent monofocal lens surgery in the past year, and who expressed their explicit desire to become spectacle-independent were included in this prospective observational study. Uncorrected and corrected distance, intermediate and near visual acuities (CDVA, UDVA, DCIVA, UIVA, CNVA, and UNVA), refractive outcomes, lens positioning, contrast sensitivity and patient satisfaction were assessed 6 months postoperatively. Results: About 28 eyes of 18 patients were evaluated. No intra- or postoperative complications (iris chafing, iris capture, interlenticular opacification, IOL-dislocation, etc.) could be observed. The postoperative mean UDVA and CDVA were 0.05 ± 0.08 and 0.01 ± 0.03 (logMAR), respectively. The mean UNVA improved from the preoperative 0.50 ± 0.23 to 0.02 ± 0.05 (logMAR), postoperatively ( p = 0.0104). The postoperative mean UIVA and DCIVA were 0.06 ± 0.020 and 0.01 ± 0.00 (logMAR), respectively. Twenty-five eyes (89%) had a residual spherical equivalent within 1.0 D from the target refraction, emmetropia. Contrast sensitivity measured in photopic and mesopic conditions were statistically indifferent from the preoperative curves. All patients had better visual function and quality scores compared to the preoperative responses. The highest improvement could be achieved in near vision activities, dependency, and limitation of social functioning. Conclusion: The 1stQ AddOn Trifocal lens represents a safe and effective option for pseudophakic patients aiming for high quality, spectacle-free vision.

Contrast sensitivity assessment using the visual performance tester

2000 ◽  
Vol 26 (6) ◽  
pp. 806-809 ◽  
Author(s):  
Carlos Argento ◽  
Maria José Cosentino ◽  
Edgar Rodriguez
Keyword(s):  
Contrast Sensitivity ◽  
Visual Performance ◽  
Sensitivity Assessment

scholarly journals The effect of offset cues on saccade programming and covert attention

2018 ◽  
Vol 72 (3) ◽  
pp. 481-490 ◽  
Author(s):  
Daniel T Smith ◽  
Soazig Casteau
Keyword(s):  
Reaction Times ◽  
Motor Preparation ◽  
Covert Attention ◽  
Oculomotor Control ◽  
Covert Orienting ◽  
Cueing Task ◽  
Tightly Coupled ◽  
Saccade Programming ◽  
Saccadic Reaction Times ◽  
Saccade Preparation

Salient peripheral events trigger fast, “exogenous” covert orienting. The influential premotor theory of attention argues that covert orienting of attention depends upon planned but unexecuted eye-movements. One problem with this theory is that salient peripheral events, such as offsets, appear to summon attention when used to measure covert attention (e.g., the Posner cueing task) but appear not to elicit oculomotor preparation in tasks that require overt orienting (e.g., the remote distractor paradigm). Here, we examined the effects of peripheral offsets on covert attention and saccade preparation. Experiment 1 suggested that transient offsets summoned attention in a manual detection task without triggering motor preparation planning in a saccadic localisation task, although there were a high proportion of saccadic capture errors on “no-target” trials, where a cue was presented but no target appeared. In Experiment 2, “no-target” trials were removed. Here, transient offsets produced both attentional facilitation and faster saccadic responses on valid cue trials. A third experiment showed that the permanent disappearance of an object also elicited attentional facilitation and faster saccadic reaction times. These experiments demonstrate that offsets trigger both saccade programming and covert attentional orienting, consistent with the idea that exogenous, covert orienting is tightly coupled with oculomotor activation. The finding that no-go trials attenuates oculomotor priming effects offers a way to reconcile the current findings with previous claims of a dissociation between covert attention and oculomotor control in paradigms that utilise a high proportion of catch trials.

scholarly journals Visual Outcomes, Quality of Vision, and Quality of Life of Diffractive Multifocal Intraocular Lens Implantation after Myopic Laser In Situ Keratomileusis: A Prospective, Observational Case Series

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
John S. M. Chang ◽  
Jack C. M. Ng ◽  
Vincent K. C. Chan ◽  
Antony K. P. Law
Keyword(s):  
Quality Of Life ◽  
Contrast Sensitivity ◽  
Intraocular Lens ◽  
Case Series ◽  
Visual Performance ◽  
Laser In Situ Keratomileusis ◽  
Life Questionnaire ◽  
Multifocal Intraocular Lens

Purpose. To report visual performance and quality of life after implantation of a bifocal diffractive multifocal intraocular lens (MIOL) in postmyopic laser in situ keratomileusis (LASIK) patients.Methods. Prospective, observational case series. Patients with prior myopic LASIK who had implantation of Tecnis ZMA00/ZMB00 MIOL (Abbott Medical Optics) at Hong Kong Sanatorium and Hospital were included. Postoperative examinations included monocular and binocular distance, intermediate and near visual acuity (VA), and contrast sensitivity; visual symptoms (0–5); satisfaction (1–5); spectacle independence rate; and quality of life.Results. Twenty-three patients (27 eyes) were included. No intraoperative complications developed. Mean monocular uncorrected VA at distance, intermediate, and near were0.13±0.15(standard deviation),0.22±0.15, and0.16±0.15, respectively. Corresponding mean values for binocular uncorrected VA were0.00±0.10,0.08±0.13, and0.13±0.10, respectively. No eyes lost >1 line of corrected distance VA. Contrast sensitivity at different spatial frequencies between operated and unoperated eyes did not differ significantly (allP>0.05). Mean score for halos, night glare, starbursts, and satisfaction were1.46±1.62,1.85±1.69,0.78±1.31, and3.50±1.02, respectively. Eighteen patients (78%) reported complete spectacle independence. Mean composite score of the quality-of-life questionnaire was90.31±8.50out of 100.Conclusions. Implantation of the MIOL after myopic LASIK was safe and achieved good visual performance.

scholarly journals Semantic Influences on Overt and Covert Visual Attention

2021 ◽  
Author(s):  
◽  
Matthew David Weaver
Keyword(s):  
Visual Attention ◽  
Visual Information ◽  
Semantic Information ◽  
Past Research ◽  
Covert Attention ◽  
Attentional Orienting ◽  
Covert Visual Attention ◽  
Visual Orienting ◽  
Attentional System ◽  
Series Of Experiments

<p>People are constantly confronted by a barrage of visual information. Visual attention is the crucial mechanism which selects for further processing, subsets of information which are most behaviourally relevant, allowing us to function effectively within our everyday environment. This thesis explored how semantic information (i.e., information which has meaning) encountered within the environment influences the selective orienting of visual attention. Past research has shown semantic information does affect the orienting of attention, but the processes by which it does so remain unclear. The extent of semantic influence on the visual attention system was determined by parsing visual orienting into the tractable components of covert and overt orienting, and capture and hold process stages therein. This thesis consisted of a series of experiments which were designed, utilising well- established paradigms and semantic manipulations in concert with eye-tracking techniques, to test whether the capture and hold of either overt or covert forms of visual attention were influenced by semantic information. Taking together the main findings across all experiments, the following conclusions were drawn. 1) Semantic information differentially influences covert and overt attentional orienting processes. 2) The capture and hold of covert attention is generally uninfluenced by semantic information. 3) Semantic information briefly encountered in the environment can facilitate or prime action independent of covert attentional orienting.4) Overt attention can be both preferentially captured and held by semantically salient information encountered in visual environments. The visual attentional system thus appears to have a complex relationship with semantic information encountered in the visual environment. Semantic information has a differential influence on selective orienting processes that depends on the form of orienting employed and a range of circumstances under which attentional selection takes place.</p>

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