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Purpose: Age‐related nonparalytic hypertropia (ARNH) is reported to be involved in sagging eye syndrome, where excyclotorsion is large and the lower eye is more extorted. The primary aim of this study was to describe the clinical profiles of patients with ARNH. The secondary aim was to compare cyclotorsion in patients with ARNH with that in normal individuals. Methods: Inclusion criteria for ARNH were insidious onset of diplopia at distance after 50 years of age, nonparalytic hyperdeviation and follow‐up >6 months. Objective cyclotorsion was measured as the disc‐to‐fovea angle (DFA) on fundus photographs obtained from two groups: 75 patients with ARNH (age, 74.1 ± 7.9 years) and 75 sex‐ and age‐matched normal controls (73.9 ± 8.1 years). Results: The hypertropia angle was 4.6 ± 2.8 prism dioptres. One patient also experienced diplopia at near‐gaze. DFA in ARNH (right/left eye; 11.0 ± 4.8°/11.6 ± 3.9°) was larger than that of the control (6.6 ± 3.7°/9.2 ± 3.5°) (p < 0.0001). The DFA in the non‐dominant eye (12.5 ± 4.1°) was larger than that in the dominant eye (10.2 ± 4.3°) (p = 0.0003). The lower eye did not have the larger DFA in 29 patients. Conclusion: The angle of hyperdeviation in patients with ARNH was small. The DFA in the ARNH group was larger than that in the normal group. The lower eye was not the eye with a larger DFA in 39% of ARNH, inconsistent with sagging eye syndrome. Decreased phoria adaptation (fusional ability) may trigger diplopia in patients with ARNH. [ABSTRACT FROM AUTHOR]

To investigate the reliability (internal consistency) of a Combined Foot and Eye Dominance Scale in healthy subjects.

The aim of the study was to analyze the stability of dominant and non-dominant eye fixations, as well as the influence of development on fixation stability. The study analyzed fixation stability in 280 school-age children, ranging in age from 7 to 12 years old. Fixation stability was determined by calculating the bivariate contour ellipse area (BCEA). During the fixation task, eye movements were recorded using the Tobii Pro Fusion eye tracking device at a 250 Hz sampling frequency. The results indicate that the fixation stability of dominant and non-dominant eyes, as well as the fixation stability of each eye regardless of dominance, improves as children grow older. It was found that for 7 and 8-year-old children, fixation in the dominant eye is significantly more stable than in the non-dominant eye, while in older children, there is no significant difference in fixation stability between the dominant and non-dominant eye.

Background: To investigate the frequency of left eye dominance and minor physical anomalies (MPAs) in schizophrenia patients and control subjects and determine the interrelations of these two biological markers of neuronal dysontogenesis in schizophrenia. Subjects and methods: Three tests for eye dominance were administered as performance tasks, not preference questionnaires. Seven MPAs were examined. The sample consisted of 180 (98 schizophrenia patients and 82 control subjects). Several statistical methods for examining the eye tests separately and together were used to assess the difference in left-eyedness between schizophrenia patients and control subjects. Results: Left eye dominance is significantly higher in schizophrenia subjects. Left-eyed subjects are more stigmatized with MPAs. There is a strong positive correlation between left-eyedness and stigmatization with MPAs in schizophrenia patients. Conclusion: As hand dominance is under cultural pressure, eye dominance is culturally independent and is useful and reliable indicator of altered hemispheric lateralization. The significant positive correlations between left-eyedness and MPAs and the high concurrence of these biological markers in schizophrenia patients are a potent indicator of underlying aberrant neurodevelopment. [ABSTRACT FROM AUTHOR]

Background and Objective: Reaction time measures have considerable potential to aid neuropsychological assessment in a variety of healthcare settings. One such measure, the intra-individual reaction time variability is of particular interest as it is thought to reflect neurobiological disturbance. The present study aimed to investigate the intra-individual changes in reaction time to visual stimuli in dominant or non-dominant binocular and monocular vision. Methods: This descriptive-analytical study was conducted on 12 volunteers with an average age of 30.08±1.448 years in 2021. The subjects consisted of the students and staff of Golestan University of Medical Sciences (5 female and 7 male). The reaction time was recorded automatically by the hand reaction time device of Danesh Salar Iranian Company based on the time of presentation of visual stimulation on the computer screen and the person's reaction, i.e. pressing the buttons of the handles by each of the two hands. All experiments were performed between 10 and 11 am and following at least 2 hours of fasting. Data collection was done following training trials for correct performance of the 2-choice reaction time test. After completing the reaction time tests for each volunteer, the dominant eye was determined by the hole-in-card method. Results: In 4 volunteers, the dominant eye was left and in the rest of the volunteers, the dominant eye was right. The dominant eye did not differ between men and women. The number of reaction times recorded in right monocular vision left monocular vision and binocular vision were 902, 911 and 893, respectively. The mean reaction time in right monocular vision, left monocular vision and binocular vision was 306.81±3.310, 304.28±3.339 and 312.95±4.569, respectively, and the range of reaction times in these three states was between 194-1750, 178-1587, and 155-1797 ms, respectively. Intra-individual reaction time variability in the dominant left eye and left hand were significantly lower compared to the dominant right eye and right hand, respectively (P

BackgroundTo investigate the frequency of left eye dominance and minor physical anomalies (MPAs) in schizophrenia patients and control subjects and determine the interrelations of these two biological markers of neuronal dysontogenesis in schizophrenia.Subjects and methodsThree tests for eye dominance were administered as performance tasks, not preference questionnaires. Seven MPAs were examined. The sample consisted of 180 (98 schizophrenia patients and 82 control subjects). Several statistical methods for examining the eye tests separately and together were used to assess the difference in left-eyedness between schizophrenia patients and control subjects.ResultsLeft eye dominance is significantly higher in schizophrenia subjects. Left-eyed subjects are more stigmatized with MPAs. There is a strong positive correlation between left-eyedness and stigmatization with MPAs in schizophrenia patients.ConclusionAs hand dominance is under cultural pressure, eye dominance is culturally independent and is useful and reliable indicator of altered hemispheric lateralization. The significant positive correlations between left-eyedness and MPAs and the high concurrence of these biological markers in schizophrenia patients are a potent indicator of underlying aberrant neurodevelopment.

• We tested activation-inhibition hypothesis of distribution of attention in space. • Lateralised cue-target pairs presented to same or opposite visual field. • Handedness affected word processing in left hemisphere due to contralateral cueing. • Eye dominance associated with interhemispheric communication. • Interacting control systems contribute to information transfer between hemispheres. Dominance of the left hemisphere for language processing is a prominent feature of brain organisation. Whereas structural models clarify the functional asymmetry due to direct access to local language circuits, dynamic models propose functional states of intrahemispheric activation and interhemispheric inhibition that are coupled with attentional processes. Real word settings often require modulations of lateralised neural processing and further express individual heterogeneity. In this research, we tested left- and right-handers, and used a behavioural paradigm with presentation of lateralised cue-target pairs to the same or opposite visual field. We observed that handedness distinctly affected word processing in the left hemisphere following contralateral cueing. Moreover, left-hemispheric dominance strengthened for right-handers vs abolished for left-handers, influencing behavioural efficiency. In combination with eye dominance recordings, these data suggest that attentional biases guided the processing strategies of both groups and in turn their achievements. Therefore, hand and eye dominance are both essential factors with a functional role in directing the communication of visual information between both hemispheres. Overall, the findings underline the importance of interacting hand-eye control systems in contributing to interhemispheric patterns in the context of language processing. [ABSTRACT FROM AUTHOR]

Background and Objective: Reaction time measures have considerable potential to aid neuropsychological assessment in a variety of healthcare settings. One such measure, the intra-individual reaction time variability is of particular interest as it is thought to reflect neurobiological disturbance. The present study aimed to investigate the intra-individual changes in reaction time to visual stimuli in dominant or non-dominant binocular and monocular vision. Methods: This descriptive-analytical study was conducted on 12 volunteers with an average age of 30.08±1.448 years in 2021. The subjects consisted of the students and staff of Golestan University of Medical Sciences (5 female and 7 male). The reaction time was recorded automatically by the hand reaction time device of Danesh Salar Iranian Company based on the time of presentation of visual stimulation on the computer screen and the person's reaction, i.e. pressing the buttons of the handles by each of the two hands. All experiments were performed between 10 and 11 am and following at least 2 hours of fasting. Data collection was done following training trials for correct performance of the 2-choice reaction time test. After completing the reaction time tests for each volunteer, the dominant eye was determined by the hole-in-card method. Results: In 4 volunteers, the dominant eye was left and in the rest of the volunteers, the dominant eye was right. The dominant eye did not differ between men and women. The number of reaction times recorded in right monocular vision left monocular vision and binocular vision were 902, 911 and 893, respectively. The mean reaction time in right monocular vision, left monocular vision and binocular vision was 306.81±3.310, 304.28±3.339 and 312.95±4.569, respectively, and the range of reaction times in these three states was between 194-1750, 178-1587, and 155-1797 ms, respectively. Intraindividual reaction time variability in the dominant left eye and left hand were significantly lower compared to the dominant right eye and right hand, respectively (P<0.05). No difference was observed between the reaction time of the right monocular vision, left monocular vision, and binocular vision. Conclusion: The alignment of the dominant left side in the eye and hand reacts faster than the dominant right side in the eye and hand. The mechanism of this phenomenon may be related to the overall process that determines the dominant left hemisphere in approximately 90% of the population. [ABSTRACT FROM AUTHOR]

Aim: To investigate the relationship of contrast sensitivity (CS) with binocularity, eye dominance, and interpupillary distance at various spatial frequencies in healthy adults. Method: Thirty-seven healthy adults (age range, 19-45 years; 27 males) were included. Binocular and monocular measurements of CS were performed with Automatize ClearChart 2 test on monocular (right and left) and both eyes at low-(1.5 cpd), mid- (6 cpd), and high- (18 cpd) spatial frequencies. Eye dominance was determined with the Hole-in-card test and interpupillary distance was measured with PlusOptics photo scanner, and the results were compared statistically. Results: Eye dominance was identified in 35 (94.59 %) subjects with the right eye being dominant in 23 (65.7%) subjects. The logarithmic CS (logCS) in the dominant eye, non-dominant eye, both eyes were 2.58±0.29, 2.62±0.37, and 2.50±0.00, respectively at 1.5 cpd; 2.54±0.16, 2.50±0.00, and 2.50±0.00, respectively at 6 cpd; and 5.46±2.49, 5.26±2.61, and 3.82±1.82, respectively at 18 cpd. The logCS did not significantly differ between dominant and non-dominant eyes. Binocular logCS was lower than monocular logCS significantly at 18 cpd (p=0.001). The interpupillary distance (mean, 58.78±3.63 mm) was not correlated with binocular logCS. Conclusions: Dominant eye was similar to non-dominant eye in terms of CS function at all frequencies in healthy adults. No functional relationship was detected between interpupillary distance and binocular CS. Binocular CS function showed individual differences at high-spatial frequency in healthy adults. [ABSTRACT FROM AUTHOR]

It has been argued that dyslexia may develop in strongly left eye dominant children through learning to write using ipsilateral, right hemisphere motor pathways. New light on this theory has been cast by recent findings of atypical enhanced corpus callosum white matter in children with dyslexia, reflecting right to left hemisphere communication that is resistant to intensive remedial reading intervention. Enhanced corpus callosum white matter is consistent with uninhibited right to left hemisphere ipsilateral mirror-motor innervation, manifested as frequent mirror-letter writing errors in children with dyslexia. Delaying writing instruction until 7–8 years of age may prevent these errors and as well as the development of dyslexia. During the 7–8-year age period, visual-proprioceptive integration enables a child to mentally map whole word visual images onto kinesthetic/proprioceptive letter engrams (memory representations). Hypothetically, this process is facilitated by anterior commissure activity involving interhemispheric transfer of ipsilateral mirror-to-non mirror-motor movement. This postulate, involving delayed writing instruction pending further maturation, also receives indirect support from the remarkable proficiency leap among second graders reading Hebrew as Hebrew involves a leftward orthography in which ipsilateral right to left hemisphere innervation is uninhibited. Additionally, and more directly, normal reading comprehension for learning English among children with agenesis of the corpus callosum suggests that letter-sound decoding is not the sole route to proficient reading comprehension. In this paper, I make recommendations for obtaining empirical evidence of premature writing as a cause of dyslexia. [ABSTRACT FROM AUTHOR]

Background: Schizophrenia is a chronic brain disorder of diverse etiology and clinical presentation. Despite the expansion of treatment methods, between 30 and 50% of cases remain resistant to treatment. In patients with schizophrenia, specifics in the dominant lateralization in the brain function have been discovered. This gave a reason to seek the relation between functional lateralization and the effect of treatment. Methods: Of the 105 people observed with schizophrenia, 45 (42.9%) were treatment resistant, and 60 (57.1%) were considered responders. We compared functional lateralization (hand, foot, and eye) between the two groups. Handedness was ascertained by using the Edinburgh Handedness Inventory. The assessment was made at 12 weeks of treatment. Results: Of all patients with schizophrenia, 41.89% have mixed lateralization, 53.34% are right winged, and 4.76% of the patients are left winged. Resistance of the symptoms shows that 26 (57.78%) are cross-dominated, 18 (40%) are right winged, and 1 (2.22%) is left winged. In patients with clinical remission, 18 (30%) are of mixed dominance, 38 (63.33%) are right winged, and 4 (6.66%) are left winged. From the results for the separate lateralization of the hand, foot, and eye, we found a significant difference only in terms of the dominance of the eye. In 44 (41.9%) of the patients, we found dominance of the left eye. In patients with resistance, the percentage established by us is higher—at 26 (57.8%). These results indicate that the increased percentage of mixed dominance in patients with schizophrenia is mainly due to left-sided lateralization of the eye, especially in those with resistance to treatment. Conclusion: We find an increased number of patients with cross-dominance left eye dominance in patients with schizophrenia. Cross-dominance and left eye dominance are associated with a higher probability of symptom resistance than other forms of lateralization (left-handed or right-handed). The high percentage of cross-dominance is due to the high percentage of left-sided dominance of the eye. [ABSTRACT FROM AUTHOR]

Steven Brown,1 Clayton Rue,2 Kyle Smith,3 Robert Arnold4 1Martin Methodist University, Pulaski, TN, USA; 2NSCA Level III Instructor, Anchorage, AK, USA; 3Accurate Vision, Anchorage, AK, USA; 4Alaska Blind Child Discovery, Alaska Children’s EYE & Strabismus, Anchorage, AK, USACorrespondence: Robert ArnoldThe Alaska Blind Child Discovery, Alaska Children’s EYE & Strabismus, 3500 Latouche #280, Anchorage, AK, 99508, USATel +1 (907)561-1917Fax +1 (907)563-5373Email eyedoc@alaska.netBackground: Conventional near and stereo tests have a “floor effect;” inability to discriminate normal from super-normal. Shotgun champions require unique performance in binocularity and rapid color discrimination.Patients and Methods: Twenty-nine champion clay-target shooters, 14 normal Army and 12 color-normal subjects were tested with conventional near vision tests and on PDI-Check, a series of dynamic, near vision tests on the autostereoscopic Nintendo console.Results: Conventional tested shotgunners had all perfect Ishihara and 75% best 40 sec Stereo fly while Army had 92%perfect Ishihara and 69% best stereo fly. On PDI-Check, experienced shotgunners with median stereo of 17 (IQR 12– 41) arc sec were better than Army volunteers 59 (IQR 30 to 487) arc seconds (Mann–Whitney U=62, p=0.04). Median PDI-Check for shotgun compared to Army was 88% compared to 84% for blue cone, 90% compared to 84% for green and 77% compared to 72% (red, Mann–Whitney p=0.05). Adding dark cherry filter shooting glasses improved the red and green color detection (p< 0.01). This study lacked power to detect eye dominance using PDI Check color or stereo.Conclusion: Many champion shotgun shooters had outstanding dynamic near stereo and better-than-average color vision which could be optimized with dark filter spectacles for red and green hues. PDI Check not only helps identify abnormal binocularity and color vision, but it can clarify supranormal vision as well.Keywords: stereopsis, eye dominance, color vision

Brief periods of monocular deprivation significantly modify binocular visual processing. For example, patching one eye for a few hours alters the inter-ocular balance, with the previously patched eye becoming dominant once the patch is removed. However, the contribution of higher-level visual processing to this phenomenon is still unclear. Here, we compared changes in sensory eye dominance produced by three types of monocular manipulations in adult participants with normal binocular vision. One eye was covered for 150 min using either an opaque patch, a diffusing lens, or a prism that inverted the image. All three manipulations altered dominance duration and predominance during binocular rivalry (BR) in favour of the treated eye and the time courses of the changes were similar. These results indicate that modifications of luminance or contrast are not strictly necessary to drive shifts in eye dominance, as both were unaltered in the prism condition. Next, we found that shifts in eye dominance were dependent on attentional demands during the monocular treatment period, providing support for the role of attentional eye selection in modulating eye dominance. Finally, we found relatively rapid build-up of the ocular dominance shift after the onset of monocular treatment. Taken together, our results suggest that modifications to monocular input alter inter-ocular balance via selective attentional mechanisms that bias output towards the deprived eye. Eye-based attention may play an important role in conditions where normal input to one eye is disrupted, such as childhood amblyopia. [ABSTRACT FROM AUTHOR]

Purpose: To study the effect of eye dominance on excyclotorsion in unilateral superior oblique palsy (USOP). Study design: Retrospective clinical study Methods: Objective excyclotorsion was measured as the disc-to-fovea angle by fundus photography OU. Subjective excyclotorsion was determined with a major amblyoscope based on the difference in the earth vertical and subjective visual vertical. Eye dominance was determined by the hole-in-the-card method. A p-value ≤ 0.05 was considered statistically significant. Subjects: Data of 24 USOP patients were retrospectively collected. The diagnosis was mainly made by the Parks 3-step method, history and the presence of characteristic excyclotorsion. When possible, orbital magnetic resonance imaging findings were obtained. Results: The median angle of objective excyclotorsion in the paretic eyes was significantly larger than in the nonparetic eyes. Both median angles of objective/subjective excyclotorsion in the dominant eye were significantly smaller than those of the non-dominant eye. Patients were subdivided into two groups: group A, those whose paretic eye was the dominant eye (n = 13); group B, those whose paretic eye was the non-dominant eye (n = 11). The objective/subjective excyclotorsional angles of the paretic eye were significantly larger than of the non-paretic eye only in group B. Conclusion: In USOP the angle of excyclotorsion in the dominant eye is smaller than in the non-dominant eye. This may imply that the vertical sense of visual space is mainly adapted to the dominant eye, keeping the subjective vertical close to the earth vertical. [ABSTRACT FROM AUTHOR]

Purpose: To determine whether there is asymmetry in the lateral rectus (LR) muscle attachment between both eyes in patients with intermittent exotropia (IXT) with a non-dominant eye, but without amblyopia or anisometropia. Methods: In total, 109 patients who underwent bilateral lateral rectus recession for IXT were included, 81 with and 28 without eye dominance. The limbus-insertion distance and tendon width of the LR muscle were measured intraoperatively using callipers. The insertion-equator distance (presumed arc of contact), area of contact (arc of contact × tendon width), and torque value (radius of globe × arc of contact) of the LR muscle were calculated based on intraoperative measurements and axial length measured using a partial interferometer. Parameters regarding LR muscle attachment were compared between fellow eyes and between groups. Results: Mean measurements in all parameters related to LR muscle attachments other than tendon width were not different between the two eyes or between groups. The mean tendon width of the non-dominant eye was 9.2 ± 0.7 mm, narrower than the 9.4 ± 0.5 mm width in either eye of patients without dominance (p = 0.020). However, there was no difference in all parameters in 21 pairs of patients after matching. The proportion of patients who showed binocular discrepancies in attachment measurements beyond that attributable to potential measuring errors did not differ between the two groups. Conclusions: Structural parameters related to LR muscle attachments did not differ based on eye dominance, suggesting that the anatomic structure of LR muscle attachments is not responsible for eye dominance in IXT. [ABSTRACT FROM AUTHOR]

The adult visual system was traditionally thought to be relatively hard-wired, but recent studies have challenged this view by demonstrating plasticity following short-term monocular deprivation. Depriving one eye of spatial information for 2-3 h increased subsequent sensory dominance of that eye. However, the mechanism underlying this phenomenon is unclear. The present study sought to address this issue and determine the consequences of short-term monocular deprivation on inter-ocular suppression of each eye. Sensory eye dominance was examined before and after depriving an eye of all input using an opaque patch for 2.5 h, in six adult participants with normal binocular vision. We used a percept tracking task during binocular rivalry (BR) to assess the relative eye dominance, and an objective probe detection task under continuous flash suppression (CFS) to quantify each eye's susceptibility to inter-ocular suppression. The monocular contrast increment threshold of each eye was also measured using the probe task to ascertain if the altered eye dominance is accompanied by changes in monocular perception. Our BR results replicated previous findings of a shift of relative dominance towards the eye that has been deprived of form information. More crucially, using CFS we demonstrated reduced inter-ocular suppression of the deprived eye with no complementary changes in the other eye, and no monocular changes in increment threshold. These findings imply that short-term monocular deprivation alters binocular interactions. The differential effect on inter-ocular suppression between eyes may have important implications for the use of patching as a therapy to recover visual function in amblyopia. [ABSTRACT FROM AUTHOR]

Animals, from invertebrates to humans, stabilize the panoramic optic flow through compensatory movements of the eyes, the head or the whole body, a behavior known as optomotor response (OR). The same optic flow moved clockwise or anticlockwise elicits equivalent compensatory right or left turning movements, respectively. However, if stimulated monocularly, many animals show a unique effective direction of motion, i.e., a unidirectional OR. This phenomenon has been reported in various species from mammals to birds, reptiles, and amphibious, but among invertebrates, it has only been tested in flies, where the directional sensitivity is opposite to that found in vertebrates. Although OR has been extensively investigated in crabs, directional sensitivity has never been analyzed. Here, we present results of behavioral experiments aimed at exploring the directional sensitivity of the OR in two crab species belonging to different families: the varunid mud crab Neohelice granulata and the ocypode fiddler crab Uca uruguayensis. By using different conditions of visual perception (binocular, left or right monocular) and direction of flow field motion (clockwise, anticlockwise), we found in both species that in monocular conditions, OR is effectively displayed only with progressive (front-to-back) motion stimulation. Binocularly elicited responses were directional insensitive and significantly weaker than monocular responses. These results are coincident with those described in flies and suggest a commonality in the circuit underlying this behavior among arthropods. Additionally, we found the existence of a remarkable eye dominance for the OR, which is associated to the size of the larger claw. This is more evident in the fiddler crab where the difference between the two claws is huge.

The aim of the study was to analyze the stability of dominant and non-dominant eye fixations, as well as the influence of development on fixation stability. The study analyzed fixation stability in 280 school-age children, ranging in age from 7 to 12 years old. Fixation stability was determined by calculating the bivariate contour ellipse area (BCEA). During the fixation task, eye movements were recorded using the Tobii Pro Fusion eye tracking device at a 250 Hz sampling frequency. The results indicate that the fixation stability of dominant and non-dominant eyes, as well as the fixation stability of each eye regardless of dominance, improves as children grow older. It was found that for 7 and 8- year-old children, fixation in the dominant eye is significantly more stable than in the non-dominant eye, while in older children, there is no significant difference in fixation stability between the dominant and non-dominant eye., Competing Interests: The author(s) declare(s) that the contents of the article are in agreement with the ethics described in http://biblio.unibe.ch/portale/elibrary/BOP/jemr/ethics.html and that there is no conflict of interest regarding the publication of this paper., (Copyright (©) 2023 Evita Šerpa, Madara Alecka, Ilze Ceple, Gunta Krūmiņa, Aiga Švede, Evita Kassaliete, Viktorija Goliškina, Līva Volberga, Asnate Bērziņa, Rita Miķelsone, Anete Kļavinska, Elizabete Ozola, Daniela Toloka, Tomass Ruža, Sofija Vasiļjeva, Marija Koļeda.)

The competitive and inhibitory interactions between the two eyes' images are a pervasive aspect of binocular vision. Over the last decade, our understanding of the neural processes underpinning binocular rivalry (BR) and continuous flash suppression (CFS) has increased substantially, but we still have little understanding of the relationship between these two effects and their variation in the general population. Studies that pool data across individuals and eyes risk masking substantial variations in binocular vision that exist in the general population. To investigate this issue we compared the depth of inter-ocular suppression evoked by BR with that elicited by CFS, in a group (N = 25) of visually normal individuals. A noise pattern (either static for BR or dynamic for CFS) was presented to one eye and its suppressive influence on a probe grating presented simultaneously to the other eye was measured. We found substantial individual differences in the magnitude of suppression (a 10-fold variation in probe detection threshold) evoked by each task, but performance on BR was a significant predictor of performance on the CFS task. However many individuals showed marked asymmetries between the two eyes' ability to detect a suppressed target, that were not necessarily the same for the two tasks. There was a tendency for the magnitude of the asymmetry to increase as the refresh rate of the dynamic noise increased. The results suggest a common underlying mechanism is likely to be responsible, at least in part, for driving inter-ocular suppression under BR and CFS. The marked asymmetries in inter-ocular suppression at higher noise refresh rates, may be indicative of a difference in temporal processing between the eyes. [ABSTRACT FROM AUTHOR]

Animals, from invertebrates to humans, stabilize the panoramic optic flow through compensatory movements of the eyes, the head or the whole body, a behavior known as optomotor response (OR). The same optic flow moved clockwise or anticlockwise elicits equivalent compensatory right or left turning movements, respectively. However, if stimulated monocularly, many animals show a unique effective direction of motion, i.e., a unidirectional OR. This phenomenon has been reported in various species from mammals to birds, reptiles, and amphibious, but among invertebrates, it has only been tested in flies, where the directional sensitivity is opposite to that found in vertebrates. Although OR has been extensively investigated in crabs, directional sensitivity has never been analyzed. Here, we present results of behavioral experiments aimed at exploring the directional sensitivity of the OR in two crab species belonging to different families: the varunid mud crab Neohelice granulata and the ocypode fiddler crab Uca uruguayensis. By using different conditions of visual perception (binocular, left or right monocular) and direction of flow field motion (clockwise, anticlockwise), we found in both species that in monocular conditions, OR is effectively displayed only with progressive (front-to-back) motion stimulation. Binocularly elicited responses were directional insensitive and significantly weaker than monocular responses. These results are coincident with those described in flies and suggest a commonality in the circuit underlying this behavior among arthropods. Additionally, we found the existence of a remarkable eye dominance for the OR, which is associated to the size of the larger claw. This is more evident in the fiddler crab where the difference between the two claws is huge. [ABSTRACT FROM AUTHOR]

We analyze the role of bilateral symmetry in enhancing binocular visual ability in human eyes, and further explore how efficiently bilateral symmetry is preserved in different ocular surgical procedures. The inclusion criterion for this review was strict relevance to the clinical questions under research. Enantiomorphism has been reported in lower order aberrations, higher order aberrations and cone directionality. When contrast differs in the two eyes, binocular acuity is better than monocular acuity of the eye that receives higher contrast. Anisometropia has an uncommon occurrence in large populations. Anisometropia seen in infancy and childhood is transitory and of little consequence for the visual acuity. Binocular summation of contrast signals declines with age, independent of inter-ocular differences. The symmetric associations between the right and left eye could be explained by the symmetry in pupil offset and visual axis which is always nasal in both eyes. Binocular summation mitigates poor visual performance under low luminance conditions and strong inter-ocular disparity detrimentally affects binocular summation. Considerable symmetry of response exists in fellow eyes of patients undergoing myopic PRK and LASIK, however the method to determine whether or not symmetry is maintained consist of comparing individual terms in a variety of ad hoc ways both before and after the refractive surgery, ignoring the fact that retinal image quality for any individual is based on the sum of all terms. The analysis of bilateral symmetry should be related to the patients’ binocular vision status. The role of aberrations in monocular and binocular vision needs further investigation.

Various researches know lateral preference of eye and hand pattern as one of the important factors of performing sports skills. This study aimed at investigating the effect of lateral preference of eye and hand pattern on learning basketball free throw skill. From 3000 female students of Shahid Chamran University of Ahvaz, 60 subjects (age range 19-22 yr) were selected purposively as the sample using a researcher-made questionnaire of individual information and sporting background, Edinburgh Handedness Inventory (Oldfield, 1971) and hole card (Durand and Gold, 1910) and were assigned to two control and experimental groups (each group: 15 unilateral subjects and 15 crossed-lateral subjects). Firstly, pretest of basketball free throw was conducted. Then, practice protocol was performed for 8 weeks (24 sessions, 3 sessions a week). During this period, 6 posttests were administered to determine learning stages and one week after the last posttest, the retention test was conducted. The results showed a significant difference between unilateral and crossed-lateral (experimental group) subjects in the cognitive (sig=0.000) and associative (sig=0.000) stages of the acquisition of basketball free throw and the unilateral subjects had a better performance. Whereas there was no significant difference between unilateral and crossed-lateral subjects in the autonomous (sig=0.105) and retention (sig=0.086) stages. Finally, the results showed a difference in performance between experimental and control groups in favor of experimental group. According to these results, it seems that long practice and autonomous skill in unilateral and crossed-lateral subjects matched their performance and eliminated their differences. Therefore, coaches are recommended to identify talented subjects after a lot of practice in order to not generalize the result of performance to learning.

Objectives: The purpose of this study was to evaluate the influence of eye dominance on color perception, and shade matching., Materials and Methods: A total of 104 participants were selected for the study. There were 3 groups: Group I: 3rd and 4th year dental students and interns ( n = 40); Group II: postgraduates ( n = 34); Group III: senior residents and faculty members (≥ 6 years of clinical experience) ( n = 30). All participants were evaluated for congenital color blindness with Ishihara plates, their dominant eye with Mile's test, and their color perception with the Farnsworth-Munsell 100 hue test. The shade guide test was used for shade matching with a second corresponding set of Vitapan classical shade guides., Results: The results of Mile's test revealed that 60.6% were right-eye dominant and 39.4% were left-eye dominant. There was a statistically significant difference among all participants between the dominant eye and the non-dominant eye in shade matching., Conclusions: The dominant eye has a positive effect on shade matching and the ability to match shades becomes better with an increase in clinical experience., Competing Interests: Conflict of Interest: No potential conflict of interest relevant to this article was reported., (Copyright © 2023. The Korean Academy of Conservative Dentistry.)

The saccadic system presents asymmetries. Notably, saccadic peak velocity is higher in temporal than in nasal saccades, and in centripetal than in centrifugal saccades. It has already been shown that eye dominance strength relates to naso-temporal asymmetry, but its links with centripetal-centrifugal asymmetry has never been tested. The current study tested both naso-temporal and centripetal-centrifugal asymmetries simultaneously to provide a finer and continuous measure of eye dominance strength. We asked 63 participants to make centripetal and centrifugal saccades from five different locations. Analysis of saccadic peak velocity shows that eye dominance strength modulates every saccadic asymmetry tested. For the first time, we propose a graduated measure of eye dominance strength on a continuum model. The model ranges from weak to very strong eye dominance. Weak eye dominance corresponds to increased saccadic asymmetries whereas strong eye dominance corresponds to no asymmetries. Furthermore, our results provide new insights into the neurophysiological origins of saccadic asymmetries. Modulation of both naso-temporal and centripetal-centrifugal asymmetries by eye dominance strength supports the involvement of V1 in these saccadic asymmetries. [ABSTRACT FROM AUTHOR]

The effect of slower responses to validly than invalidly cued targets is known as inhibition of return (IOR). Opposing accounts of IOR have been proposed: one postulates a singular phenomenon explained by oculomotor mechanisms alone, while the other, more diverse account postulates both perceptual-cognitive and motor factors. In our research we considered the relation between motor programming and IOR. In an extended replication of an earlier study, using an eye abduction technique we restricted eye movement in the temporal half-space; this resulted in IOR attenuation in that area, compared to the unrestricted, nasal part of the visual field. Our results contradict the earlier result and demonstrate that IOR does depend on preparation of eye movement, as predicted by the oculomotor priming hypothesis. [ABSTRACT FROM AUTHOR]

Human eye movements are stereotyped and repeatable, but how specific to a normal individual are the quantitative properties of his or her eye movements? We recorded saccades, anti-saccades and smooth-pursuit eye movements in a sample of over 1000 healthy young adults. A randomly selected subsample (10%) of participants were re-tested on a second occasion after a median interval of 18.8days, allowing us to estimate reliabilities. Each of several derived measures, including latencies, accuracies, velocities, and left-right asymmetries, proved to be very reliable. We give normative means and distributions for each measure and describe the pattern of correlations amongst them. We identify several measures that exhibit significant sex differences. The profile of our oculomotor measures for an individual constitutes a personal oculomotor signature that distinguishes that individual from most other members of the sample of 1000. [ABSTRACT FROM AUTHOR]

The integration of hypotheses from Eye-Movement Desensitization and Reprocessing (EMDR) and Saccade Induced Retrieval Enhancement (SIRE), both of which have been met with considerable skepticism, may lead to significant gains in both domains. Cognitive accounts of EMDR, the orienting response (OR) and working memory (WM) hypotheses, and of SIRE, the interhemispheric interaction (IHI) and the top-down attentional control (TDAC) hypotheses, are discussed. The accounts show several blind spots and frictions, for instance, on re-imagining during EMs, on hemispheric lateralization, and on emotional influences of eye movements. The failure to consider these factors across and within domains may well explain the many disparate findings. This perspective aims to remove the artificial separation and seeks a theoretical integration of the domains. It combines elements of OR and TDAC into a new dopaminergic regulation hypothesis while replacing affective (i.e., positive vs. negative) by motivational mechanisms (i.e., fostering approach and recoding). EMs are posited to result in a short-latency, targeted release of dopamine, which is the central neuromodulator in approach tendencies. According to this hypothesis, the largest effects are obtained in individuals with collateralized eye dominance and dopamine dominance. Concrete suggestions are made to improve research conditions and therapeutic efficacy. • The perspective synthesizes hypotheses from EMDR and SIRE into the dopaminergic regulation hypothesis. • Eye movements elicit a dopamine signal from Superior Colliculus to Substantia Nigra. • The signal causes approach to, enhancement, and regulation of negative memories. • Eye movements are most effective with collateralized eye and dopamine dominance. • Optimizations for EMDR and SIRE are suggested. [ABSTRACT FROM AUTHOR]

Faces are processed best when they are presented in the left visual field (LVF), a phenomenon known as LVF superiority. Although one eye contributes more when perceiving faces, it is unclear how the dominant eye (DE), the eye we unconsciously use when performing amonocular task, affects face processing. Here, we examined the influence of the DE on the LVF superiority for faces using event-related potentials. Twenty left-eye-dominant (LDE group) and 23 right-eye-dominant (RDE group) participants performed the experiments. Face stimuli were randomly presented in the LVF or right visual field (RVF). The RDE group exhibited significantly larger N170 amplitudes compared with the LDE group. Faces presented in the LVF elicited N170 amplitudes that were significantly more negative in the RDE group than they were in the LDE group, whereas the amplitudes elicited by stimuli presented in the RVF were equivalent between the groups. The LVF superiority was maintained in the RDE group but not in the LDE group. Our results provide the first neural evidence of the DE's effects on the LVF superiority for faces. We propose that the RDE may be more biologically specialized for face processing. [ABSTRACT FROM AUTHOR]

Physiological palpebral fissure asymmetry is a common observation in a physician’s everyday practice. The goal of this study was to examine the relationship between palpebral fissure height (PFH) and ocular dominance. Sixty-nine healthy volunteers (42 female, 27 male) were included in this research, and ocular dominance was determined using hole-in-the-card and pointing-a-finger tests. Those volunteers with inconsistent test results were excluded. Standard photographs were taken of all of the subjects in the primary position with a consistent background and photographic equipment. The PFHs were measured using an ImageJ analyser, and a mixed ANOVA was used for the statistical analysis. Overall, 87% of the participants showed small differences in their PFHs, with their dominant eyes being significantly wider than their non-dominant eyes (10.51 ± 0.97 vs. 10.32 ± 1.03;p = .001). This study revealed that ocular dominance has a significant effect on the PFH. Further research is required to understand the importance of this association in daily practice. [ABSTRACT FROM PUBLISHER]

Unlike handedness, sighting eye dominance, defined as the eye unconsciously chosen when performing monocular tasks, is very rarely considered in studies investigating cerebral asymmetries. We previously showed that sighting eye dominance has an influence on visually triggered manual action with shorter reaction time (RT) when the stimulus appears in the contralateral visual hemifield with respect to the dominant eye (Chaumillon et al. 2014). We also suggested that eye dominance may be more or less pronounced depending on individuals and that this eye dominance strength could be evaluated through saccadic peak velocity analysis in binocular recordings (Vergilino-Perez et al. 2012). Based on these two previous studies, we further examine here whether the strength of the eye dominance can modulate the influence of this lateralization on manual reaction time. Results revealed that participants categorized as having a strong eye dominance, but not those categorized as having a weak eye dominance, exhibited the difference in RT between the two visual hemifields. This present study reinforces that the analysis of saccade peak velocity in binocular recordings provides an effective tool to better categorize the eye dominance. It also shows that the influence of eye dominance in visuo-motor tasks depends on its strength. Our study also highlights the importance of considering the strength of eye dominance in future studies dealing with brain lateralization. [ABSTRACT FROM AUTHOR]

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When individuals attempt to walk through the center of a doorway (i.e., spatial bisection), the body's midpoint at crossing can deviate from its true center. Such deviation could result from asymmetry in spatial cognition. However, previous studies failed to find a significant correlation between bisection performance during walking and that during line/spatial bisection. We investigated whether such failure would result from different effectors being used for bisection (i.e., body midpoint or finger/laser pointer). We also investigated whether the difference in an individual's eye dominance would affect the relationship. Thirty-two young adults (16 of them with right-eye dominance) participated. For a walking task, participants walked through the perceived center of a wide doorway. For a spatial bisection task, they observed the same doorway under two distance conditions (about 0.5 and 2 m) and aligned their body midpoint with the perceived center in the sagittal dimension. Both tasks were performed under three visual occlusion conditions (dominant eye, non-dominant eye, and no occlusion). The results showed that, for the spatial bisection task, occluding the dominant eye caused deviation of the bisected point to the contralateral side. However, for the walking task, such an effect was observed only in participants with a dominant right eye. Consequently, directional biases in both tasks were significantly correlated only for right-eye-dominant participants. These results suggest that, for right-eye-dominant individuals only, use of the same effector for both tasks showed a clear relationship between the two tasks. Possible explanations for these findings were discussed. [ABSTRACT FROM AUTHOR]