Effect of myopia management contact lens design on accommodative microfluctuations and eye movements during reading.

BACKGROUND: Soft contact lenses have been developed and licensed for reducing myopia progression. These lenses have different designs, such as extended depth of focus (EDOF) and dual focus (DF). In this prospective, double-masked, cross-over study, different lens designs were investigated to see whether these had impact on accommodative microfluctuations and eye movements during reading. METHODS: Participants were fitted with three lenses in a randomised order; a single vision (SV) design (Omafilcon A2; Proclear), a DF design (Omafilcon A2; MiSight), and an EDOF lens design (Etafilcon A; NaturalVue),. Accommodative microfluctuations were measured at 25 cm for at least 60s in each lens, using a Shin-Nippon SRW-5000 autorefractor adapted to continuously record accommodation at 22Hz. Eye movement data was collected with the Thomson Clinical Eye Tracker incorporating a Tobii Eye bar. Eye movements include fixations per row, fixations per minute, mean regressions per row, total number of regressions, and total rightward saccades. Accommodation data was analysed using power spectrum analysis. Differences between the lenses were compared using a related sample two-way Friedman test. RESULTS: Twenty-three participants (18-29 years) were recruited to take part. The average mean spherical error was -2.65D ± 1.42DS, with an average age of 23.4 ± 3.5 years. No significant difference for accommodative microfluctuations was found. Significant differences were found for fixations per row (P = 0.03), fixations per minute (P = 0.008), mean regressions per row (P = 0.002), and total number of regressions (P = 0.002), but not total rightward saccades (P = 0.10). Post-hoc analysis indicated the EDOF lens results were significantly different from the other lenses, with more regressive eye movements observed. CONCLUSIONS: Regressive saccades appear to increase when wearing EDOF lens designs, which may impact visual comfort. Further studies in children, over a longer period of adaptation are necessary to assess the potential impact of this finding on daily reading activities in children.

Hemodialyzed Individuals' Left Spatial Attentional Bias Is Normalized Following Successful Kidney Transplantation.

BACKGROUND: Healthy people have a leftward spatial attentional bias, called pseudoneglect. Individuals with end-stage renal disease (ESRD) who are receiving hemodialysis often demonstrate an increase in their leftward spatial attentional bias. Whereas a successful kidney transplant often improves the cognitive functions of individuals who previously received hemodialysis, the effect of a kidney transplant on this abnormal allocation of spatial attention has not been investigated. OBJECTIVE: To investigate the effects of kidney transplant on individuals who were being treated with dialysis and had an increase in their left spatial attentional bias. METHOD: The performance of 20 hemodialyzed individuals with ESRD on the line bisection test was compared to that of 17 demographically matched individuals with ESRD, who had received a kidney transplant, and 23 demographically matched healthy controls (HC). RESULTS: All of the participants exhibited a left spatial bias on the line bisection task. When compared with the HC, the hemodialyzed individuals demonstrated a significantly greater left spatial bias. There was, however, no difference in spatial bias between the HC and the individuals who had received a kidney transplant. CONCLUSION: A successful kidney transplant can improve patients' abnormal leftward allocation of spatial attention. However, future studies are needed to better understand the mechanisms of this spatial attentional bias in hemodialyzed individuals and the normalization of bias following transplantation.

The Allocation of Vertical Attention in Patients with End-Stage Renal Disease Receiving Dialysis.

Objectives: Alterations of spatial attention can have adverse effects, such a greater probability of accidents. Patients with end-stage renal disease (ESRD) receiving dialysis have stronger left-sided spatial attentional bias, suggesting that this disorder or treatment alters the brain networks that mediate spatial attention. The hemispheric networks that mediate the allocation of horizontal attention may also influence the allocation of vertical attention. However, the allocation of vertical spatial attention has not been studied in ESRD patients. Methods: Twenty-three ESRD patients receiving dialysis and 23 healthy right-handed controls performed line bisections using 24 vertical lines (24 cm long and 2 mm thick) aligned with the intersection of their midsagittal and coronal planes. Results: Hemodialyzed ESRD patients had a significantly greater upward bias than healthy controls. The magnitude of this bias was correlated with the duration of the kidney disease. Conclusions: The reason why upward attentional bias is increased in hemodialyzed ESRD patients is not known. Further research is needed to better understand the brain mechanism that might account for this bias, as well as its treatment. However, hemodialyzed ESRD patients and their families-caregivers should be made aware of this disorder to avoid accidents such as tripping.

Kidney transplantation and action-intentional improvements: Evidence from an ERP study.

Reaction slowing observed in dialyzed patients results from deficits in initiating and sustaining motor response mobilization. The present study aimed at investigating whether these deficits are reversible following successful kidney transplantation. To achieve this goal, behavioral and electrophysiological (EEG) data were assessed from healthy control participants as well as kidney transplant and dialyzed patients performing a series of reaction time tasks. The results demonstrated that in patients who received kidney transplant a normalization of response latencies and brain preparatory activity was observed. At the same time, when compared to healthy individuals, increased attention engagement was observed in both clinical groups of patients. No behavioral and electrophysiological indices of impaired monitoring were observed in any of the clinical groups.

Hemispheric stroke: Mood disorders.

Stroke causes many forms of disability, including emotional and mood disorders. Depression is the most common of these, affecting approximately one-third of stroke patients. Other disorders like mania, bipolar disorder, anxiety disorder, or apathy may also develop following stroke, although they are less common. The development of mood and emotional disorders is dependent on the severity of brain injury, the side of injury, and hemispheric location. Whereas a left hemispheric stroke often results in depression or a catastrophic reaction with anxiety, injury to the right hemisphere has predominantly been associated with the development of emotional indifference (anosodiaphoria) or euphoria. In this chapter, we discuss the mood disorders associated with hemispheric strokes and the neuropsychological mechanisms that might account for the clinical manifestations of these affective disorders.

Feeling and Looking Down: Impact of Depressive Symptoms on the Allocation of Vertical Attention.

BACKGROUND: Emotions and moods are often expressed using verbal, vertical spatial metaphors (eg, "I'm feeling down"). The reason for using these vertical metaphors is unknown; however, when individuals experience depressive symptoms, they often become self-reflective and ruminative. These mental activities are associated with activation of the default network, including the parietal lobes. The parietal lobes are a critical component of the dorsal visual attentional network, which allocates attention downward. Therefore, activation of the default network may create a downward bias of vertical attention. OBJECTIVE: To investigate whether depressive mood disposition, as measured by the number of depressive symptoms experienced by an individual, influences their allocation of vertical attention. METHODS: We used the Hospital Anxiety and Depression Scale to evaluate depressive symptoms in 48 right-handed individuals with a mean age of 57.31 (±17.14) years. We also asked the participants to mark the center (bisect) of 24 vertical and 24 horizontal lines. RESULTS: Overall, the individuals deviated their bisections of vertical lines upward (M=2.66 mm; SD=3.85). A stepwise linear regression analysis revealed that the number of depressive symptoms an individual experienced was significantly associated with a reduction in the magnitude of this upward vertical bias (P=0.009; R=0.138), such that the number of depressive symptoms was associated with the reduction (lowering) of their upward bias. CONCLUSION: Depressive symptoms may be associated with a relative lowering of the vertical attentional bias, and this lowering may be related to increased activation of portions of the default network.

Upper Vertical Spatial Neglect With A Right Temporal Lobe Stroke.

Individuals with a hemispheric infarction often reveal inattention to, or neglect of, contralesional lateral space (ie, hemispatial neglect). Individuals with a bilateral ventral temporal-occipital lesion have been shown to demonstrate upper vertical neglect, and those with a bilateral parietal-occipital lesion have been shown to demonstrate lower vertical neglect. However, to our knowledge, there have been no reports of individuals with vertical neglect from a unilateral hemispheric lesion. We report on a 72-year-old, right-handed male who developed transient left hemiparesis. On examination, he had left facial weakness and he bisected horizontal lines to the left of the midline (ie, ipsilesional neglect). In addition, on a line bisection test involving nine vertical line bisections, he demonstrated downward deviation in the majority of the trials; healthy individuals deviate upward. On brain imaging, our patient revealed a cerebral infarction, primarily affecting the right temporal lobe; the temporal lobes contain the ventral attentional network that allocates attention upward. There is also some evidence that, whereas the right hemisphere mediates attention upward, the left mediates attention downward. Therefore, injury to the right temporal lobe may account for our patient's upward neglect with downward deviation. However, further studies are needed to better understand the pathophysiology of vertical neglect.

Age-related changes in the allocation of spatially directed focal attention.

OBJECTIVES: Leftward deviation on a horizontal line bisection test (pseudoneglect) might be induced by right hemispheric dominance for mediating spatial or global attention, or a hemispheric asymmetry in the ability to spatially disengage attention. With aging, this leftward bias is reduced, likely due to the aging-related deterioration of right hemisphere mediated functions (right hemi-aging) or hemispheric asymmetry reduction in old adults (HAROLD). METHODS: Forty-seven healthy adults divided into younger and older groups performed a modified Posner spatial-attentional task. RESULTS: Overall, younger individuals responded faster to left than right-sided imperative stimuli. In contrast, older participants did not reveal a right-left asymmetry to imperative stimuli. The younger group also revealed a strong inverse relationship between the reaction time to right valid cues and the leftward attentional bias while performing the line bisection task (pseudoneglect). CONCLUSIONS: Our results provide support for both the right hemisphere spatial-attentional dominance hypothesis of pseudoneglect and the right hemi-aging hypotheses.

Attentional system of very prematurely born preschoolers.

Recent studies indicate that premature children are at risk for difficulties with cognitive development and have increased incidence of ADHD as well as other behavioral disorders. Although the exact mechanism accounting for these children's neuropsychological abnormalities is unknown, there is evidence to suggest that the cognitive and behavioral disturbances seen in this population may result from a slower development of the attentional system. However, it remains unclear whether prematurity affects the development of the entire attention system or if prematurely born children have a selective insufficiency of components of this system (i.e., orienting, alerting, executive). We compared the efficiency of the attentional system of very prematurely born children and full-term controls at 5 years of age, using the Attention Network Task-Child Version. In comparison to full-term peers, very preterm children exhibited inefficient orienting of attention, whereas there was no group difference in the efficiency of alerting and executive aspects of attention. The reason for the selectively suboptimal orienting of attention in very prematurely born preschoolers remains unclear; it is possible that the neural substrates of this attentional subsystem are particularly underdeveloped in the preschool period in this cohort. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Improved Accuracy on Lateralized Spatial Judgments in Healthy Aging.

OBJECTIVES: Healthy young adults often demonstrate a leftward spatial bias called "pseudoneglect" which often diminishes with aging. One hypothesis for this phenomenon is an age-related deterioration in right hemisphere functions (right hemi-aging). If true, then a greater rightward bias should be evident on all spatial attention tasks regardless of content. Another hypothesis is a decrease in asymmetrical hemispheric activation with age (HAROLD). If true, older participants may show reduced bias in all spatial tasks, regardless of leftward or rightward biasing of specific spatial content. METHODS: Seventy right-handed healthy participants, 33 younger (21-40) and 37 older (60-78), were asked to bisect solid and character-letter lines as well as to perform left and right trisections of solid lines. RESULTS: Both groups deviated toward the left on solid line bisections and left trisections. Both groups deviated toward the right on right trisections and character line bisections. In all tasks, the older participants were more accurate than the younger participants. CONCLUSIONS: The finding that older participants were more accurate than younger participants across all bisection and trisection conditions suggests a decrease in the asymmetrical hemispheric activation of these specialized networks important in the allocation of contralateral spatial attention or spatial action intention.

Age-Related Changes in the Allocation of Vertical Attention.

OBJECTIVES: Healthy individuals often have a leftward and upward attentional spatial bias; however, there is a reduction of this leftward bias with aging. The right hemisphere mediates leftward spatial attention and age-related reduction of right hemispheric activity may account for this reduced leftward bias. The right hemisphere also appears to be responsible for upward bias, and this upward bias might reduce with aging. Alternatively, whereas the dorsal visual stream allocates attention downward, the ventral stream allocates attention upward. Since with aging there is a greater atrophy of the dorsal than ventral stream, older participants may reveal a greater upward bias. The main purpose of this study was to learn if aging influences the vertical allocation of spatial attention. METHODS: Twenty-six young (17 males; mean age 44.62±2.57 years) and 25 healthy elderly (13 males; mean age 72.04±.98 years), right-handed adults performed line bisections using 24 vertical lines (24 cm long and 2 mm thick) aligned with their midsagittal plane. RESULTS: Older adults had a significantly greater upward bias than did younger adults. CONCLUSIONS: Normal upward attentional bias increases with aging, possibly due to an age-related reduction of the dorsal attentional stream that is responsible for the allocation of downward attention. (JINS, 2018, 24, 1121-1124).

The influence of rightward and leftward spatial deviations of spatial attention on emotional picture recognition.

OBJECTIVES: Several studies have reported that positive emotions are primarily mediated by the left hemisphere and negative emotions by the right hemisphere. Since each hemisphere primarily allocates attention toward the contralateral hemispace, we wanted to learn how inducing a spatial attentional orienting bias to right and left egocentric hemispace might influence the recognition and perception of visually presented emotional scenes. METHOD: Participants were 42 healthy, right-handed young adults. To induce a directional change in spatial attention, we used a horizontal prism adaptation (PA) method that trains participants to allocate attention in the opposite direction to the prism-induced deviation. After each PA, participants evaluated a set of affective (positive/neutral/negative) pictures from the Nencki Affective Picture System. Responses in each emotional category and reaction times were recorded and analyzed. RESULTS: There was no PA effects on reaction times between the experimental conditions. However, when compared to the control condition, both rightward and leftward PA resulted in a reduction of correctly recognized positive emotions as well as altering the perception of neutral and positive pictures as more emotionally negative. CONCLUSIONS: The results do not support the proposed left-right spatial attentional valence hypothesis. The reason why PA in both directions negatively altered emotion perception is not known. However, a portion of the dorsal visual stream, the parietal lobes, and especially the right parietal lobe, are critical for mediating horizontal egocentric spatial attention. The right hemisphere also mediates negative emotions, and the activation of this right hemispheric attention network may have induced the changes in perception found in this study. However, future studies are needed to further test this hypothesis.

Leftward Bias of Visual Attention in Patients with End-Stage Renal Disease Receiving Dialysis: A Neglected Phenomenon.

BACKGROUND AND OBJECTIVE: Patients with end-stage renal disease (ESRD) who are receiving dialysis often have cognitive and behavioral changes, including impairments in sustained attention. Impairments in sustained attention appear to be the consequence of right hemisphere dysfunction. Right hemisphere brain networks are also important for the allocation of spatial attention. Therefore, the objective of this study was to learn whether patients with ESRD receiving dialysis might also have a spatial attentional bias. PARTICIPANTS AND METHODS: Eighteen nondemented patients with ESRD receiving dialysis but without any neurologic diseases (age range: 20 to 60 years) and 18 demographically matched healthy controls participated in this study. Participants performed a standard line bisection task using 24 horizontal lines (24 cm long and 2 mm thick) that were sequentially placed at eye level on a white board. RESULTS: Patients receiving dialysis had a significantly greater leftward bias than healthy controls. CONCLUSIONS: Patients with ESRD receiving dialysis appear to have an impaired ability to correctly allocate their spatial attention (spatial neglect). Although the reason for the patients' leftward bias needs to be elucidated, ESRD and/or dialysis may have induced right frontal-subcortical dysfunction that disinhibited the right parietal lobe, producing a left-sided attentional bias. Further studies are needed to test this hypothesis.

The time course of blur adaptation in emmetropes and myopes.

PURPOSE/BACKGROUND: This study examined the effect of myopic defocus on visual acuity (VA) over time, with attention being paid to the first point at which blur adaptation had a significant and measurable effect on defocused VA. Visual acuity was sampled at a higher rate than previous studies in order to assess the time course of blur adaptation processes in myopic and emmetropic observers. METHODS: Participants were 24 normally-sighted observers (12 emmetropes and 12 myopes, median age: 22.5 years). All ametropic participants wore their full refractive correction throughout the experiment. 1 D and 3 D of myopic defocus were introduced in two separate, randomised sessions. Visual acuity was measured using Test Chart 2000 at 2 min intervals over a 30 min session whilst looking through defocus lenses. Recovery clear VA was also measured every 2 min for a further 20 min. RESULTS: Defocused VA was found to improve significantly within 4 min after the introduction of defocus for both 1 D (P < 0.0001) and 3 D conditions (P < 0.0001). The improvements reached a plateau shortly after, with no significant further improvements in defocused VA after 6 min. There were no significant differences found in the temporal blur adaptation profiles between emmetropes and myopes (P = 0.267). Data were fitted with an exponential decay function; the lowest R(2) value for this fit was 0.95. CONCLUSIONS: Blur adaptation has a clinically significant and measurable effect on VA within 4 min of exposure to defocus. This finding indicates that the visual system instigates the neural compensatory mechanisms shortly after the appearance of defocus. Our results relate particularly to real-life vision of uncorrected myopes or myopes who remove their correction for part of the day.

Effect of blur adaptation on human parafoveal vision.

PURPOSE: This study was conducted to investigate whether neural compensation for induced defocus can alter visual resolution in other areas of the human retina beyond the fovea. In certain circumstances, the blur adaptation response may be influenced by refractive status. METHODS: The effect of blur adaptation on the central 10° of the retina was investigated in 20 normally sighted observers (10 emmetropes and 10 myopes; median age, 21 years). Visual acuity (VA) was measured at the fovea and at five locations of the parafoveal nasal visual field (2°, 4°, 6°, 8°, and 10°) with best corrected distance vision. Myopic defocus of 1 D was introduced, and the same measurements were repeated immediately before and after a 30-minute adaptation. RESULTS: VA declined with increasing eccentricity in the clear, blurred, and blur-adapted viewing conditions. The rate of decline was quantified by the parameter E2, which represents the amount of eccentricity dependence of the acuity task. Foveal and parafoveal VA decreased with the introduction of optical defocus and improved significantly after a period of blur adaptation. The consistent value of E2 in each condition indicated that these changes in VA were not eccentricity dependent. Changes in VA under blurred and blur-adapted conditions were of similar magnitudes in myopic and emmetropic observers. CONCLUSIONS: Neural adaptation to blur improves VA under defocused conditions in the parafovea as well as the fovea, indicating that the underlying compensatory mechanism acts across a range of spatial scales and independently of retinal eccentricity. Foveal and parafoveal blur adaptation does not vary with refractive error.

Simultaneous measurement of objective refraction, accommodation response and axial length of the human eye.

PURPOSE: Accurate measurements of ocular biometry and objective refraction are of vital importance to research laboratories working in the area of refractive error development and oculomotor function. A number of commercially available instruments can provide these measurements, and are used in both their intended modes, and with modifications to increase their research utility. A limitation that exists currently is the inability to conduct simultaneous measurements of refractive error or accommodation response, and the axial length of the same eye. In this technical note we provide details of a method to adapt the Zeiss IOLMaster and the Shin-Nippon SRW-5000 infrared optometer to simultaneously measure refraction and axial length. METHODS: The optical modification used to combine the measurement paths of the IOLMaster and SRW-5000 instruments consists of a narrow band-pass filter, and optical relay to extend the working distance of the IOLMaster, and an electronic system to provide synchronisation between the IOLMaster and the SRW-5000 continuous accommodation recording system. The optical modification was tested on model eyes, and on a cohort of 20 human eyes. The combined system was then used to measure accommodation response and axial length simultaneously in a single participant. RESULTS: Inclusion of the optical modification in the IOLMaster pathway induced a 0.004 mm shift in the average measurement of a calibration eye, and an average difference of 0.001 mm for a cohort of human eyes. For the SRW-5000, inclusion of the modified optics induced a +0.15 D shift in the spherical component of refraction measurements made on a model eye, and an average shift of +0.12 D in the spherical component of measurements made on a cohort of human eyes. Simultaneous measurement of accommodation response and axial length in a single participant revealed that a change in stimulus vergence from 0 to 5 D caused an average accommodation response of 3.89 D, and an average transient axial length change of 0.059 mm. CONCLUSIONS: The system described provides a useful method of achieving simultaneous measurements of axial length, objective refraction and accommodation response in a human eye.