The effect of lutein supplementation on visual fatigue: A psychophysiological analysis

We used psychophysiological technology to examine the effect of an oral supplement, a combination of lutein, zeaxanthin and blackcurrant extract (LUT), on visual fatigue, within the context of a randomized, double-blind, placebo-controlled cross-over trial. The LUT supplement and placebo samples were randomly assigned to thirteen participants, who took the samples for two LUT (and vice versa) for another 2 week. Each participant completed visual proof reading tasks for 2 h during each of four testing sessions. Saccade tests were administered before and after the proof reading task, during which the participants moved their eyes back and forth between two targets positioned in the center of two checkerboards. We recorded EEG, EOG, heart rate, and facial muscle potential/performance during the saccade tests. Blood pressure was measured and subjective fatigue and stress scores were collected before and after the proof reading task. We averaged EEG starting at saccade offset in order to analyze eye fixation related potentials (EFRP). Our results suggested that the proof reading task induced visual fatigue. An analysis of EFRP and other psychophysiological data revealed significant differences between the LUT and placebo conditions. These results suggest that supplementation with LUT could help to reduce symptoms of visual fatigue.     

Measuring visual fatigue and visual discomfort associated with 3‐D displays

Abstract— This research identifies methods for signs of visual complaints associated with stereoscopic displays. Two potential causes for contradictory results concerning these signs in previous research are hypothesized: (1) not all clinical tests are equally appropriate and (2) there is a natural variation in susceptibility amongst people with normal vision. An optometric screening differentiated participants with moderate binocular status (MBS) from those with good binocular status (GBS). In a 2 × 2 within‐subjects design (2‐D vs. 3‐D and MBS vs. GBS), a questionnaire and eight optometric tests (i.e., binocular acuity, aligning prism, fixation disparity, heterophoria, convergent and divergent fusional reserves, vergence facility, and accommodation response) were each administered before and immediately after a reading task. Results revealed that only participants with MBS in 3‐D conditions showed clinically meaningful changes in fusion range, experienced more visual discomfort, and performed worse on the reading task. Acombination of fusion range measurements and self‐report is appropriate for evaluating visual complaints of stereoscopic stills, and people with a MBS are more susceptible to visual complaints associated with stereoscopic displays. A simple measurement tool, i.e., the ratio of reading performance between 2‐D and 3‐D, to categorize people based on their binocular status is proposed.     

Comparison of changes in visual fatigue and ocular surface after 3D and 2D viewing with augmented reality glasses

The extensive use of electronic devices commonly results in visual discomfort, particularly in stereoscopic display. Augmented Reality (AR) is a mixed technology that superimposes three-dimensional (3D) digital data onto an image of reality. Even though the visual health evaluation of 3D contents has been widely concerned, the difference between 3D and two-dimensional (2D) viewing using AR display was rarely studied. We aimed to compare the changes in visual fatigue and ocular surface parameters after 3D and 2D viewing with optical waveguide AR glasses for one hour (1hr). In the experiment, thirty young healthy participants watched the same film in 2D and 3D mode separately using AR glasses with one week interval. Subjective visual fatigue questionnaire and ocular examinations were evaluated at 3 time points: pre-watching, post-2D and post-3D visual task for 1hr. Lipid layer thickness (LLT) and total blink (TB) were evaluated with the LipiView interferometer. Tear meniscus height (TMH) and noninvasive tear breakup time (NIBUT) were measured using Keratograph 5M. The effect of viewing 2D and 3D videos for 1hr with AR glasses suggested slight visual discomfort except the symptom of pain and dullness. The lipid layer thickness and total blink showed increasing trends in both post-visual task but more obvious after 2D viewing. Blinking patterns and tear film stability are meaningful for video display terminal users in visual health education. Ocular parameters are needed to be considered in the design and usage of future AR applications.     

The correlation between visual fatigue and duration of viewing as assessed by brain monitoring

Duration of viewing was considered as one of the most important factors of 3D visual fatigue. However, their relationship was not well studied. We proposed to use brain monitoring techniques to reveal more details about the variety of brain activity while watching three‐dimensional (3D) content. We investigated the spectral patterns in the electroencephalogram related to various duration of viewing and showed the power spectral density varied significantly along with the development of fatigue over occipital lobe, parietal lobe, and right frontal lobe. Moreover, we first described the trend of brain activity during 3D content viewing and revealed the location of significant components related to 3D visual fatigue. We believe that the absolute power describes more information and may be a better indicator of 3D visual fatigue assessment compared with relative power. We also first revealed the cortex location that is related to 3D visual fatigue. Our findings may help to define appropriate electroencephalogram features for online 3D visual fatigue detection while participants viewing 3D content.     

Investigation of legibility and visual fatigue for simulated flexible electronic paper under various surface treatments and ambient illumination conditions

This study employs simulated electronic paper to investigate critical issues and focuses on improving legibility of display and reducing users' visual fatigue. Three critical factors - choice of surface treatment, ambient illumination, and bending curvature - are evaluated through the method of a letter-search task. The results show that subjects performed better on legibility and felt less visual fatigue with an anti-glare treatment. Choosing the better anti-glare treatment instead of the anti-reflection series can save significant cost for manufacturers. In addition, ambient lighting of 1500 lux is more appropriate for reading on electronic paper than an environment with extreme illumination (e.g., 8000 lux). The present study also found that curvature had no impact on legibility or visual fatigue. These evaluations of simulated electronic paper may provide manufacturers useful information in fulfilling ergonomic requirements for product design.     

Spectral influence of the normal LCD,blue-shifted LCD,and OLED smartphone displays on visual fatigue: A comparative study

In this study, we investigated the influence of the light spectra of the normal LCD, blue-shifted LCD, and OLED smartphone displays on visual fatigue based on subjective and objective measurements. The illuminance of the retinal photoreceptors was calculated for the three displays to quantify the components of the light spectra. The results showed that the accumulated visual fatigue decreased for the display with lower retinal illuminances of the S-, M-, and L-cones, and ipRGCs when the luminance and CCT were the same. In addition, the display with larger retinal illuminances of the M- and L-cones induced more visual fatigue related to dry eye. Hence, a slight shift of the blue light peak toward a longer wavelength is recommended for reducing visual fatigue. Furthermore, an evaluation model of the overall visual fatigue level is proposed.     

Investigation and modeling of visual fatigue caused by S3D content using eye-tracking

3D has been one of the most important technologies of the last decade having an exponential progression. Nevertheless, several problems such as visual discomfort and visual fatigue have slowed its progression for homes. This factor decreases significantly the overall quality of experience from watching 3D content and reduces the level of satisfaction of a user. This study explores the accumulation of visual fatigue when watching 3D video in close to real-life conditions. In order to obtain more information about visual discomfort, an hour of eye-tracking experiments have been conducted. Investigations have been made by analyzing information provided both by users through questionnaires and visual gaze characteristics recording. Obtained results are compared to data produced when watching 2D. The deep statistical analysis showed that time and video content have an influence on video fatigue accumulation and visual functions. With respect to the obtained results, a model has been proposed based on video characteristics (motion activity, disparity range and changes) and the previous state of visual fatigue.     

Assessment of visual fatigue caused by stereoscopic disparity based on multimodal measurement

Given the prevalence of visual fatigue induced by stereoscopic display, research on the neural mechanism of visual fatigue was limited. The goal of this study was to investigate the effect of stereoscopic display with different horizontal disparities on visual fatigue based on subjective questionnaire, ophthalmological parameters, eye movement and electrocardiogram (ECG). Subjects felt more headache, uncomfortable and dry eyes after watching 70-minute enhanced 3D display with larger negative disparity than normal 3D display. Meanwhile, visual function tear film break-up time (TBUT) reduced, microsaccade mean pupil diameter (MMPD) increased and heart rate variability (HRV) changed more significantly after watching enhanced 3D display. Overall, these results demonstrated that enhanced 3D display had a better sense of immersion, but it induced more visual fatigue significantly than normal 3D display.     

Proactive mental fatigue detection of traffic control operators using bagged trees and gaze-bin analysis

Most of existing eye movement-based fatigue detectors utilize statistical analysis of fixations, saccades, and blinks as inputs. Nevertheless, these parameters require long recording time and heavily depend on eye trackers. In an effort to facilitate proactive detection of mental fatigue, we introduced a complemental fatigue indicator, named gaze-bin analysis, which simply presents the eye-tracking data with histograms. A method which engaged the gaze-bin analysis as inputs of semisupervised bagged trees was developed. A case study in a vessel traffic service center demonstrated that this approach can alleviate the burden of manual labeling as well as improve the performance of fatigue detection model. In addition, the results show that the approach can achieve an excellent accuracy of 89%, which outperformed other methods. In general, this study provided a complemental indicator for detecting mental fatigue as well as enabled the application of a low sampling rate eye tracker in the traffic control center.     

Effect of viewing a three-dimensional movie with vertical parallax

The vertical parallax of both eyes, caused by tilting the head when watching three-dimensional (3D) television or movies, can induce visual fatigue or visually-induced motion sickness. The purpose of the present study was to investigate levels of discomfort and fatigue and eye movements induced by viewing a 3D movie with vertical parallax. Two experiments were conducted to investigate the relationship between the degree of vertical parallax and the magnitude of the effect. The results indicate that the viewer’s feeling of visual malaise increases as the angle of the screen increases, with respect to the observer’s head, because eye movement does not compensate for the parallax in the vertical direction. Binocular rivalry is believed to occur when viewing a 3D movie with vertical parallax, which may induce even more visual malaise.     

A quantitative measurement of LCD and PDP TVs for human visual preference and fatigue

This study was conducted by subjective and objective measurement, to clarify the complex relationships among human visual preference and fatigue of major Flat Panel Display TVs with related physical and physiological factors. In the subjective measurement, comparison tests with 24 subjects were conducted and the semantic differential method with factor analysis was carried out for six TVs with different room luminance and length of watching time. The comparison test yielded identification of the most preferable display, which showed little connection with the TV luminance for any length of watching time and room luminance. From the statistical factor analysis of semantic differential method, significant factors were extracted for describing human visual preference. In the objective measurement, the eye motion tracking camera was used to detect the eye response and thus generated physiological data corroborated the significant factors extracted from the subjective measurement. This study allows the human perceptual preference and fatigue of electronic displays to be quantitatively measured with psychological and physiological factors and will tell which parameters are significant and guide the manufacturer in making the optimum TVs.     

Using electromyography responses to investigate the effects of the display type,viewing distance,and viewing time on visual fatigue

The rapid success of 3D display technology and daily accessibility to 3D images has greatly increased the interest in such applications for a wide range of fields. This paper compares the effects of watching movies with 2D and 3D displays depending on the viewing distance (3H vs. 6H, where H is the height of the screen) and viewing time to determine the visual fatigue using electromyography (EMG) in terms of the percentage of maximum voluntary contraction (%MVC) of the orbicularis oculi (OO) muscle activity and a subjective visual discomfort score. Twenty healthy male university students with a mean age of 27.7 ± 2.53 years participated in this study as volunteers. None had color blindness, and all had normal vision acuity. A mixed-measures design was performed. The results showed that the viewing time and distance had significant effects on the %MVC and OO muscle activity depending on the display type. Watching the 3D display from a short viewing distance produced significantly high visual fatigue compared to watching the 2D display from a short viewing distance. However, the 3D display seemed to be less stressful than the 2D display at long viewing distances.     

Comparison of visual fatigue caused by head-mounted display for virtual reality and two-dimensional display using objective and subjective evaluation

This study aimed to evaluate objective and subjective visual fatigue experienced before and after performing a visual task while using a head-mounted display for virtual reality (VR-HMD) and two-dimensional (2D) display. Binocular fusion maintenance (BFM) was measured using a binocular open-view Shack–Hartmann wavefront aberrometer equipped with liquid crystal shutters. Twelve healthy subjects performed the BFM test and completed a questionnaire regarding subjective symptoms before and after performing a visual task that induces low visually induced motion sickness (VIMS). BFM (p = .87) and total subjective eye symptom scores (p = .38) were not significantly different between both groups, although these values were significantly lower after the visual task than before the task within both groups (p < .05). These findings suggest that visual fatigue after using a VR-HMD is not significantly different from that after using a 2D display in the presence of low-VIMS VR content.

Practitioner summary: Objective and subjective evaluation of visual fatigue were not significantly different with the use of a head-mounted display for virtual reality (VR-HMD) and two-dimensional display. These results should be valuable not only to engineers developing VR content but also to researchers involved in the evaluation of visual fatigue using VR-HMD.

Abbreviations: VR: virtual reality; VR-HMD: head-mounted display for virtual reality; BFM: binocular fusion maintenance; BWFA: binocular open-view Shack–Hartmann wavefront aberrometer     

Work domain analysis for enhancing collaborations: a study of the management of microsystems design

Collaboration is an important process that enables organisations to achieve goals or solve problems and, in design processes, is an important factor for accomplishing interdisciplinary and multidisciplinary tasks. An understanding of the functional configuration of organisations could therefore offer a useful insight into collaborations of designers. This study makes use of work domain analysis (WDA) to analyse the management of design by organisations within the microsystems technology (MST) domain. The WDA considers the functional configuration of MST companies in terms of management constraints and boundaries. This study also makes use of the WDA to suggest ways of establishing collaborative design and enhancing collaboration between organisations. Practitioner Summary: The results of this methodical analysis offer useful insights for managing design functions. This study also presents recommendations for enhancing collaboration in organisations. The ability to manage and collaborate in design functions is valuable for improving the productivity, cost-effectiveness and time-to-market systems.     

Influence of ambient-tablet PC luminance ratio on legibility and visual fatigue during long-term reading in low lighting environment

We examine the effect of the (luminance) ratio of ambient luminance to tablet surface luminance on text legibility and fatigue over 1 h of long-term reading with a tablet PC in low-ambient-luminance environments limited to 45 cd/m² (illuminance ~230 lx). Four reading-pattern subject experiments are carried out at ambient-luminance-to-tablet-surface-luminance ratios of 1:1, 1:3, 1:6, and 1:9 at 15 and 45 cd/m². As per legibility tests based on the semantic differential (SD) method, we find that subjects experience glare at luminance ratios of 1:6 and 1:9, and it is difficult to read text at the luminance ratio of 1:9 under ambient luminances of 15 and 45 cd/m². Based on subject fatigue (determined by subjective symptom survey), we find that the feeling of fatigue, according to the change in the luminance ratio, most affects the Fuzziness group among the five subjective fatigue groups. Based on physical fatigue determined using the critical flicker fusion frequency (CFF) value, we observe significant CFF differences before and after reading for luminance ratios of 1:1 and 1:9 at the ambient luminance of 45 cd/m² and for the ratio of 1:9 when the ambient luminance is 15 cd/m². A larger difference between the ambient and surface luminances corresponds to higher CFF variation rates and more fatigue.     

Visual evoked potentials as indicators of the workload at visual display terminals

No physiological correlates are known for visual fatigue produced by prolonged viewing of visual display terminals (VDTs). The primary aim of the present study was to find a physiological correlate of a performance measure which is related to fatigue. The assumption was that a change in the state of fatigue expresses itself in fluctuations of accommodation. If indeed variations in accommodation are indicative of fatigue, then visual evoked potentials (VEPs) might be used for the objective estimation of fatigue, because pattern EPs are highly sensitive to the quality of the retinal image.

In a realistic visual task, the VEP to pattern onset and the performance to a binary task are recorded simultaneously. Both indicators of fatigue, the amplitude of the VEP and the reaction time, proved to be sensitive to the workload of the task. If accommodation effort was increased, then reaction time increased and VEP amplitude decreased. Thus, VEPs are an indicator of the workload of a visual task. This allows comparison of the fatiguing effects of various office settings on the basis of the pattern EP of a particular subject. However, because VEP amplitude and reaction time do not have the same relation amongst subjects, the pattern EP cannot be used for inter-individual comparison.     

The effect of VDU colour on visual fatigue in the fovea and periphery of the visual field

The effect of the display of a visual display unit (VDU) on visual fatigue was investigated using the critical flicker frequency (CFF) paradigm. The results indicate that fatigue, as measured by CFF, varied as the VDU colour and eccentricity changed in the visual field. It was found that blue and red, that is, both extremes of the visible spectrum, strongly caused visual fatigue in the visual field when compared to green and yellow, that is, the middle range of the visible spectrum. Furthermore, for yellow and blue, VDU signal fatigue tended to decrease as the distance from the fovea increased. whereas for red and green, it increased by up to 10° in the periphery and then tended to decrease. The results indicate that yellow and green cause less fatigue in the periphery and fovea, respectively.     

Research on the effect of contrast enhancement and illumination condition on 3D visual fatigue

3D visual comfort can be influenced by such common factors as binocular parallax, 3D image contrast, viewing distance, and illumination condition. This paper investigates the effect of contrast enhancement and illumination condition on 3D visual fatigue by performing a visual fatigue measurement experiment, of which subjects need to watch 3D images under two illumination conditions and finish a comfort judgment task. The proportion of discomfort images, the subjective evaluation of visual fatigue under 100 lux and 500 lux illumination conditions, the effect of image contrast enhancement on 3D visual fatigue, and the relationship between visual fatigue and proportion of discomfort images were analyzed, respectively. The experimental results showed that both the contrast enhanced by Laplacian algorithm and low illumination condition have positive influence on 3D visual perception of eyes; the 3D visual fatigue of contrast enhanced by Laplacian algorithm under low illumination condition was less than other situations in the experiment. Moreover, it was examined that the proportion of discomfort images can be potential prediction indicator of the 3D visual fatigue.     

Measuring the effects of visual demand on lateral deviation: a comparison among driver's performance indicators

In this study we compare the efficacy of three driver's performance indicators based on lateral deviation in detecting significant on-road performance degradations while interacting with a secondary task: the High Frequency Component of steering wheel (HFC), and two indicators described in ISO/DIS 26022 (2007): the Normative and the Adapted Lane Change Test (LCT). Sixteen participants were asked to perform a simulated lane-change task while interacting, when required, with a visual search task with two levels of difficulty. According to predictions, results showed that the Adapted LCT indicator, taking into consideration individual practices in performing the LCT, succeeded in discriminating between single and dual task conditions. Furthermore, this indicator was also able to detect whether the driver was interacting with an easy or a difficult secondary task. Despite predictions, results did not confirm Normative LCT and HFC to be reliable indicators of performance degradation within the simulated LCT.     

Assessing the visual quality of sanitary ware by fuzzy logic

Quality control systems focus on maintaining standards in manufactured products. To improve the homogeneity of batches received by final users and to detect manufacturing defaults, a visual control stage is integrated into production line before the packing operation. At this stage, the products are inspected, mostly by human eye, for their obvious external defects; e.g., chips, cracks, scratches, holes and pitting, lumps, spots, notches, and glazing. This task is often referred to as visual inspection which is important to categorize the final products into quality-constant batches. Prototypes are of invaluable help while inspecting the visual attributes of products. Visual quality of products is assessed with respect to these standard units and some quality ratings are made there on the results. However, assessing visual quality is somewhat an ambiguous and troublesome work. Therefore, it will be helpful to utilize a decision making technique, such as fuzzy logic, to facilitate and improve the process. This paper addresses first to the significance of visual inspection and assessment of visual quality of industrial products, and second, gives a unique application of visual quality assessment of vitreous china ceramic sanitary wares by using fuzzy logic method.