Factors affecting accommodative response while viewing a video display terminal

The purpose of this study was to determine if accommodative responses to positive and negative contrast video displays differ significantly under two different levels of ambient illumination. The accommodative responses of 20 optometry students were measured (using a vernier Badal optometer) while characters on a video display terminal (VDT) were viewed binocularly under different screen and surround illumination conditions. Results showed no significant difference in accommodative response between negative and positive contrast VDT screens, but did reveal statistically significant differences (p\u3c.05) for two levels of ambient illumination. For both negative and positive contrast conditions, the lower ambient level was associated with a decreased accommodative response (greater lag of accommodation)

Visual fatigue and the driver

The last fifty years of research on visual fatigue are surveyed, with special emphasis on results that may be important in the context of driving. Over that time, ideas about visual fatigue have varied, ranging from a broad application of the label eyestrain, to virtually any visual complaint (including poor acuity), to more specific applications of the term to mean visual discomfort associated with lengthy near-vision tasks. Much of the research reviewed concerns visual fatigue in the workplace, and places particular emphasis on extended use of video displays. One consequence of this emphasis on specific workplace circumstances is that substantial portions of the work on visual fatigue may not be fully applicable to driving. The mechanisms developed to explain workplace visual fatigue may not be strongly engaged in driving. This is especially likely for research that links visual fatigue to oculomotor changes in vergence and accommodation after near work. Visual fatigue in driving is likely to be more strongly related to mechanisms such as ocular surface irritation that may occur as a consequence of eyeblink suppression, or to declines in arousal level that may occur over the course of a lengthy drive. Research directions on possible links between visual fatigue and vehicle lighting are discussed, along with options for measurement.University of Michigan Industry Affiliation Program for Human Factors in Transportation Safetyhttp://deepblue.lib.umich.edu/bitstream/2027.42/61186/1/100999.pd

Human Factors Considerations in System Design

Human factors considerations in systems design was examined. Human factors in automated command and control, in the efficiency of the human computer interface and system effectiveness are outlined. The following topics are discussed: human factors aspects of control room design; design of interactive systems; human computer dialogue, interaction tasks and techniques; guidelines on ergonomic aspects of control rooms and highly automated environments; system engineering for control by humans; conceptual models of information processing; information display and interaction in real time environments

Human Factors Compatibility Concerns in the Selection of Display Technologies for Computer and Data Terminals

Human factors considerations are often overlooked in the selection of electronic computer displays. When cost is used as the only determining factor, the resulting product may not be commercially successful because of an inadequate display. To help avoid this situation, designers and users should be aware of the various factors involved in proper display selection. These factors were developed by a synthesis of existing scientific and industrial literature on the subject and are explained in this paper. The first factor is a basic knowledge of the structure, characteristics, and function of the human visual system. The theory of sight, anatomy of the eye, visual perception, and photometric and nonphotometric parameters are covered. The human factors elements of visual response comprise the second factor. The adverse effects of display use as well as ergonomic standards, fonts, color, modes, and the use of status indicators are discussed. The last factor concerns displays. The various available and projected technologies along with comparisons, and applications are presented. Display evaluation criteria are listed to provide guidelines for proper selection

Effect of different alarm interfaces on controller response

Pipelines transport millions of barrels of petroleum products every day. Oil and gas pipelines have become important assets of the economic development of almost any country. Government regulations or internal policies regulate the safety of the assets for the population and environment where these pipelines run. Various strategies and technologies have been introduced for monitoring pipelines, but the most common technology to protect pipelines from occasional hazardous incidents is Computational Pipeline Monitoring (CPM). This technique collects and gathers information from the field related to pressures, flows, and temperatures to estimate the hydraulic behavior of the product being transported. Using the gathered information CPM systems compare its values with standard values and provides a notification if any anomaly or unexpected situation occurs. The result is an alarm to an operator in a supervisory control room. According to Hollifield, it is becoming an increasing problem that there is no standard for plant operators yet, whereas improved design can lead to better performance (Hollifield et. al., 2007). So, the objective of this experiment was to explore the effect of different alarm interfaces on controller response at different alarm rates. A simulated liquid pipeline system was developed and a between subject experimental design was performed to evaluate three different types of alarm window interfaces (Categorical, Chronological, and Revised Categorical), two alarm rates (10 in 10 minutes and 20 in 10 minutes), and three levels of alarms (high, medium, and low). Thirty one participants participated in this research, and the performance of participants was measured in terms of acknowledgement time, response time and the accuracy of response. Results showed that the participants’ performance in terms of response time, acknowledgement time, and accuracy of response was significantly different between chronological, categorical, and revised categorical displays. Data analysis showed that the means were shorter in revised categorical display in terms of response time, acknowledgement time, and accuracy of response. This study will be useful in developing new standards for alarm display

Electronic Image Detectability under Varying Illumination Conditions

Light in the built environment plays an essential role in the vision and the health of humans through non-visual receptors in the eyes. Unfortunately, image analysts and other Air Force personnel who engage in the detection of objects on softcopy displays are often required to work in very dimly-lit or dark environments as higher illumination reduces the contrast of displayed information. Literature has shown that increases in light exposure improves circadian rhythm entrainment and reduces the negative health consequences of insufficient lighting. This research examines the effects of indoor lighting to determine if increases in ambient illumination or changes to the orientation of light fixtures improves or degrades alertness and visual performance. Positive findings of this study would lead to changes in the environment of image analysts, increasing productivity and long-term health. In a controlled environment, twelve participants were exposed to D65 ambient light at levels of 0, 21, 32, and 43 lux, through overhead lighting, wall-washing, and under-desk illumination orientations. During exposures, participants were asked to visually identify variations in low-contrast Gabor patches on a display. The data was used to calculate the contrast threshold of detectability and response times of participants, thus indicating visual performance. Surveys also measured the subjective alertness and discomfort of participants. Results showed that the orientation of light fixtures significantly affects participant sleepiness, weariness, and discomfort. Additionally, the results indicate that visual detection performance is improved with higher ambient illumination levels employed within this research

TFOS lifestyle: Impact of the digital environment on the ocular surface

Eye strain when performing tasks reliant on a digital environment can cause discomfort, affecting productivity and quality of life. Digital eye strain (the preferred terminology) was defined as “the development or exacerbation of recurrent ocular symptoms and/or signs related specifically to digital device screen viewing”. Digital eye strain prevalence of up to 97% has been reported, due to no previously agreed definition/diagnostic criteria and limitations of current questionnaires which fail to differentiate such symptoms from those arising from non-digital tasks. Objective signs such as blink rate or critical flicker frequency changes are not ‘diagnostic’ of digital eye strain nor validated as sensitive. The mechanisms attributed to ocular surface disease exacerbation are mainly reduced blink rate and completeness, partial/uncorrected refractive error and/or underlying binocular vision anomalies, together with the cognitive demand of the task and differences in position, size, brightness and glare compared to an equivalent non-digital task. In general, interventions are not well established; patients experiencing digital eye strain should be provided with a full refractive correction for the appropriate working distances. Improving blinking, optimizing the work environment and encouraging regular breaks may help. Based on current, best evidence, blue-light blocking interventions do not appear to be an effective management strategy. More and larger clinical trials are needed to assess artificial tear effectiveness for relieving digital eye strain, particularly comparing different constituents; a systematic review within the report identified use of secretagogues and warm compress/humidity goggles/ambient humidifiers as promising strategies, along with nutritional supplementation (such as omega-3 fatty acid supplementation and berry extracts)

An Investigation of Computer Vision Syndrome with Smart Devices

The overarching theme of the thesis was to investigate the association between smart device use and computer vision syndrome. The initial study designed and developed the Open Field Tear film Analyser (OFTA) enabling a continuous, real-time assessment of the tear film and blink characteristics during smart device use. The monocular OFTA prototype was validated and showed good intra- and inter-observer repeatability relative to the Oculus Keratograph 5M and Bausch and Lomb one position keratometer. Subsequently, tear osmolarity following engagement with reading and gaming tasks on smart device and paper platforms was investigated. Discrete measures of osmolarity pre- and post-engagement with the tasks were obtained with the TearLab osmometer; osmolarity values differed between platforms when participants were engaged in a gaming task but no such difference was observed with the reading task. In addition, the influence of repeated measurements on tear osmolarity was also explored. To simulate the habitual binocular viewing conditions normally associated with smart device use, the binocular OFTA was developed. The device was used to assess the tear film and blink characteristics whilst engaging with reading and gaming tasks on smart device and paper platforms. The results revealed differences in blink characteristics and non-invasive tear break up time between the different platforms and tasks assessed. In addition, the thesis also reports on an investigation examining the real-time accommodative response to various targets displayed on smart devices using an open-field autorefractor with a Badal lens system adaptation. The results showed that accommodative latency, accommodative lag, mean velocity of accommodation, speed of disaccommodation and mean velocity of disaccommodation varied across the different platforms. Through the use of validated subjective questionnaires and smartphone apps, the relationship between duration of smartphone use and symptoms of dry eye were examined. The findings of this study demonstrated that longer duration of smartphone and personal computer use were associated with higher risk of dry eyes as indicated by subjective questionnaire outcomes.Ministry of Higher Education, MalaysiaInternational Islamic University Malaysi