Computer Work Station Ergonomics John Hayes and Jim Sheedy Purpose: To study the effects of computer use on reported visual and physical symptoms and to measure the effects upon quality of life measures. Methods: A survey of 1000 university employees (70.5% adjusted response rate) assessed visual and physical symptoms, job physical and mental demands, ability to control/influence work, amount of work at a computer, computer work environment, relations with others at work, life and job satisfaction, and quality of life. Data were analyzed to determine whether self-assessment of eye symptoms can affect opinions of quality of life. The study also explored the factors that are associated with eye symptoms. Structural equations and multiple regression were used to assess the hypotheses. Results: 70% of the employees used some form of vision correction during computer use, 2.9% used glasses specifically prescribed for computer use, and 8% had had refractive surgery. Sampled employees spent an average of 6 hours per day at the computer. In a multiple regression framework, blur and eyestrain (and the composite variable eye symptoms) were significantly associated with a composite quality of life variable (p<.001) after adjusting for job quality, job satisfaction, supervisor relations, co-worker relations, mental and physical load of the job, and job demand (adjusted R2 = 0.91). Age and gender were not significantly associated with symptoms. In the structural model eye symptoms were significantly affected by job demand and lighting, but not hours of computer use or use of computer glasses. 33% of the sample agreed that shielding their eyes to block over head light in their work place improved visual comfort. Conclusions: Eye symptoms can significantly impact quality of life in the work environment. Reduction of eye symptoms and perhaps an increase in quality of life may be achieved by eliminating overhead glare. Abstract Objectives Can a simple survey detect computer using employees with vision problems? Are the vision problems associated with factors amenable to remediation? General Approach Construct a model of work place satisfaction Include factors that cause vision problems Include factors that vision problems cause Control for work place social environment Test the model with a mail out survey Design and Analysis Cross-sectional design Structural Equation analysis Procedure Mail-out survey through campus mail Sent to 1000 Ohio State University employees in 29 Colleges and Offices with more than 75 employees. 4 mailings. Complete mailing, postcard follow-up, Second mailing to non-responders, postcard follow-up. Demographics and Response Rate 70.5% response rate Age range % female Computer use: 6 hrs/day (2.3SD) ` Life Quality Physical Symptoms Eye Symptoms Survey Questions Bars represent individual correlations with quality of life Bars are presented in the order they were entered into the equation. R squared values represent the additional variance accounted for by the factors as variable blocks are stepped in. Quality of life is not a function of age or gender Job characteristics and social environment accounted for most of the quality of life variance Eye symptoms had a small but significant contribution to the quality of life after adjusting for all the other variables Blue bars represent simple correlations with the physical symptom latent variable. Red bars indicate the partial correlations. The bars are ordered based on forced entry into the model The R squared values identify the additional contribution of variance by the block of variables grouped by the lines above the bars Vision symptom latent variable was the most associated with physical symptoms even after accounting for other types of variability Ergonomic considerations significantly reduced physical symptoms Gender and the number of hours at the computer were not significant after other factors were added to the model Job Demand was a significant contributor to eye symptoms Clearly lighting was the major contributor to eye symptom variance of the variables measured 59% of respondents said there were bright overhead lights or bright windows in the field of vision while looking at the computer display. Of those, 56% said putting their hand over their eyes helped. Eye and physical symptoms parallel the various ergonomic factors The most effective work station symptom relief variables include lower back support, a comfortable chair, a clear display, and the display at eye level. Ergonomic Factors To what extent do you experience…..? NoneSlightMildModerateSomewhat Bad BadSevere Blurred vision at near distances, e.g. book or newspaper (with your usual glasses or contact lenses) Blurred vision at intermediate distances, e.g. computer screen (with your usual glasses or contact lenses) Blurred vision at far distances, e.g. driving (with usual glasses or contact lenses) Difficulty or slowness in refocusing my eyes from one distance to another Irritated or burning eyes Dry eyes Eyestrain Headache Tired eyes Sensitivity to bright lights To what extent do you experience discomfort in your: NoneSlightMildModerate Somewhat Bad BadSevere Neck Shoulder Elbow/Forearm Hand/Wrist Fingers Upper Back Lower Back Thighs/Knees Lower Leg Ankle/Foot Eyes We would like to know about any work-related discomfort that you may experience Please circle the word that best describes your level of discomfort at the end of a typical workday for each symptom or body part listed. Section II: Your job Now, we’d like to ask you about various aspects of your job. For the questions below, please circle the most appropriate response. Strongly Disagree Moderately Disagree Slightly Disagree Neither Agree/Disagree Slightly Agree Moderately Agree Strongl y Agree My job requires that I learn new things My job involves a lot of repetitive work My job requires me to be creative My job allows me to make a lot of decisions on my own My job requires a high level of skill I have very little freedom to decide how I do my work I have very little freedom to decide how I do my work I get to do a variety of different things on my job I have a lot of say about what happens on my job I have an opportunity to develop my special abilities My job requires working very fast My job requires working very hard I am not asked to do an excessive amount of work I have enough time to get the job done I am free from conflicting demands that others make My job requires long periods of intense concentration My tasks are often interrupted before they can be completed My job is very hectic My job requires a great deal of concentration My job requires me to remember many things I must keep my mind on my work at all times I can take it easy and still get my work done I can let my mind wander and still do the work Section III: Computer work Now we are interested in learning if you work with a computer – and, if so, we would like to learn how you use it. Do you work with a computer at work?YESNO If YES, then answer the following questions, if NO, skip to Section IV: Quality of Life Circle the number of hours on an average workday that you use a computer at work? more Circle the number of hours on an average workday that you use a computer at home? more When working at my computer: ___ I do not usually wear glasses or contact lenses ___ I usually wear the same glasses that I wear most of the day if so, what kind? ___ single vision lenses (same power throughout the lens – no lines) ___ progressive lenses (different power in top and bottom, no line) ___ bifocal or trifocal lenses ___ I usually wear reading glasses (e.g. from a drug store) at my computer ___ I usually wear glasses prescribed special for computer work ___ I usually wear contact lenses at my computer ___ I usually wear contact lenses with reading glasses at my computer The center of my computer display is: ____ Higher than my eyes ____ Level with my eyes ____ A few inches (1”-3”) lower than my eyes ____ Somewhat lower (4”-8”) lower than my eyes ____ Much lower (more than 8”) than my eyes Which type of computer do you use most often? ____ Lap top ____ Desk top computer with a CRT display (like a TV screen – almost as deep as it is tall) ____ Desk top computer with a flat panel or LCD display (thin monitor) To what extent do you look at other documents (for example, data entry of items from a form or obtaining other information from hard copy documents) when working at the computer? NeverAlmost Never SometimesFairly Often To what extent do you look at the keyboard when working at the computer? NeverAlmost Never SometimesFairly Often My keyboard is: ____ At the same height as my desk surface ____ Lower than a typical desk height (e.g. keyboard tray) When working at my computer the computer display is straight in front of my body Strongly Disagree Moderately Disagree Slightly Disagree Neither Agree/Disagree Slightly Agree Moderately Agree Strongly Agree Are there bright overhead lights or bright windows in your field of vision while looking at your computer display? YES NO If you answered “YES” to bright lights, then please do the following: While looking at your computer display, block the bright lights with your hand (as shown in the picture). Blocking the lights with my hand is noticeably more comfortable. Strongly Disagree Moderately Disagree Slightly Disagree Neither Agree/Disagree Slightly Agree Moderately Agree Strongly Agree I can see my computer display very clearly (while wearing my glasses and/or contact lenses) Strongly Disagree Moderately Disagree Slightly Disagree Neither Agree/Disagree Slightly Agree Moderately Agree Strongly Agree My back, especially the lower back, is comfortably supported while I work at the computer Strongly Disagree Moderately Disagree Slightly Disagree Neither Agree/Disagree Slightly Agree Moderately Agree Strongly Agree I use armrests on the chair to help support my arms while typing and mousing at the computer Strongly Disagree Moderately Disagree Slightly Disagree Neither Agree/Disagree Slightly Agree Moderately Agree Strongly Agree The chair I use at the computer is comfortable Strongly Disagree Moderately Disagree Slightly Disagree Neither Agree/Disagree Slightly Agree Moderately Agree Strongly Agree How often do you typically take a break from working at your computer? I am frequently up and down from my computer Every half hour Every hour Every 2 hours Every 4 hours Section IV: Quality of Life Now we would like to know more about your general feelings towards work and life. Instructions: These questions ask you about your feelings and thoughts during the last month. In each case, circle how often you felt or thought a certain way. NeverAlmost Never SometimesFairly Often Very Often In the last month, how often have you been upset because of something that happened unexpectedly? In the last month, how often have you felt that you were unable to control the important things in your life? In the last month, how often have you felt nervous and "stressed"? In the last month, how often have you felt confident about your ability to handle your personal problems? In the last month, how often have you felt that things were going your way? In the last month, how often have you found that you could not cope with all the things that you had to do? In the last month, how often have you been able to control irritations in your life? In the last month, how often have you felt that you were on top of things? In the last month, how often have you been angered because of things that were outside of your control? In the last month, how often have you felt difficulties were piling up so high that you could not overcome them? Please mark which of the words best describes your life. If your life is somewhere in between, please circle the number. Is your life: Boring Interesting Is your life: Enjoyable Miserable Is your life: Worthwhile Useless Is your life: Friendly Lonely Is your life: Full Empty Is your life: Hopeful Discouraging Is your life: Rewarding Disappointing Your life: Brings out the best in you Doesn’t give you much chance Now we would like to know more about your general feelings about work and those you work with Strongly Disagree Moderately Disagree Slightly Disagree Neither Agree/Disagree Slightly Agree Moderately Agree Strongly Agree People I work with are competent in doing their jobs People I work with take a personal interest in me I am exposed to hostility or conflict from the people I work with People I work with are friendly The people I work with encourage each other to work together People I work with are helpful in getting the job done If you have a supervisor then answer the next five questions Strongly Disagree Moderately Disagree Slightly Disagree Neither Agree/Disagree Slightly Agree Moderately Agree Strongly Agree My supervisor is concerned about the welfare of those under him My supervisor pays attention to what I am saying I am exposed to hostility or conflict from my supervisor My supervisor is helpful in getting the job done My supervisor is successful in getting people to work together How satisfied are you with your job Not at allNot tooSomewhatVery Would you advise a friend to take this job Advise against Have doubts about Strongly recommend Would you take this job again Take without hesitation Have second thoughts Definitely not How likely is it that you will find a new job in the next year? Very LikelySomewhatNot at all Is this job like what you wanted when you applied for it? Very MuchSomewhat like Not very much like Have you had surgery (refractive surgery) on your eyes to reduce your dependence on glasses or contact lenses (e.g. LASIK or radial keratotomy)? Yes No During the past month, other than your regular job, did you participate in any physical activities or exercises such as running, calisthenics, golf, gardening, or walking for exercise? Never Seldom Sometimes (at least once or twice a week for 30 minutes) Usually (at least three times a week for 30 minutes or more) Very Often (more than three times a week for 30 minutes or more What is your age? __ years What is your gender?MaleFemale Thank you for taking the time to assist us with this survey. The results will be shared with the Administration to hopefully improve working conditions at the University. 1.Hayes JR, Sheedy JE, Stelmack JA, et al. Computer use, symptoms, and quality of life. Optom Vis Sci 2007;84: