The Effects of Visual Display Distance on Eye Accommodation, Head Posture, and Vision and Neck Symptoms

Ergonomics Program, University of California Berkeley, 1301 South 46th St., Bldg. 163, Richmond, CA 94804, USA.
Human Factors The Journal of the Human Factors and Ergonomics Society (Impact Factor: 1.69). 11/2007; 49(5):830-8. DOI: 10.1518/001872007X230208
Source: PubMed


Determine the effects of display viewing distance on both the visual and musculoskeletal systems while the text height is held constant across viewing distances.
The distance from the eyes to a computer display may affect visual and neck comfort. If the angular size of the characters remains the same, it is recommended that the display be placed at a farther viewing distance (e.g., 70-100 cm). However, in common usage, the character sizes are not adjusted based on viewing distance.
Participants under the age of 35 years (N = 24) performed visually demanding tasks using a computer display for 2 hr each at three viewing distances (mean: 52.4, 73.0, and 85.3 cm) while torso and head posture were tracked. At the end of each task, eye accommodation was measured and symptoms were recorded.
The near distance was associated with significantly less blurred vision, less dry or irritated eyes, less headache, and improved convergence recovery when compared with the middle and far distances. Participants moved their torsos and heads closer to the monitor at the far distance.
If the computer screen character sizes are close to the limits of visual acuity, it is recommended that the computer monitor be positioned between the near (52 cm) and middle (73 cm) distance from the eyes.
The location of a computer display should take into account the size of the characters on the screen and the visual acuity of the user.

Download full-text


Available from: David Rempel, May 02, 2014
1 Follower
58 Reads
  • Source
    • "Other studies have shown that most users prefer viewing distances from 63cm to 85cm (Grandjean et al., 1983; Hennings and Ye, 1996; Jaschinski et al., 1998; Rempel et al., 2007). Compared with desktop, laptop and tablet computers, previous studies have reported that users had to lean forward and adopted decreased viewing distances when using smaller-sized computers (Shin and Hegde, 2010; Szeto and Lee, 2002). "
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents an overview of global ergonomics standards and guidelines for design of computer workstations, with particular focus on their inconsistency and associated health risk impact. Overall, considerable disagreements were found in the design specifications of computer workstations globally, particularly in relation to the results from previous ergonomics research and the outcomes from current ergonomics standards and guidelines. To cope with the rapid advancement in computer technology, this article provides justifications and suggestions for modifications in the current ergonomics standards and guidelines for the design of computer workstations. PRACTITIONER SUMMARY A research gap exists in ergonomics standards and guidelines for computer workstations. We explore the validity and generalizability of ergonomics recommendations by comparing previous ergonomics research through to recommendations and outcomes from current ergonomics standards and guidelines.
    Ergonomics 07/2015; DOI:10.1080/00140139.2015.1076528 · 1.56 Impact Factor
  • Source
    • "The subject of inquiry of this study is to outline health effects of visual–musculoskeletal interactions that may arise during strenuous near work and to provide testable hypotheses for future research. Professional use of modern instruments of Information or Communication Technology (ICT) is linked with eye–neck/scapular area problems (Treaster et al. 2006; Rempel et al. 2007; Wiholm et al. 2007; Helland et al. 2008; Torii et al. 2008; Ukai and Howarth 2008; Tornqvist et al. 2009). Understanding the causes of these lingering work–environment problems remains a major scientific goal (Lie and Watten 1987; Franzén et al. 2000; Piccoli 2003; Sjøgaard et al. 2006; Mathiassen 2006; Strøm et al. 2009). "
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this experimental study was to investigate if sustained periods of oculomotor load impacts on neck/scapular area muscle activity. The static trapezius muscle activity was assessed from bipolar surface electromyography, normalized to a submaximal contraction. Twenty-eight subjects with a mean age of 29 (range 19-42, SD 8) viewed a high-contrast fixation target for two 5-min periods through: (1) -3.5 dioptre (D) lenses; and (2) 0 D lenses. The target was placed 5 D away from the individual's near point of accommodation. Each subject's ability to compensate for the added blur was extracted via infrared photorefraction measurements. Subjects whose accommodative response was higher in the -D blur condition (1) showed relatively more static bilateral trapezius muscle activity level. During no blur (2) there were no signs of relationships. The results indicate that sustained eye-lens accommodation at near, during ergonomically unfavourable viewing conditions, could possibly represent a risk factor for trapezius muscle myalgia.
    Arbeitsphysiologie 01/2011; 111(1):29-36. DOI:10.1007/s00421-010-1629-x · 2.19 Impact Factor
  • Source
    • "However, there is anatomical, pharmacological and physiological evidence for an additional sympathetic input – via adrenoceptors [1,2]. From a human factors perspective, measurements of accommodation can be relevant for two reasons: first, the design of complex visual displays (for example, virtual image displays) may include conditions, where the accommodative response is not appropriate or mislead, i.e. blurred vision may result [3,4]. This question is complicated by the fact that accommodation is affected by factors like contrast, blur or perceived distance [5]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of the present study was to assess accommodation as a possible indicator of changes in the autonomic balance caused by altered cognitive demand. Accounting for accommodative responses from a human factors perspective may be motivated by the interest of designing virtual image displays or by establishing an autonomic indicator that allows for remote measurement at the human eye. Heart period, pulse transit time, and the pupillary response were considered as reference for possible closed-loop accommodative effects. Cognitive demand was varied by presenting monocularly numbers at a viewing distance of 5 D (20 cm) which had to be read, added or multiplied; further, letters were presented in a "n-back" task. Cardiovascular parameters and pupil size indicated a change in autonomic balance, while error rates and reaction time confirmed the increased cognitive demand during task processing. An observed decrease in accommodation could not be attributed to the cognitive demand itself for two reasons: (1) the cognitive demand induced a shift in gaze direction which, for methodological reasons, accounted for a substantial part of the observed accommodative changes. (2) Remaining effects disappeared when the correctness of task processing was taken into account. Although the expectation of accommodation as possible autonomic indicator of cognitive demand was not confirmed, the present results are informative for the field of applied psychophysiology noting that it seems not to be worthwhile to include closed-loop accommodation in future studies. From a human factors perspective, expected changes of accommodation due to cognitive demand are of minor importance for design specifications - of, for example, complex visual displays.
    Journal of Negative Results in BioMedicine 09/2008; 7(1):6. DOI:10.1186/1477-5751-7-6 · 1.47 Impact Factor
Show more