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    Glare behind computers activates neck muscles

    Reading a computer screen with background glare can affect muscles not only in the eyes but also the neck, according to researchers.

    Their randomised controlled trial “indicates that exposure to direct glare affects the trapezius muscle, possibly by an interaction between the visual system, sympathetic nervous system, and head-stabilising muscles,” wrote Randi Mork of the University College of Southeast Norway in Kongsberg, Norway, and colleagues.

    The finding, published in Optometry and Vision Science, could help in the design and organisation of offices and work stations.

    Previous studies have established that computer work can cause discomfort in the eyes, neck, and shoulders, and a correlation among these symptoms.

    Recent: New study finds association between myopic progression and reading position

    Relative to viewing objects far away, looking at a computer screen creates a higher workload for both smooth and cross-striated muscles in and around the eyes.

    And, when natural visual scanning changes from dynamic motions of vergence and accommodation into static activity, the risk of ocular fatigue increases. Likewise, muscles in the neck take part in active gaze stabilisation.

    Glare affects the accommodation response, and can increase visual discomfort and affect reading performance.

    To see how glare affects muscles in the neck and scapular area, the researchers recruited 15 healthy students with normal vision from the Department of Optometry and Visual Science at University College of Southeast Norway.

    Twelve of the students were female. They ranged in age from 19 to 25 years, and had used computers for a mean of 11 years.

    The researchers excluded people with chronic neck pain, dyslexia, chronic disease, and regular use of medications affecting circulation, pain sensation, vision, or visual comfort. The patients’ mean LogMAR distance visual acuity was -0.16. The eight who had prescription contacts or glasses wore them for the study.

    The researchers assigned the patients to read a text on a computer screen during two different conditions: 30 minutes in an optimum workplace environment and 30 minutes exposed to direct glare. The order of these sessions was determined with the flip of a coin.

    Each session started with a 1-minute rest and was followed by a 5-minute break afterward.

    The researchers asked the patients to sit in a normal upright position and optimised their sitting positions according to international recommendations. To keep the trapezius muscle as relaxed as possible, the patients rested their forearms on supports. The table height was above the elbow height when the paients were seated.

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