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J. K. Portello, C. Chu, M. Rosenfield, J. Benzoni, J. Collier; Computer Vision Syndrome: Hard Copy versus Computer Viewing. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5333.
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Computer vision syndrome (CVS) is a complex of eye and vision problems experienced during or related to computer use. Ocular symptoms may include asthenopia, accommodative and vergence difficulties and dry eye. CVS occurs in up to 90% of computer workers, and given the almost universal use of these devices, it is important to identify whether these symptoms are specific to computer operation, or are simply a manifestation of performing a sustained near-vision task.
This study compared ocular and non-ocular symptoms immediately following a sustained near task. 30 young, visually-normal subjects read text aloud either from a desktop computer screen or a printed hardcopy page at a viewing distance of 50cm for a continuous 20 min period. Identical text was used in the two sessions, which was matched for size and contrast. Additionally, target viewing angle and luminance were similar for the two conditions. Immediately following completion of the reading assignment, subjects completed a written questionnaire relating to their level of ocular and general discomfort during the task.
Symptoms were reported on a scale from 1 (very mild) to 10 (very severe). When comparing the computer and hardcopy conditions, significant differences in mean ocular symptom scores were reported with regard to blurred vision during the task (3.53 v 2.28; p=0.006) and dry eye (3.33 v 2.43; p=0.05). In both cases, symptoms were higher during computer use. However, no significant differences were observed between the two tasks in relation to blurred distance vision after nearwork, focusing difficulties, eyestrain, headache, light sensitivity or the eyes feeling irritated, uncomfortable or tired. Additionally, significant differences in non-ocular symptoms relating to discomfort in the elbow, hand/wrist and fingers were also observed, with the computer condition being worse in all these categories.
Symptoms following sustained computer use are significantly worse than those reported after hard copy fixation under similar viewing conditions. A better understanding of the physiology underlying CVS is critical to allow more accurate diagnosis and treatment. This will enable practitioners to optimize patient's visual comfort and efficiency during computer operation.
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