Abstract
Purpose: :
Computer vision syndrome (CVS) is a complex of eye and vision problems experienced during or related to computer use. While this condition occurs in up to 90% of computer users, questions remain regarding its underlying etiology. For example, while changes in either accommodation or vergence have been suggested as causative factors, there is little evidence to support such a claim. The aims of the present study were to determine whether subjects with CVS have abnormal accommodative or vergence facility findings, and to identify whether computer use produces a significant change in either of these oculomotor parameters.
Methods: :
25 young subjects were required to read text from a desktop computer screen at a viewing distance of 50cm for a continuous 25 min period. Both before and immediately after the computer task, monocular and binocular accommodative facility and vergence facility were measured using ±2.00D lens and 12Δ base-out / 3Δ base-in prism flippers, respectively over a 60s period. At the end of the experimental session, subjects completed a written questionnaire concerning their level of ocular and general discomfort during the computer task.
Results: :
Mean pre-task values of monocular and binocular accommodative facility and vergence facility were 11.0, 8.3 and 11.4 cycles per minute, respectively. No significant change in any of these parameters was observed following the computer task. While there was a trend for both pre- and post-task vergence facility to be correlated with the total ocular symptom score, this narrowly failed to reach significance (p = 0.06 and 0.08, respectively). However, when considering the most prevalent ocular symptoms reported, namely tired eyes, dry eye and eyestrain, there was a significant positive correlation between pre-task vergence facility and both tired eyes (r = 0.47; p = 0.03) and eyestrain (r = 0.44; p = 0.04). In each case, subjects having higher pre-task vergence facility reported the most severe ocular CVS symptoms.
Conclusions: :
CVS was greater in subjects having higher levels of pre-task vergence facility. We hypothesize that symptoms may be related to greater ocular instability during computer use. However, computer work did not produce any significant change in accommodative or vergence facility, and no significant correlation was observed between accommodative facility and CVS.
Keywords: vergence • accomodation • quality of life