Abstract
Purpose: :
Computer vision syndrome (CVS) is a complex of eye and vision problems related to computer use which has been reported in up to 90% of computer workers. Ocular symptoms may include asthenopia, accommodative and vergence difficulties and dry eye. Previous studies have reported that small uncorrected refractive errors may have a significant impact on symptoms of CVS. However, their effect on task performance has not been determined.
Methods: :
This study recorded symptoms after a sustained period of reading paragraphs of unrelated words from a computer monitor (viewing distance = 50cm) either through the habitual distance refractive correction or with a supplementary -1.00 or -2.00D oblique cylinder added over these lenses in 12 young, visually-normal subjects. Additionally, the distance correction condition (without induced astigmatism) was conducted twice to assess the repeatability of the symptom questionnaire. Subjects’ reading speed and accuracy were monitored during the course of the 10 min trial.
Results: :
There was no significant difference in reading speed (mean speed = 109.9 words/min) or number of errors (mean error rate = 1.09/min) between the 3 astigmatic conditions. However, increasing astigmatism produced a significant rise in symptoms. Mean symptom scores for the 0, 1 and 2D astigmatic conditions were 0.43, 0.97 and 3.20, respectively (p= 0.000). Further, the 95% limits of agreement of the mean symptom score following the repeated zero astigmatism condition was ±1.25.
Conclusions: :
The presence of uncorrected astigmatism produced a significant increase in post-task symptoms but did not affect task performance. The correction of small astigmatic refractive errors may be important in optimizing patient comfort during computer operation.
Keywords: astigmatism • clinical (human) or epidemiologic studies: systems/equipment/techniques • quality of life