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K. M. Daum, F. M. Zeried; Comparison of Characteristics of Younger and Older Computer Users. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3971.
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The purpose of this study was to determine the extent that groups of young and older adult computer users differed with respect to their use of the computer, refractive status and their self-reported visual and ergonomic conditions.
Subjects were required to use a computer at least one hour per day or more; be either 19 to 35 yrs of age (group A) or 40 yrs of age or older (group B) and have corrected VA of 20/40 or better. Refractive error was assessed via subjective refraction and vector methodology that provided a system to compare orthogonal refractive components (M, spherical; J0, 180/90; and, J45, 45/135) of the distance correction (in vector diopters, VD). All subjects completed questionnaires to assess their use of the computer and their self-reported visual conditions and ergonomic status.
A total of 72 subjects participated (Group A (n=36): 7M, 29F; mean age 27.7 yrs, std dev 4.1, range 21 to 35 yrs; group B (n=36): 6 M, 30F; mean age 50.3 yrs, std dev 2.6, range 40 to 81 yrs; t=-13.7, p=0.0001). Daily estimates of time at the computer was similar between groups (A: 5.1 hrs/day; B: 4.5 hrs/day; p=NS). Rank order estimates of tasks on the computer was similar between the groups with the exception that the older group (B) ranked email higher (A median rank, 3 vs. B median rank, 1; H=11.05, p=0.001). Analysis did not support a hypothesis of differences in self-reported visual conditions (dry eye syndrome, focusing problems, binocular problems and glare) between the groups. Although an overall estimate of self-reported ergonomic problems (desk, chair, monitor, keyboard, mouse and lighting) was not significantly different between the two groups, the older subject group (B) reported more problems with their chair (H=3.90, p=0.048). Subjects in groups A and B demonstrated mean M, J0 and J45 components of their habitual distance correction to be (group A) -3.12, 0.28 and 0.04 and (group B) -0.61, 0.24 and -0.02, respectively. Analyses of best refractive correction mean components (M, J0 and J45) of the two groups were (group A) -3.52, 0.39 and 0.02 and (group B) -0.82, -0.06 and 0.06, respectively. Non-parametric analysis of differences between the habitual and best correction components by group supported hypotheses of differences for M (p=0.0001, 0.0001) and J0 (p=NS, 0.0001) but not J45 (NS, NS). The overall habitual and best correction (VD) of groups A and B were 3.20 and 0.06 ((p=0.0001) and 3.2 and 1.22 (p=0.0001), respectively. The uncorrected habitual refractive error was similar between the two groups.
These data suggest that groups of subjects recruited for these types of clinical trials may not be equivalent in all respects.
Clinical Trial: :
www.clinicaltrials.gov NCT00317525, NCT00318045
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