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K. R. Seger, M. A. Crandall, B.-C. Jiang; Wavefront Aberrations and Change Over Time: First Report of a Longitudinal Study. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2793.
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It is known that ocular wavefront aberrations change over a lifetime; however we have no idea whether they change within a moderate time frame, for example, in several years. In this study we look at the variations from baseline measurements of individual’s wavefront aberrations to measurements made approximately one year later.
Spherical aberration (SA), coma and total higher order aberrations (HOAs) were measured for the right eye of optometry students (age 24-30). A COAS aberrometer was used to measure root mean square (RMS) values in dim room illumination on non-dilated eyes. Only those subjects with pupils 5mm or greater in diameter were analyzed (77 eyes). The measurements were repeated under the same conditions with the same instrument by the same researcher 10-13 months later. Analysis was performed to assess the year to year correlation for the various aberrations.
Aberrations did not show significant change in the one year period. SA, coma and total HOA RMS all showed high correlation at the 0.01 level (Pearson 2-tailed correlation) between the baseline and one year measurements. A paired-samples t-test was conducted to evaluate the effect of time on wavefront measurements. There was statistically no significant difference over time for all of the measured parameters. SA RMS baseline mean was .0514 (SD=.03943), time 2 mean was .0516 (SD=.03941), t(76)=.034. The eta squared statistic was .0000. Coma RMS baseline mean was .1043 (SD=.05690), time 2 mean was .1040 (SD=.06644), t(76)=.039. Eta squared statistic was again .0000. Total HOA RMS baseline mean was .1166 (SD=.04807), time 2 mean was .1161 (SD=.04311), t(76)=.136. Eta squared statistic was .0002. The eta values indicate that time (one year) creates a negligible effect.
SA, coma and total HOA does not appear to change in one year. An extension of the longitudinal time frame is an obvious idea for further study. Measurements will be taken again on this group in one year.
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