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S. Koh, N. Maeda, Y. Hori, T. Inoue, H. Watanabe, Y. Hirohara, T. Mihashi, T. Fujikado, Y. Tano; Serial Measurements of Higher-Order Aberrations After Blinking in Subjects With Short Tear Film Break-Up Time. Invest. Ophthalmol. Vis. Sci. 2007;48(13):419.
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To investigate sequential changes in optical quality after blinking in subjects with short tear film break-up time (short BUT).
Ten subjects included in the study had short BUT (<5 seconds) without fluorescein staining of the ocular surface by slit-lamp examination and no signs of tear-deficient dry eye based on the Schirmer I test. Higher-order aberrations (HOAs) were measured sequentially for 30 seconds using a wavefront sensor. During the measurements, subjects were forced to blink every 10 seconds. The aberration data from the central 4 mm were analyzed for coma-like, spherical-like, and total HOAs up to the 6th-order Zernike polynomials. We calculated the stability index (defined as the slope of the linear regression line of the total ocular HOAs between blinks) according to our previous study.
The average stability index of the HOAs was 0.008 in subjects with a short BUT, which was significantly higher than in the normal groups with stable and small fluctuation patterns (stability index, 0.002) (P<0.001, Wilcoxon rank sum test). In seven subjects with a short BUT, the sequential changes in total HOAs had a sawtooth pattern with a marked upward curve that continued to increase after blinking. The increased total HOAs corresponded well with the pattern in coma-like aberrations and not with the spherical-like aberrations, suggesting that the asymmetric change in tear film thickness might be mainly responsible.
Serial measurements of HOAs showed that subjects with a short BUT might not maintain stable optical quality with suppressed blinking because of unstable tear film, although these individuals cannot be diagnosed as having dry eye because they have normal Schirmer’s test values and negative vital staining of the ocular surface.
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