Serial Measurements of Higher–Order Aberrations Following Blinking in Normal Subjects

Abstract

Abstract: : Purpose: To investigate the sequential changes in the optical quality of the normal eyes after blinking. Methods: Higher–order aberrations (HOAs) were sequentially measured for 30 seconds in 20 normal subjects with a newly developed wavefront sensor. During the measurement, subjects were forced to blink every 10 seconds. The obtained aberration data were analyzed for the central 4 mm diameter for coma–like, spherical–like, and total HOAs up to the 6^th–order Zernike polynomials. Results:The serial changes of HOAs with blinking were classified into four groups: stable pattern (35%), small fluctuation pattern (35%), saw–tooth pattern (20%), and others that were not classifiable in the three patterns (10%). The fluctuation indexes of the HOAs evaluated by the average of the standard deviation in these four groups were 0.008, 0.013, 0.024, and 0.011, respectively. The saw–tooth pattern had a significantly higher value than the stable pattern and the small fluctuation pattern in fluctuation index (P<0.001, P<0.001, by one–way ANOVA). The stability indexes of the HOAs expressed by the slope of the regression line were 0.001, 0.003, 0.008, and 0.002, respectively. Saw–tooth pattern also had a significantly higher value than the stable and the small fluctuations patterns in the stability index (P<0.001, P<0.001, by one–way ANOVA ). In the saw–tooth group, the increased total HOAs corresponded well with the pattern in coma–like aberrations rather than that with spherical–like aberrations, suggesting that the asymmetric change in tear–film thickness might be mainly responsible. Conclusions: Dynamic changes in HOAs after blinking and forced eye opening for 10 seconds showed variations even in clinically normal subjects. Serial measurements of higher–order aberrations might be useful to evaluate the dynamic changes in tear–film and its effects on the quality of vision after blinking.

Keywords: cornea: tears/tear film/dry eye • refractive surgery: optical quality