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J.E. Kelly, T. Mihashi, H.C. Howland; Internal Compensation for Corneal Astigmatism and High Order Aberrations of the Eye . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2553.
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Purpose: We wished to verify and characterize the nature of the compensation of corneal astigmatism and high order aberrations of the eye by its internal optics. Methods: The corneal and total optical wave aberrations of 30 young normal subjects whose mean age was 21.4 ± 4.1 years were measured using a Topcon KR 9000PW Wave-Front Analyzer. For each subject, the Zernike coefficients describing the wave aberration of the internal optics of the eye were computed by subtracting the corneal aberration coefficient from the total ocular coefficient. These were examined across the population to see if internal aberrations had compensated the corneal aberrations, as indicated by smaller mean absolute values of total than corneal aberration coefficients, opposite signs of the corneal and internal coefficients and negative correlations between them. Additionally, angle alpha was estimated using the distance between the center of the subject's pupil and the first Purkinje reflex. Results: It was found that with/against the rule astigmatism was compensated, as were horizontal coma and spherical aberration (Zernike coefficients 5, 8 and 12). Of all coefficients, only a significant negative correlation was found between corneal and internal coefficients of horizontal coma. We also found a significant correlation between the estimates of angle alpha and the magnitude of corneal horizontal coma. Conclusions: Corneal with/against the rule astigmatism, horizontal coma and spherical aberration are compensated for by the internal optics of the eye. We did not find evidence for an individual, developmental compensation process for high order aberrations of the eye.
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