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Howard C. Howland, Toshifumi Mihashi, Richa Sharma; Compensation of monochromatic aberrations in older human eyes. Journal of Vision 2006;6(13):51. doi: 10.1167/6.13.51.
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Purpose. We wished to verify and characterize the nature of the compensation of corneal and high order aberrations of the eye by its internal optics as a function of age.
Methods. The corneal and total wave aberrations of 22 subjects whose refraction was within –4.5 +2.4 D spherical equivalent, and whose mean age was 49.7 ± 16.5 SD years were measured using a Topcon Wave-Front Analyzer. 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 aging population (divided into 2 groups < or > 50 years of age) to see if internal aberrations had compensated the corneal aberrations, as indicated by an absolute value of the total aberration coefficient being less than the absolute value of the corneal aberration coefficient. We also examined the correlation between the magnitudes of the corneal aberration and its compensation.
Results. Corneal oblique astigmatism, horizontal coma, and spherical aberration were compensated by the internal optics of the eye. Subjects <50 yrs. had significantly more compensation compared with subjects over 50. The average total higher-order RMS deviation from a perfect wavefront increased with age (p=.0016).
Conclusions. Corneal oblique astigmatism, horizontal coma and spherical aberration are compensated for by the internal optics of the eye, but these compensations decrease with age. We did not find evidence for an individual, magnitude-dependent compensative process for oblique astigmatism; however we did find some for horizontal coma and spherical aberration.
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