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Ramkumar Sabesan, Scott MacRae, Geunyoung Yoon; Role of native spherical aberration in the extended depth of focus. Journal of Vision 2010;10(15):74. doi: 10.1167/10.15.74.
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© ARVO (1962-2015); The Authors (2016-present)
It is well established that an induction of spherical aberration (SA) in an optical system, including the human eye, extends depth of focus (DoF). The purpose of this study was to investigate whether long-term visual experience with one's own native ocular SA influences the DoF when SA is induced artificially. Six eyes with native positive SA (Group 1, 0.40 ± 0.24 μm) and four eyes with native negative SA (Group 2, −0.65±0.45 μm) were employed for the study. Accommodation was paralyzed. Through-focus high contrast visual acuity was measured after correcting all aberrations and imposing each of +0.5μm and −0.5μm SA for a 6-mm pupil using an adaptive optics system in both groups. The focus position for distance vision was first optimized at which visual acuity was best. DoF was determined as the near dioptric range from the best focus for which visual acuity was better than 20/40. In Group 1, larger DoF was observed with +0.5 μm SA induced (2.14±0.24D) than with −0.5 μm SA induced (1.88±0.24D). Similarly, in Group 2, larger DoF was observed with −0.5 μm SA induced (2.27±0.32 D) than with +0.5 μm SA induced (2.04±0.28D). The difference in DoF when inducing positive and negative SA was statistically significant for both cases and tended to be higher when subject's native SA was closer to the induced SA. This might suggest that long-term visual experience with native SA might play an important role in determining the DoF enhancement after inducing SA.
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