Influence of shape and gradient refractive index in the accommodative changes of spherical aberration in nonhuman primate crystalline lenses.
Alberto de Castro,Judith Birkenfeld,Bianca Maceo,Fabrice Manns,Esdras Arrieta,Jean-Marie A. Parel,Susana Marcos +6 more
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TLDR
The reconstructed GRIN lens has more negative spherical aberration and a larger shift toward more negative values with accommodation, compared with the lens with the homogeneous equivalent refractive index.Abstract:
PURPOSE. To estimate changes in surface shape and gradient refractive index (GRIN) profile in primate lenses as a function of accommodation. To quantify the contribution of surface shape and GRIN to spherical aberration changes with accommodation. METHODS. Crystalline lenses from 15 cynomolgus monkeys were studied in vitro under different levels of accommodation produced by a stretching system. Lens shape was obtained from optical coherence tomography (OCT) cross-sectional images. The GRIN was reconstructed with a search algorithm using the optical path measured from OCT images and the measured back focal length. The spherical aberration of the lens was estimated as a function of accommodation using the reconstructed GRIN and a homogeneous refractive index. RESULTS. The lens anterior and posterior radii of curvature decreased with increasing lens power. Both surfaces exhibited negative asphericities in the unaccommodated state. The anterior surface conic constant shifted toward less negative values with accommodation, while the value of the posterior remained constant. GRIN parameters remained constant with accommodation. The lens spherical aberration with GRIN distribution was negative and higher in magnitude than that with a homogeneous equivalent refractive index (by 29% and 53% in the unaccommodated and fully accommodated states, respectively). Spherical aberration with the equivalent refractive index shifted with accommodation toward negative values (� 0.070 lm/diopter [D]), but the reconstructed GRIN shifted it farther (� 0.124 lm/ D). CONCLUSIONS. When compared with the lens with the homogeneous equivalent refractive index, the reconstructed GRIN lens has more negative spherical aberration and a larger shift toward more negative values with accommodation.read more
Citations
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Measurement of Monochromatic Ocular Aberrations of Human Eyes as a Function of Accommodation by the Howland Aberroscope Technique
David A. Atchison,Michael J. Collins,Christine F. Wildsoet,James Christensen,Michael D. Waterworth +4 more
TL;DR: In this article, the effect of accommodation on the monochromatic aberration of the right eye of 15 subjects was investigated using the objective version of the Howland and Howland method.
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The physiological optics of the lens.
TL;DR: Water transport is emerging as the critical parameter that links the transparency and refractive properties of the lens at the cellular level, and highlights the need to study how age-related changes in water transport result in presbyopia and cataract, the leading causes of refractive error and blindness in the world today.
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OCT-based full crystalline lens shape change during accommodation in vivo.
TL;DR: The full shape of the accommodating crystalline lens was estimated using custom three-dimensional (3-D) spectral OCT and image processing algorithms and the lens peripheral region was estimated with a trained and validated parametric model.
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Whole eye axial biometry during accommodation using ultra-long scan depth optical coherence tomography
Jianguang Zhong,Aizhu Tao,Zhe Xu,Zhe Xu,Hong Jiang,Yilei Shao,Yilei Shao,Huicheng Zhang,C.–Y. Liu,Jianhua Wang +9 more
TL;DR: In this paper, the authors investigated changes of axial biometry during accommodation using ultra-long scan depth optical coherence tomography (UL-OCT) and found that axial length of the whole eye changed significantly.
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Refractive and Biometric Changes During Edinger-Westphal Stimulated Accommodation in Rhesus Monkeys
TL;DR: In this paper, the relationship between dynamic accommodative refractive and biometric (lens thickness (LT), anterior chamber depth (ACD), and anterior segment length (ASL)) changes during Edinger-Westphal stimulated accommodation in rhesus monkeys.
References
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Presbyopia and the optical changes in the human crystalline lens with age
TL;DR: It is shown that there are substantial optical changes in the human lens with increasing age and during accommodation, since both the magnitude and the sign of the spherical aberration change with age and stretching.
Journal Article
Age-related changes in human ciliary muscle and lens: a magnetic resonance imaging study.
TL;DR: The theory that presbyopia is actually the loss in ability to disaccommodate due to increases in lens thickness, the inward movement of the ciliary ring, or both is supported.
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The shape of the aging human lens: curvature, equivalent refractive index and the lens paradox.
TL;DR: The aspheric curvature of the lens was measured of 102 subjects ranging in age between 16 and 65 years and the absolute value for the radius of the anterior and posterior lens surface was significantly smaller than previous studies using Scheimpflug photography.
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Change in shape of the aging human crystalline lens with accommodation
TL;DR: The results show that during accommodation there is a decrease in both the anterior and the posterior radius of the lens, although the change in mm per diopter of the latter is much smaller, and an increase in the equivalent refractive index during accommodation was determined.