Contribution of the gradient refractive index and shape to the crystalline lens spherical aberration and astigmatism.
The optical properties of the crystalline lens are determined by its shape and refractive index distribution. However, to date, those properties have not been measured together in the same lens, and therefore their relative contributions to optical aberrations are not fully understood. The shape, th...
| Publicado en: | Vision Research Vol. 86; pp. 27 - 35 |
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| Autores principales: | , , , , |
| Formato: | research Journal Article |
| Publicado: |
Pergamon Press - An Imprint of Elsevier Science
Jun2013
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ccm&AN=104075836&site=ehost-live header: @attributes: shortDbName: ccm uiTerm: 104075836 longDbName: CINAHL Complete uiTag: AN controlInfo: bkinfo: dissinfo: jinfo: jid: 00426989 2FL jtl: Vision Research issn: 00426989 maglogo: N pubinfo: dt: Jun2013 vid: 86 pid: 2410 pub: Pergamon Press - An Imprint of Elsevier Science artinfo: ui: 104075836 NLM23597582 2012139964 10.1016/j.visres.2013.04.004 NLM23597582 104075836 ppf: 27 ppct: 8 formats: tig: atl: Contribution of the gradient refractive index and shape to the crystalline lens spherical aberration and astigmatism. aug: au: Birkenfeld, Judith de Castro, Alberto Ortiz, Sergio Pascual, Daniel Marcos, Susana affil: Instituto de Optica 'Daza de Valdés', Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid, Spain. Electronic address: j.birkenfeld@csic.es. sug: subj: Lens, Crystalline Physiopathology Refraction, Ocular Refractive Errors Physiopathology Animal Studies Astigmatism Physiopathology Models, Biological Swine Tomography Funding Source ab: The optical properties of the crystalline lens are determined by its shape and refractive index distribution. However, to date, those properties have not been measured together in the same lens, and therefore their relative contributions to optical aberrations are not fully understood. The shape, the optical path difference, and the focal length of ten porcine lenses (age around 6 months) were measured in vitro using Optical Coherence Tomography and laser ray tracing. The 3D Gradient Refractive Index distribution (GRIN) was reconstructed by means of an optimization method based on genetic algorithms. The optimization method searched for the parameters of a 4-variable GRIN model that best fits the distorted posterior surface of the lens in 18 different meridians. Spherical aberration and astigmatism of the lenses were estimated using computational ray tracing, with the reconstructed GRIN lens and an equivalent homogeneous refractive index. For all lenses the posterior radius of curvature was systematically steeper than the anterior one, and the conic constant of both the anterior and posterior positive surfaces was positive. In average, the measured focal length increased with increasing pupil diameter, consistent with a crystalline lens negative spherical aberration. The refractive index of nucleus and surface was reconstructed to an average value of 1.427 and 1.364, respectively, for 633 nm. The results of the GRIN reconstruction showed a wide distribution of the index in all lens samples. The GRIN shifted spherical aberration towards negative values when compared to a homogeneous index. A negative spherical aberration with GRIN was found in 8 of the 10 lenses. The presence of GRIN also produced a decrease in the total amount of lens astigmatism in most lenses, while the axis of astigmatism was only little influenced by the presence of GRIN. To our knowledge, this study is the first systematic experimental study of the relative contribution of geometry and GRIN to the aberrations in a mammal lens. pubtype: Academic Journal doctype: research Journal Article ougenre: Article language: English refInfo: holdings: @attributes: islocal: N |
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