May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
The Change of the Equivalent Refractive Index of the Crystalline Lens as a Function of Accommodation Response Measured With Scheimpflug Imaging and Aberrometry
Author Affiliations & Notes
  • M. Dubbelman
    Physics & Medical Technology, Vrije Univ Medical Center, Amsterdam, The Netherlands
  • E. A. Hermans
    Physics & Medical Technology, Vrije Univ Medical Center, Amsterdam, The Netherlands
  • G. L. van der Heijde
    Physics & Medical Technology, Vrije Univ Medical Center, Amsterdam, The Netherlands
  • R. M. Heethaar
    Physics & Medical Technology, Vrije Univ Medical Center, Amsterdam, The Netherlands
  • Footnotes
    Commercial Relationships  M. Dubbelman, None; E.A. Hermans, None; G.L. van der Heijde, None; R.M. Heethaar, None.
  • Footnotes
    Support  The SenterNovem grant IS 043081
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 3775. doi:https://doi.org/
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      M. Dubbelman, E. A. Hermans, G. L. van der Heijde, R. M. Heethaar; The Change of the Equivalent Refractive Index of the Crystalline Lens as a Function of Accommodation Response Measured With Scheimpflug Imaging and Aberrometry. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3775. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : To experimentally verify the suggestion of Gullstrand (1911) hat the equivalent refractive index of the human lens increases with accommodation.

Methods: : For five subjects, the left eye was used to focus at a different accommodation stimulus, while the right eye was imaged using corrected Scheimpflug photography in order to obtain the shape of the lens and cornea during accommodation. Thereafter, the procedure was repeated, but instead of the Scheimpflug imaging, the accommodative response of the right eye was measured objectively with an aberrometer. Finally, the axial length was measured using the Zeiss IOL-master. Combining the results of all these measurements allowed correction of the digital Scheimpflug images for corneal and lenticular refraction and simultaneously calculation of the equivalent refractive index of the lens for all different accommodative stimuli. This equivalent refractive index is based on the assumption that the lens consists of a homogeneous medium with a single refractive index.

Results: : Mean equivalent refractive index (±s.d) was 1.4345±0.008). For all five subjects, there was no significant change in the equivalent refractive index of the lens as a function of accommodation. Furthermore, the accommodative response appeared to be lower than the accommodative stimulus (i.e. accommodative lag).

Conclusions: : Gullstrand suggested that the change of power of the lens needed for accommodation does not result of changes in lens thickness and surface curvature alone, but also from changes in the refractive index distribution within the lens. As a result, there would be an increase in the equivalent refractive index with accommodation. He called this process the intracapsular mechanism of accommodation. However, our results make it clear that the equivalent refractive index of the lens does not change with accommodation when the accommodative lag is taken into account.

Keywords: accomodation • refraction • anterior segment 
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