June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Quantifying crystalline lens geometry and optical properties by combined optical coherence tomography & laser ray tracing
Author Affiliations & Notes
  • Ashik Mohamed
    Ophthalmic Biophysics, L V Prasad Eye Institute, Hyderabad, Telangana, India
    School of Optometry and Vision Science, The University of New South Wales, Sydney, New South Wales, Australia
  • Marco Ruggeri
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
  • Eduardo Martinez-Enriquez
    Visual Optics and Biophotonics Lab, Institute of Optics, Consejo Superior de Investigaciones Científicas, Madrid, Spain
  • Pablo Perez-Merino
    Visual Optics and Biophotonics Lab, Institute of Optics, Consejo Superior de Investigaciones Científicas, Madrid, Spain
  • Siobhan Williams
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
    Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida, United States
  • Yue Yao
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
    Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida, United States
  • Bianca Maceo Heilman
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
    Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida, United States
  • Alberto De Castro
    Visual Optics and Biophotonics Lab, Institute of Optics, Consejo Superior de Investigaciones Científicas, Madrid, Spain
  • Virender Singh Sangwan
    Ophthalmic Biophysics, L V Prasad Eye Institute, Hyderabad, Telangana, India
  • Robert C Augusteyn
    School of Optometry and Vision Science, The University of New South Wales, Sydney, New South Wales, Australia
    Vision Cooperative Research Centre, Brien Holden Vision Institute, Sydney, New South Wales, Australia
  • Jean-Marie A Parel
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
    Vision Cooperative Research Centre, Brien Holden Vision Institute, Sydney, New South Wales, Australia
  • Arthur Ho
    School of Optometry and Vision Science, The University of New South Wales, Sydney, New South Wales, Australia
    Vision Cooperative Research Centre, Brien Holden Vision Institute, Sydney, New South Wales, Australia
  • Susana Marcos
    Visual Optics and Biophotonics Lab, Institute of Optics, Consejo Superior de Investigaciones Científicas, Madrid, Spain
  • Fabrice Manns
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
    Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida, United States
  • Footnotes
    Commercial Relationships   Ashik Mohamed, None; Marco Ruggeri, None; Eduardo Martinez-Enriquez, None; Pablo Perez-Merino, None; Siobhan Williams, None; Yue Yao, None; Bianca Maceo Heilman, None; Alberto De Castro, None; Virender Sangwan, None; Robert Augusteyn, None; Jean-Marie Parel, None; Arthur Ho, None; Susana Marcos, None; Fabrice Manns, None
  • Footnotes
    Support  NIH R01EY021834, R01EY014225 and P30EY14801, the Australian Federal Government CRC Scheme through the Vision Cooperative Research Centre, Florida Lions Eye Bank, Research to Prevent Blindness, Drs KR Olsen and ME Hildebrandt, Drs Raksha Urs and Aaron Furtado, Henri and Flore Lesieur Foundation (JMP), Hyderabad Eye Research Foundation, European Research Council ERC-AdG 294099 and CSIC iCoop Program.
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 2715. doi:
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    • Get Citation

      Ashik Mohamed, Marco Ruggeri, Eduardo Martinez-Enriquez, Pablo Perez-Merino, Siobhan Williams, Yue Yao, Bianca Maceo Heilman, Alberto De Castro, Virender Singh Sangwan, Robert C Augusteyn, Jean-Marie A Parel, Arthur Ho, Susana Marcos, Fabrice Manns; Quantifying crystalline lens geometry and optical properties by combined optical coherence tomography & laser ray tracing. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2715.

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

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Abstract

Purpose : To quantify geometry and optical properties of crystalline lenses ex vivo by using a combined optical coherence tomography (OCT) & laser ray tracing (LRT) system.

Methods : 3-D OCT images (Fig 1A) of ex vivo crystalline lenses (maximally stretched with a motorized lens stretcher in a tissue chamber filled with BSS) of a 4.2 y/o cynomolgus monkey were acquired using a commercial SD-OCT (Bioptigen Inc.) coupled to a custom delivery system designed for on- and off-axis imaging. Custom algorithms for image segmentation and distortion correction were applied to quantify lens shape (Fig 1B). Assuming a constant index of refraction for the lens (n=1.420@880nm), computational ray tracing (Zemax) was applied to the OCT-based lens model to predict on-axis and off-axis aberrations. A custom LRT system used the OCT unit for light delivery and a CMOS camera mounted on motorized stages below the lens acquired the spots at different axial positions. A program was developed to calculate ray slopes from the spot positions, which enabled to calculate Zernike wavefront coefficients using a least square curve fitting algorithm. Measured and predicted lens aberrations were compared to assess the impact of lens shape on aberrations and quantify the contribution of lens gradient refractive index (GRIN).

Results : Fig 2 summarizes the image analysis results. LRT-based lens aberrations were dominated by astigmatism (1.64/1.74 µm, 23%/20%), spherical aberration (0.42/0.82 µm, 5%/8%) and coma (1.53/1.34 µm, 22%/19%), on-axis/off-axis (20°) respectively for 6-mm pupils. The simulated aberration terms overestimated the LRT-measured ones by a factor of 1.41/1.47 (astigmatism), 1.31/1.45 (spherical) and 1.09/1.86 (coma) on-axis/off-axis.

Conclusions : LRT-OCT can be utilized to characterize the geometrical and optical properties of the crystalline lens ex vivo. Shape and GRIN both contribute to the optical aberrations of the lens. GRIN has a compensatory role on the spherical aberration of the lens and attenuates the impact of high order aberrations off-axis. Combined information of lens shape and optical aberrations at different angles can be used to reconstruct GRIN.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Fig 1: A. OCT image acquired on one of the two lenses which was oriented with posterior surface (up) facing the beam. B. OCT-based anterior (purple) and posterior (blue) lens surfaces reconstruction.

Fig 1: A. OCT image acquired on one of the two lenses which was oriented with posterior surface (up) facing the beam. B. OCT-based anterior (purple) and posterior (blue) lens surfaces reconstruction.

 

Fig 2: Biometry of stretched cyno lenses

Fig 2: Biometry of stretched cyno lenses

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