July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Comparison of curvature-based and biometry-based methods for in vivo crystalline lens power calculation
Author Affiliations & Notes
  • Gabrielle Monterano Mesquita
    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
  • Yu-Cherng Chang
    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
  • Florence Cabot
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
    Anne Bates Leach Eye Hospital, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
  • 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
  • Giovanni Gregori
    Quantitative Imaging Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
  • Arthur Ho
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
    Brien Holden Vision Institute, 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
  • Sonia H Yoo
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
    Anne Bates Leach Eye Hospital, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
  • Jean-Marie Parel
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
    Brien Holden Vision Institute, Sydney, New South Wales, Australia
  • 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   Gabrielle Monterano Mesquita, None; Yu-Cherng Chang, None; Florence Cabot, None; Siobhan Williams, None; Giovanni Gregori, None; Arthur Ho, None; Marco Ruggeri, US Patent 8,425,037 (P); Sonia Yoo, None; Jean-Marie Parel, US Patent 8,425,037 (P); Fabrice Manns, US Patent 8,425,037 (P)
  • Footnotes
    Support  National Eye Institute Grants 1F30EY027162 1R01EY021834, P30EY14801 (Center Grant); Florida Lions Eye Bank and the Beauty of Sight Foundation; Drs KR Olsen and ME Hildebrandt, Drs R Urs and A Furtado; the Henri and Flore Lesieur Foundation (JMP); an unrestricted grant from Research to Prevent Blindness.
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 599. doi:https://doi.org/
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      Gabrielle Monterano Mesquita, Yu-Cherng Chang, Florence Cabot, Siobhan Williams, Giovanni Gregori, Arthur Ho, Marco Ruggeri, Sonia H Yoo, Jean-Marie Parel, Fabrice Manns; Comparison of curvature-based and biometry-based methods for in vivo crystalline lens power calculation. Invest. Ophthalmol. Vis. Sci. 2019;60(9):599. doi: https://doi.org/.

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

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Abstract

Purpose : In vivo crystalline lens power is typically estimated from measurements of ocular distances and refraction (Bennett method) since standard commercial biometry devices do not measure lens curvatures. Lens power can also be calculated directly from measurements of lens thickness and curvatures and an estimate of the lens equivalent refractive index. Lens curvatures have been measured using phakometry, Scheimpflug imaging and more recently Optical Coherence Tomography (OCT). The purpose of the present study was to compare lens power calculated using 1) a modified version of the Bennett method and 2) the lens shape obtained from extended depth OCT images.

Methods : Images of the left eye of 8 subjects (25.0 ± 4.2 y/o, spherical equivalent: -5.62 to -0.13 D) focused at distance were obtained using a custom-built extended depth OCT imaging system (Ruggeri et al, Biomed Opt Express, 2012). The images were automatically segmented and corrected for distortions due to refraction to determine the boundaries of the cornea, lens, and retina and calculate central corneal thickness, anterior chamber depth, lens thickness, vitreous chamber depth, and anterior and posterior corneal and lens curvature. For each subject, distortion correction was performed for a range of equivalent refractive indices to find the value of the refractive index, minimizing the error between predicted refraction and measured refraction. Lens power was calculated using two different methods. Method 1 is a modified version of the Bennett method which relies on corneal shape, ocular distances and refraction to predict the lens power (Hernandez et al, Biomed Opt Express, 2015). Method 2 applies the formula for the power of a thick lens using lens curvatures, thickness and equivalent refractive index. The two methods were compared using a Bland-Altman analysis.

Results : The lens power was 24.38 ± 2.02 D for the modified Bennett method (method 1) and 24.41 ± 2.16 D for the curvature-based method (method 2). The mean difference between the two methods was -0.02D, with a 95% confidence interval of ± 3.20 D. The absolute value of the error for the 8 lenses ranged from 0.10 to 2.87 D.

Conclusions : On average, there is no statistically-significant difference between curvature- and biometry-based methods for estimating lens power. However, there are significant intra-individual differences in estimated lens power between the two methods.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

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