April 2011
Volume 52, Issue 14
Free
ARVO Annual Meeting Abstract  |   April 2011
Estimation of Central Average Group Refractive Index of Crystalline Lens from Optical Thickness Measurements
Author Affiliations & Notes
  • Arthur Ho
    Brien Holden Vision Institute, Sydney, Australia
    School of Optometry & Vision Science, University of New South Wales, Sydney, Australia
  • Fabrice Manns
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller's School of Medicine, Miami, Florida
    Biomedical Optics and Laser Laboratory, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida
  • Bianca Maceo
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller's School of Medicine, Miami, Florida
    Biomedical Optics and Laser Laboratory, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida
  • David Borja
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller's School of Medicine, Miami, Florida
    Biomedical Optics and Laser Laboratory, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida
  • Stephen Uhlhorn
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller's School of Medicine, Miami, Florida
  • Esdras Arrieta
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller's School of Medicine, Miami, Florida
    Biomedical Optics and Laser Laboratory, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida
  • Jean-Marie Parel
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller's School of Medicine, Miami, Florida
    Vision Cooperative Research Centre, Sydney, Australia
  • Footnotes
    Commercial Relationships  Arthur Ho, None; Fabrice Manns, None; Bianca Maceo, None; David Borja, None; Stephen Uhlhorn, None; Esdras Arrieta, None; Jean-Marie Parel, None
  • Footnotes
    Support  NIH Grant 2R01EY14225, Australian Government CRC Program (Vision CRC), NIH Center Grant P30EY14801, the Henri and Flore Lesieur Foundation (JMP), Florida Lions Eye Bank, Research to Prevent Blindness
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 815. doi:https://doi.org/
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      Arthur Ho, Fabrice Manns, Bianca Maceo, David Borja, Stephen Uhlhorn, Esdras Arrieta, Jean-Marie Parel; Estimation of Central Average Group Refractive Index of Crystalline Lens from Optical Thickness Measurements. Invest. Ophthalmol. Vis. Sci. 2011;52(14):815. doi: https://doi.org/.

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

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Abstract
 
Purpose:
 

To determine the central/axial average group refractive index (AGRI) of the crystalline lens for the purpose of converting optical thickness measurements to geometrical thickness values. The age-dependency of AGRI was also investigated.

 
Methods:
 

Isolated baboon (n=56, 1.8-28 y/o) and human lenses (n=103, 6-94 y/o) were imaged with either a custom-built time-domain OCT system (24 baboon, 53 human), or a shadow-photographic system (35 baboon, 51 human) fitted with a digital camera. From the OCT images, the central/axial optical path length (OPL) was extracted while from shadow-photographic images, the central thickness (CT) of lenses was measured. The quotient of the OPL to CT represents the AGRI of the lens along its central axis.

 
Results:
 

The average AGRI was 1.414 and 1.450 for baboon and human lenses respectively. An age-dependency of AGRI was apparent in the lens of both species. The youngest age-range of the baboon lens returned an average AGRI of 1.362 while the oldest returned AGRI of 1.488. In human lenses, the 14-29 y/o group had AGRI of 1.443 while the oldest (60-69 y/o) had AGRI of 1.479. By algebraically combining two mathematical relationships obtained by linear regression between OPL and CT with age, age-dependency was found to be AGRI=-4.770×10-5 Age2 + 4.834×10-3 Age + 1.355 for baboons and AGRI=-6.852×10-6 Age2 + 1.826×10-3 Age +1.380 for human.

 
Conclusions:
 

Unlike previous studies, we find that the average group refractive index of baboon and human lenses increases with age. This increase with age is consistent with the formation of a refractive index plateau.

 
Keywords: optical properties • image processing 
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