June 2015
Volume 56, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2015
Combined Laser Ray Tracing and Optical Coherence Tomography system to measure changes in lens shape and on-axis and off-axis focal length with accommodation
Author Affiliations & Notes
  • Bianca Maceo Heilman
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, Miami, FL
    Biomedical Optics and Laser Laboratory, Department of Biomedical Engineering, College of Engineering, University of Miami, Coral Gables, FL
  • Marco Ruggeri
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, Miami, FL
  • Alex Gonzalez
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, Miami, FL
  • Cornelis J Rowaan
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, Miami, FL
  • Andres Bernal
    Bioniko Consulting LLC, Sunny Isles Beach, FL
  • Esdras Arrieta
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, Miami, FL
  • Arthur Ho
    Brien Holden Vision Institute, Sydney, NSW, Australia
  • Fabrice Manns
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, Miami, FL
    Biomedical Optics and Laser Laboratory, Department of Biomedical Engineering, College of Engineering, University of Miami, Coral Gables, FL
  • Jean-Marie A Parel
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, Miami, FL
    Vision Cooperative Research Centre, Brien Holden Vision Institute, University of New South Wales, Sydney, NSW, Australia
  • Footnotes
    Commercial Relationships Bianca Maceo Heilman, None; Marco Ruggeri, None; Alex Gonzalez, None; Cornelis Rowaan, None; Andres Bernal, Bioniko Consulting LLC (E); Esdras Arrieta, None; Arthur Ho, None; Fabrice Manns, None; Jean-Marie Parel, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2015, Vol.56, 1075. doi:
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      Bianca Maceo Heilman, Marco Ruggeri, Alex Gonzalez, Cornelis J Rowaan, Andres Bernal, Esdras Arrieta, Arthur Ho, Fabrice Manns, Jean-Marie A Parel; Combined Laser Ray Tracing and Optical Coherence Tomography system to measure changes in lens shape and on-axis and off-axis focal length with accommodation . Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1075.

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

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Abstract
 
Purpose
 

To measure the changes in lens shape, focal length and aberrations in ex vivo primate lenses on and off-axis during simulated accommodation.

 
Methods
 

Instrumentation: A combined LRT-OCT system was designed and built using a commercial Spectral-Domain OCT system with 16mm depth range and 8µm axial resolution in air (Bioptigen ENVISU R4400). The LRT uses the OCT scanning beam delivery system to deliver input rays to the lens. The beam delivery optics are mounted on a motorized rotation stage that pivots around the lens to allow acquisition of off-axis spot patterns. An imaging sensor was mounted on a two-dimensional (horizontal and vertical) motorized positioning stage below the lens to record the spot positions along each individual ray both on-axis and off-axis. Spot positions are used to reconstruct the ray path and calculate lens power and aberrations. The tissue is mounted in a manual lens stretcher (Bioniko LLC) that we motorized to measure the lens in the unaccommodated and accommodated states. The entire system is controlled via LabView software to allow automated data acquisition.<br /> Measurements: LRT-OCT experiments were performed on 2 cynomolgus monkey lenses from 1 donor (4 years, PMT= 2, 26 hrs) in the unstretched and stretched state. The LRT delivered 51 equally-spaced parallel meridional rays over a 6-mm diameter zone. Experiments were performed at incidence angles from -20° to +20° in 5° increments. Spot positions were recorded at 12 vertical heights along the optical axis. The on and off-axis focal length was calculated from the ray slopes.

 
Results
 

The system can acquire OCT images of the entire lens and focal length measurements at each angle. The on-axis focal length is (OD, OS): 30.2mm, 29.4mm in the unstretched state and 35.5mm, 29.6mm in the stretched state, corresponding to a power of 37.6D, 45.1D, and 44.2D, 45.4D, respectively. The off-axis focal lengths are shown in Figure 2.

 
Conclusions
 

The system is able to measure the off-axis ray-trace of the crystalline lens. The focal length of cynomolgus monkey lenses was found to decrease with increasing incidence angle.  

 
(Left) Combined LRT-OCT system. The lens stretcher and tissue cell not shown. (Right) Lens stretcher, tissue cell and control unit.
 
(Left) Combined LRT-OCT system. The lens stretcher and tissue cell not shown. (Right) Lens stretcher, tissue cell and control unit.
 
 
Change in lens focal length versus incidence angle for (Left) OD and (Right) OS in the unstretched and stretched states.
 
Change in lens focal length versus incidence angle for (Left) OD and (Right) OS in the unstretched and stretched states.

 
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