June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Analysis of the mechanical response of in vivo human accommodation from dynamic OCT recording
Author Affiliations & Notes
  • Arthur Ho
    Brien Holden Vision Institute, UNSW Sydney, New South Wales, Australia
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Florida, United States
  • Rong Zhu
    School of Mechanical and Manufacturing Engineering, University of New South Wales, UNSW Sydney, New South Wales, Australia
  • Pwint Phoo Wai
    School of Mechanical and Manufacturing Engineering, University of New South Wales, UNSW Sydney, New South Wales, Australia
  • Marco Ruggeri
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Florida, United States
  • Sangarapillai Kanapathipillai
    School of Mechanical and Manufacturing Engineering, University of New South Wales, UNSW Sydney, New South Wales, Australia
  • Fabrice Manns
    Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Florida, United States
    Department of Biomedical Engineering, University of Miami College of Engineering, Miami, Florida, United States
  • Footnotes
    Commercial Relationships   Arthur Ho, None; Rong Zhu, None; Pwint Phoo Wai, None; Marco Ruggeri, US Patent 8,425,037 (P); Sangarapillai Kanapathipillai, None; Fabrice Manns, US Patent 8,425,037 (P)
  • Footnotes
    Support  National Eye Institute Grants 2R01EY14225, 1R01EY021834, P30EY14801 (Center Grant); Florida Lions Eye Bank; Drs KR Olsen and ME Hildebrandt, Drs R Urs and A Furtado; an unrestricted grant from Research to Prevent Blindness; and the Australian Federal Government Cooperative Research Centre Scheme through the Vision Cooperative Research Centre.
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 325. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to Subscribers Only
      Sign In or Create an Account ×
    • Get Citation

      Arthur Ho, Rong Zhu, Pwint Phoo Wai, Marco Ruggeri, Sangarapillai Kanapathipillai, Fabrice Manns; Analysis of the mechanical response of in vivo human accommodation from dynamic OCT recording. Invest. Ophthalmol. Vis. Sci. 2017;58(8):325.

      Download citation file:


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

      ×
  • Supplements
Abstract

Purpose : Advancements in anterior eye OCT imaging has opened the opportunity to analyse in greater precision the mechanical response of the accommodation system. We applied an existing mechanical model to analyse in vivo human accommodation using images captured with a synchronous OCT system.

Methods : The study was approved by the IRB of the University of Miami and followed the tenets of the Declaration of Helsinki. Three subjects (age 22, 39 and 45 yo) were enrolled. The anterior eye of each subject was imaged at 13 fps with an OCT during accommodation tasks. Full details of the synchronous OCT imaging system have been described in Ruggeri et al (2016). Test eyes were corrected for their spherical equivalent refractive error. Following stabilisation at zero object vergence for at least 1.5 s, accommodation was initiated monocularly (left eye) by a step change to near object vergence. The younger subjects were recorded for 2 D and 4 D response. The 45 yo was tested only on 2 D vergence. Dynamic recording of the accommodation response then continued for approximately 4.5 s. Image frames were digitally analyzed to extract the geometry and positions of the lens and ciliary body. These data were fitted to the model of Beers et al (1994 & 1996) using ordinary least squares technique to obtain values for lens initial thickness (X), thickness change (A), time-constant for response (τ) and initial time of response (t0).

Results : Figure 1 shows the result for the 2 yo during 2 D accommodation. Results for X, A, τ, t0 and RMS of residuals of model fitting for both subjects and object vergences are given in Table 1. Analysis of the method using Monte Carlo techniques (1000 trials per scenario; Gaussian noise matching the fitted RMS) estimated precisions of ±0.001 (0.03%), ±0.0016 (1%), ±0.02 (6%) and ±0.013 (0.7%) for X, A, τ and t0 respectively. Thus the results are in agreement with those of Beers et al (1994 & 1996). Examination of residual errors revealed the rapid rise portion of A around t0 departs noticeably from the single exponential model. This suggests the need for either a higher-order dynamic component or additional viscous components to be added to achieve a mechanical model with greater fidelity.

Conclusions : Data from dynamic OCT recording on in vivo human accommodation were fitted to a mechanical model. Examination of residual errors suggest the need for an enhanced model with additional components.

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

 

 

×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×