rss
Br J Ophthalmol 2006;90:1304-1309 doi:10.1136/bjo.2006.100347
  • Laboratory science - Extended reports

Insights into the age-related decline in the amplitude of accommodation of the human lens using a non-linear finite-element model

  1. R A Schachar1,
  2. A Abolmaali2,
  3. T Le2
  1. 1Department of Physics, University of Texas at Arlington, Arlington, Texas, USA
  2. 2Department of Civil and Environmental Engineering, University of Texas at Arlington, Arlington, Texas
  1. Correspondence to: R A Schachar PO Box 601149, Dallas, TX 75229, USA;ron{at}2ras.com
  • Accepted 5 July 2006
  • Published Online First 19 July 2006

Abstract

Aim: To understand the effect of the geometric and material properties of the lens on the age-related decline in accommodative amplitude.

Methods: Using a non-linear finite-element model, a parametric assessment was carried out to determine the effect of stiffness of the cortex, nucleus, capsule and zonules, and that of thickness of the capsule and lens, on the change in central optical power (COP) associated with zonular traction. Convergence was required for all solutions.

Results: Increasing either capsular stiffness or capsular thickness was associated with an increase in the change in COP for any specific amount of zonular traction. Weakening the attachment between the capsule and its underlying cortex increased the magnitude of the change in COP. When the hardness of the total lens stroma, cortex or nucleus was increased, there was a reduction in the amount of change in COP associated with a fixed amount of zonular traction.

Conclusions: Increasing lens hardness reduces accommodative amplitude; however, as hardness of the lens does not occur until after the fourth decade of life, the age-related decline in accommodative amplitude must be due to another mechanism. One explanation is a progressive decline in the magnitude of the maximum force exerted by the zonules with ageing.

Footnotes

  • Published Online First 19 July 2006

  • Competing interests: RAS has a financial interest in the surgical reversal of presbyopia.

This Article

  1. Abstract
  2. Full text
  3. PDF
  4. All versions of this article:
    1. bjo.2006.100347v1
    2. 90/10/1304 most recent

Responses

  1. Submit a response
  2. No responses published

Register for free content

The full back archive is now available for all BMJ Journals. Institutional subscribers may access the entire archive as part of their subscription. Personal subscribers will also have access to all content when logged in. Non-subscribers who register have free access to all articles published before 2006 right back to volume 1 issue 1. Register here to access the free archive of all BMJ Journals.

Don't forget to sign up for content alerts so you keep up to date with all the articles as they are published.