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Vision Res. 2005 May;45(10):1237-54. Epub 2004 Dec 16.

A pulse-step model of accommodation dynamics in the aging eye.

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School of Optometry, University of California at Berkeley, Vision Science Group, 512 Minor Hall, Berkeley, CA 94720-2020, USA.


We have developed a dynamic model of accommodation that combines independent phasic-velocity and tonic-position neural signals to control position, velocity and acceleration properties of accommodative step responses. Phasic and tonic signals were obtained from neural integration of a fixed-height acceleration-pulse and variable-height velocity-step respectively to control independent acceleration and velocity properties of the step response. Duration and amplitude of the acceleration-pulse are increased with age to compensate for age-related increases of visco-elastic properties of the lens to maintain youthful velocity. The model illustrates a neural control strategy that is similar to the classical neural control model of step changes by the saccadic and vergence systems.

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