A pulse-step model of accommodation dynamics in the aging eye.
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.
Schor
Clifton M
CM
School of Optometry, University of California at Berkeley, Vision Science Group, 512 Minor Hall, Berkeley, CA 94720-2020, USA. schor@socrates.berkely.edu
Bharadwaj
Shrikant R
SR
D000065:Accommodation, Ocular / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology*; D002924:Ciliary Body / Q000294:innervation; D004548:Elasticity; D006801:Humans; D007908:Lens, Crystalline / Q000502:physiology; D008875:Middle Aged; D008954:Models, Biological; D009130:Muscle, Smooth / Q000294:innervation; D011305:Presbyopia / Q000503:physiopathology; D014783:Viscosity