Kenneth Ciuffreda


A sensitivity analysis was performed to determine the variation in response to changes in parameter values of a previously developed nonlinear static model of accommodation and vergence. To determine normal behavior, simultation responses were obtained using previously determined parameter values for 4 subjects under two conditions. First, relative accommodation was evaluated at a constant 2.5 MA vergence stimulus, varying accommodation from -2.5 to 2.5 D in 0.25 D steps. Second, relative vergence was evaluated at a constant 2.5 D accommodative stimulus, varying vergence from 25 PD base-in to 25 PD base-out in 5 PD steps. Sensitivity of the model parameters, consisting of controller gains for accommodation (ACG) and vergence (VCG), cross-link gains for accommodation-to-vergence (AC) and vergence-to-accommodation (CA), deadspace operators for accommodation (AE +/- VD), and the tonic levels for accommodation (ABIAS) and vergence (VBIAS), were assessed by varying them at 50% and 150% of normal values. It was found that the system was most sensitive to variation in cross-link gains, moderately sensitive to controller gain and tonic values, and least sensitive to deadspace operator values. These results provide a quantitative basis for, and provide insight into, the prevalence of ocular dysfunction associated with abnormal cross-link gains, such as strabismus.


Year: 1992

Program Number: 1:00 pm

Author Affiliation: n/a

Co-Authors: George Hung

Co-Author Affiliation: n/a

Room: Scotland A