vergences center receives vergence stimulus (VS) when fixation disparity level reaches a certain level. Tonic vErgence is added to the sum of fast fusional vergence and slow vergence adaptor. Accommodative induced vergence changes are increased by the cross links of AC/A. Proximal convergence also contributes to total vergence response. Alteration in vergence response results in immediate changes through the fusional vergence controller with a subsequent change in vergence adaptation. Accommodation has a similar negative feedback control system with an accommodative adaptor reducing the load on the accommodation control center. Similar crosslinks occur through CAC (convergence/acc-conv) crosslinks.