Hypothetical Explanations for Fusion Maldevelopment Nystagmus Syndrome and Infantile Nystagmus Syndrome using a Behavioral Ocular Motor System Model

摘要

For best possible vision, the ocular motor system (OMS) continually has to keep the eyes properly aimed and stable, despite challenges to this stability, whether external or internally generated, such as in the case of nystagmus. We have developed a behavioral model of the OMS that can simulate both normal operation as well as two forms of congenitally present nystagmus, without the need for additional mechanisms to compensate for the nystagmus. The model is capable of performing saccadic and smooth pursuit tracking accurately by keeping track of commands issued to move the eyes as well as resulting position and velocity errors and the internal state of key subsystems. This information is used to calculate the necessary commands to correct errors, and perhaps more importantly, to decide when not to respond to target motion across the retina, such as during the particular portions of the uncontrolled nystagmus waveform. The resulting output of the model accurately reproduces the responses of the human OMS, and generates complex-appearing pendular nystagmus waveforms bases on the interaction of a simple set of rules.