A conceptual discussion on relationship between vergence and conjugate eye movements on the viewpoint of system and control engineering

Vergence eye movements are commonly treated as members of a distinct subclass of eye movements along with four types of conjugate movements: saccade, smooth pursuit, optokinetic response (OKR), and vestibulo-ocular reflex (VOR). According to this classification, many researchers try to determine the particular neural pathways or signal sources related to vergence, and have not been aware that most vergence eye movements are controlled using the same ocular motor system as conjugate movements. I suggest that, in fact, fusional vergence is saccade, accommodative vergence (Baker, R. et al., Ann. B. Y Acad Sci. Part IV, p.171 1981; Robinson, D.A., 1977) is smooth pursuit, flow induced vergence (Baker et al.) is OKP, and the vergence occurring by head movement is a family of VOR. I show the grounds for this suggestion.