Perhaps the most commonly employed test of binocular muscle balance involves transferring an occluder from one eye to its fellow and then either noting the resulting movement of the eyes or asking the patient to report on the direction of the "jump." We do not know what the nature of the movement of the covered eye is in the first few seconds after it is covered. Yet it is just this movement which determines the result of the test. The purpose of this paper is to present and discuss the results of an investigation of the temporal course of this very simple type of eye movement, the relaxation of a horizontal duction.*The statement that the relaxation of a duction constitutes a simple type of eye movement requires a comparison with other types of eye movement which are uncomplicated by accommodation or pupillary contraction.
Saccadic movements of the eye
LUDVIGH E, McKINNON P, ZAITZEFF L. Temporal Course of the Relaxation of Binocular Duction (Fusion) Movements. Arch Ophthalmol. 1964;71(3):389-399. doi:10.1001/archopht.1964.00970010405018