Visual Field–Dependent Motor Modes The: Saccades, Pursuit, Vergence, and the Geometry of Action

This paper presents a novel geometric framework, the Visual-Origin Theory of Neural Decussation, which unifies saccades, smooth pursuit, and vergence as expressions of a single, field-aligned motor architecture driven by retinal input geometry (Mohamedsalih, 2025). The theory posits that visual-motor behavior is governed by the spatial logic of light, where the optic chiasm ensures field fidelity by routing nasal (crossed) and temporal (uncrossed) retinal inputs to the contralateral hemisphere. Vergence acts as a binary modulator: convergence enhances temporal retina-driven pursuit for field preservation, while divergence triggers nasal retina-driven saccades for field reorientation.The framework resolves the pursuit–saccade laterality paradox by distinguishing sensory (contralateral V1) and motor (ipsilateral FEF for pursuit, contralateral FEF for saccades) roles, emphasizing field-aligned control over anatomical labels. The Cyclopeon Model, a monocular thought experiment, demonstrates that decussation is a geometric necessity for aligning sensory and motor systems, independent of binocularity. Testable predictions include correlations between pupil size (miosis for pursuit, mydriasis for saccades), vergence state, and motor performance, with clinical implications for vergence dysfunction, nystagmus, and conditions like convergence insufficiency or Horner syndrome.By reframing the optic chiasm as a geometry-solver and vergence as a cortical switch, this work challenges traditional reflex-based models and offers a design-oriented perspective for neuroscience, clinical diagnostics, and neurotechnology. Experimental validation can leverage eye-tracking, pupillometry, and hemispheric dissociation to test field-coherent motor control. Author:Dr. Ghassan Ahmed Mubasher MohamedsalihNeuro-OphthalmologistHamad Medical CorporationDoha, QatarORCID: https://orcid.org/0009-0000-7926-3150Email: [email protected]