Mechanical Coupling of Extraocular Muscles, Optic Nerve Tension, and Orbital Fat as a Driver of Directional Posterior Ocular Deformation

Posterior ocular deformation is central to myopia-associated structural change, yet a unified mechanical explanation for directionally biased deformation remains lacking. We propose a biomechanical hypothesis in which extraocular muscles, optic nerve tension, and orbital fat act as a mechanically coupled system that generates directional loading on the posterior globe. In this framework, the medial rectus contributes posteriorly directed force, the superior oblique contributes a rotational component, optic nerve tension transmits and concentrates posterior traction, and orbital fat provides a viscoelastic constraint that redistributes load within the orbit. Their combined action is proposed to bias posterior ocular deformation in specific directions, thereby providing a common mechanical basis for optic disc tilt, optic disc torsion, and related posterior pole shape changes. This article develops the mechanical logic of the model, distinguishes it from scalar growth-centered accounts of myopia progression, and outlines testable predictions for imaging, gaze-dependent biomechanics, and clinical intervention. The model is intended as a hypothesis-generating framework for directional ocular biomechanics rather than as a completed experimental account.