Functional anatomy of the orbit in strabismus surgery: Connective tissues, pulleys, and the modern surgical implications of the “arc of contact” paradigm
Authors: Freitas‐da‐Costa Paulo , Madeira Maria Dulce 
Published: January 2024

AbstractOculomotricity is a multidimensional domain characterised by a delicate interplay of anatomical structures and physiological processes. This manuscript meticulously dissects the nuances of this interplay, bringing to the fore the integral role of the extraocular muscles (EOMs) and their intricate relationship with the myriad orbital connective tissues as it harmoniously orchestrates binocular movements, ensuring synchronised and fluid visual tracking. Historically, the peripheral oculomotor apparatus was conceptualised as a rudimentary system predominantly driven by neural directives. While widely accepted, this perspective offered a limited view of the complexities inherent in ocular movement mechanics. The twentieth century heralded a paradigm shift in this understanding. With advances in anatomical research and imaging techniques, a much clearer picture of the gross anatomy of the EOMs emerged. This clarity challenged traditional viewpoints, suggesting that the inherent biomechanical properties of the EOMs, coupled with their associated tissue pulleys, play a pivotal role in dictating eye movement dynamics. Central to this revised understanding is the “arc of contact” paradigm. This concept delves deep into the mechanics of eye rotation, elucidating the significance of the point of contact between the EOMs and the eyeball. The arc of contact is not just a static anatomical feature; its length and orientation play a crucial role in determining the effective torque generated by a muscle, thereby influencing the amplitude and direction of eye rotation. The dynamic nature of this arc, influenced by the position and tension of the muscle pulleys, offers a more comprehensive model for understanding ocular kinematics. Previously overlooked in traditional models, muscle pulleys have now emerged as central players in the biomechanics of eye movement. These anatomical structures, formed by dense connective tissues, guide the paths of the EOMs, ensuring that their pulling angles remain optimal across a range of gaze directions. The non‐linear paths resulting from these pulleys provide a more dynamic and intricate understanding of eye movement, challenging two‐dimensional, linear models of orbital anatomy. The implications of these revelations extend beyond mere theoretical knowledge. The insights garnered from this research promise transformative potential in the realm of strabismus surgery. Recognising the pivotal role of muscle pulleys and the “arc of contact” paradigm allows for more precise surgical interventions, ensuring better post‐operative outcomes and minimising the risk of complications. Surgical procedures that previously relied on basic mechanical principles now stand to benefit from a more nuanced understanding of the underlying anatomical and physiological dynamics. In conclusion, this manuscript serves as a testament to the ever‐evolving nature of scientific knowledge. Challenging established norms and introducing fresh perspectives pave the way for more effective and informed clinical interventions in strabismus surgery.