Initial tension of the human extraocular muscles in the primary eye position.

This study proposes a mathematical model to estimate the initial tension forces of the extraocular muscles (EOMs). These forces are responsible for the mechanical equilibrium of the eye suspended in primary position. The passive contributions were obtained using the corresponding Cauchy stress-stretch relationships based on the previous clinical experimental data; whereas the active contributions were obtained using an optimum method with weakening the effect of innervation. The initial tension forces of the EOMs were estimated to be 48.8±14.2mN for the lateral rectus, 89.2±31.6mN for the medial rectus, 50.6±17.6mN for the superior rectus, 46.2±13.4mN for the inferior rectus, 15.6±8.3mN for the superior oblique, and 17.1±12.1mN for the inferior oblique.