Schachar suggests that during accommodation, ciliary muscle contraction leads to a selective increase in equatorial zonular tension €”rather than to the uniform decrease (anterior, equatorial, and posterior) proposed by the Helmholtz theory €”with a subsequent pulling of the equatorial lens outward toward the sclera. Schachar postulates that accommodation occurs through the direct effect of zonular tension (as opposed to the passive effect proposed by Helmholtz), causing an increase in lens curvature.