recession

Recession is a strabismus operation that weakens an extraocular muscle by moving its insertion farther back on the globe. Moving the insertion back slackens the muscle and decreases its pull.^1,2 The procedure can be used on any extraocular muscle.²

In a rectus muscle recession, two absorbable sutures are tied through the outer quarters of the tendon, and the tendon is detached from the sclera. The planned amount of recession is measured and marked on the sclera with calipers, and the end of the muscle is sutured to the sclera at that distance behind the original insertion.¹

Setting the insertion back shifts the point where the muscle meets the globe tangentially, so the muscle loses some of its rotational force, or torque. That loss is smaller than generally assumed; an 8-mm recession of a medial rectus reduces torque by only 1.5% in primary position and by 10% in 10° of adduction.³ The slackened muscle also generates less contractile force, and the surgery severs supporting tissues around the muscle, which adds to the weakening. Millimeter for millimeter, a recession reduces a deviation more than a resection does.³