[A new method of surgery of nystagmus blockage syndrome].

Structural surgery is based on a model in which eye movements follow the ball-joint principle, i.e., there is absolute freedom of movement in all possible directions. Nystagmus blockage or convergence excess is regarded as a surplus of the medial rectus muscle. The relation between the weight of the globe and the muscle mass is taken into account. The medial rectus muscle is weakened by splitting it into 3 parts. The central part remains in its physiologic anatomic position in order to preserve normal convergence and binocularity, while the upper and lower portions prevent divergence. Additional prior weakening is accomplished by performing a tenonectomy.