Eye Muscle Surgery for Acquired Forms of Nystagmus

We report 3 patients with acquired nystagmus who were treated with eye muscle tenotomy and reat­ tachment. The first patient had acquired pendular nystagmus (APN) associated with multiple sclerosis (MS) and underwent bilateral medial rectus tenoto­ mies and bilateral lateral rectus recessions to cor­ rect exotropia. Eye movements were recorded before surgery, after surgery, and after surgery and treatment with memantine. Following surgery, APN decreased by'" 50% and the eXpanded Nystagmus Acuity Function (NAFX) increased by 34%. Meas­ ured Snellen acuity increased 100%, from 0.125 aD and as to 0.25. Saccades were unaffected. After treatment with memantine, APN was damped further by 69%, and NAFX was improved an addi­ tional 9%; Snellen acuity increased 60% to 0.4. The second patient had monocular APN associated with MS. The horizontal recti were tenotomized and reattached in only the eye with nystagmus. This resulted in damping of the nystagmus by 66%, and Snellen acuity increased 100% from 0.2 to 0.4. The third patient had downbeat nystagmus of undetermined etiology and preferred a chin-down (up-gaze) head position to diminish symptoms. Asymmetrical superior rectus recessions, to address head position and hypertropia, were combined with tenotomy and reattachment of both inferior recti. Surgery resulted in reduction of vertical nys­ tagmus by 46%, improvement of NAFX values by 17%, and improvement in visual acuity from 20/25 to 20/20. These preliminary results support the view that eye muscle tenotomy may diminish acquired forms of nystagmus and improve vision in selected patients. Although eye muscle surgery is established as a treat­ ment modality for congenital forms of nystagmus, its place in the therapy of acquired forms of nystagmus is debated. Currently, there is a dearth of studies that evalu­ ate the results of such surgery using reliable methods for measuring eye movements. In this chapter, we report our experience in studying the effects of surgery on the eye muscles of 3 patients with acquired forms of nystagmus. We have used a procedure developed for the treatment of congenital forms of nystagmus--eye muscle tenotomy and reattachment (T &R).1 Partial descriptions of theses cases have been previously published.2•3