STRABISMUS AND MITOCHONDRIAL DEFECTS IN CHRONIC PROGRESSIVE EXTERNAL OPHTHALMOPLEGIA

PURPOSE: To describe the results of strabismus surgery on three patien ts with chronic progressive external ophthalmoplegia, a group of rare disorders characterized by ptosis and slowly progressive ophthalmopare sis that has been shown to result from defects in mitochondrial DNA. M ETHODS: Strabismus surgery using the adjustable suture technique was p erformed in three patients with strabismus and chronic progressive ext ernal ophthalmoplegia confirmed by clinical, biochemical histopatholog ic, and genetic criteria. All three patients had mitochondrial DNA del etions. Two patients were exotropic; one patient was esotropic. RESULT S: Rectus muscle recessions were initially unsuccessful in correcting strabismus in one patient, although a subsequent procedure employing r ectus muscle resections was successful in alleviating a significant he ad turn and improved ocular alignment. In the two other patients, a si ngle procedure consisting of rectus muscle recessions combined with la rge rectus muscle resections successfully achieved good postoperative alignment. The amount of surgery performed in these three patients exc eeded that predicted in standard strabismus tables, CONCLUSIONS: The m yopathic process that results in chronic progressive external ophthalm oplegia renders rectus muscle recessions less effective compared with resections for correcting the associated strabismus seen in these pati ents. Rectus muscle resections therefore should be an integral procedu re in the surgical management of the strabismus associated with chroni c progressive external ophthalmoplegia.