Experimental Denervation of Ocular Muscles: A Critique of the Concept of Ocular Myopathy

PROGRESSIVE external ophthalmoplegia (PEO) is a slowly advancing, often hereditary disorder in which increasing weakness of the extraocular muscles (EOMs) often results in severe ptosis of the eyelids and paresis of ocular movements. This condition is of interest not only because of its fairly frequent occurrence among the neuromuscular disorders, and its interesting association with degenerations within the nervous system and elsewhere, but also because it was once considered to be a neurogenic paralysis ("progressive nuclear ophthalmoplegia" 1-4 ), and is now accepted as a primary disorder of muscle ("ocular myopathy"; the Kiloh-Nevin syndrome 5-16 ). The major bases for its acceptance as a myopathic disorder have been the occurrence of "myopathic" changes seen on histologic examination of ocular muscles obtained at biopsy or autopsy, and the occasional occurrence of similar histologic changes in muscles of the limb girdles, along with proximal weakness. Additional, less direct evidence has included the mildness or