Ocular Motility Findings in Chronic Progressive External Ophthalmoplegia

Abstract

Abstract: : Purpose:To define the phenotype of chronic progressive external ophthalmoplegia (CPEO) in cases with muscle biopsy and molecular genetic confirmation. Methods:We prospectively recruited 25 patients with CPEO defined by cytochrome c oxidase (COX) deficient fibres in muscle biopsies from vastus lateralis and the presence of single deletion, multiple deletions or point mutations of mitochondrial DNA. All patients underwent full orthoptic examination and quantitative fields of uniocular fixation using the Goldmann perimeter. Results: 23 patients (92%) had an exo deviation, 6 of whom had an associated vertical deviation. Of the 13 patients with a manifest deviation 7 had diplopia and six had supression. Of all paired extraocular muscles 68% had symmetry of movement within 5 degrees of each other. The ophthalmoplegia scores derived from the fields of uniocular fixation correlate with the percentage of COX negative fibres in vastus lateralis muscle. Conclusions: Nearly all patients with CPEO have an exo deviation. The presence of an eso deviation should prompt re evaluation of the diagnosis. Relative sparing of downgaze was observed. Diplopia is a common finding in CPEO affecting 28% of patients. The degree of ophthalmoplegia was proportional to the percentage of COX deficient fibres in vastus lateralis.

Keywords: mitochondria • strabismus • binocular vision/stereopsis