ABSTRACT
We investigated the phenotype of CPEO, to assess whether an eso/exo deviation predominates, the prevalence of diplopia/suppression and the degree of symmetry of ophthalmoplegia. The study involved 24 patients with CPEO, with mitochondrial cytopathy confirmed by muscle biopsy. Uniocular fields of fixation measured the excursion of individual extra-ocular muscles, in the main field of muscle action. Individual muscle scores were compared in each eye, to ascertain symmetry of muscle movement. 22(92%) patients were found to have an exo deviation, with 27% of those having an associated vertical deviation. Of the 24 patients, 12 patients were binocular and 12 patients were manifest and of those, 50% had diplopia and 50% had suppression. A trend towards symmetry of ophthalmoplegia existed where 69% of all paired muscle values were within 0-5°difference.
