[Surgical and botulinum toxin treatment in two cases of abnormal retinal correspondence-exotropia with congenital homonymous hemianopsia].

ABSTRACT

We report 2 unusual cases of congenital occipital hemianopsia associated with abnormal retinal correspondence (ARC)-exotropia. Two Japanese males, 25 and 28 years of age, visited our hospital for surgical correction of manifest exotropia with dissociated vertical deviation and overaction of the superior oblique muscle. Visual field examination demonstrated homonymous hemianopsia with approximately 5 to 10 degrees of macular sparing. Visually evoked potential examination showed small amplitude similar to dissociated vertical deviation patients in all half-field stimulation. Electrooculogram examination demonstrated defective pursuit to the ipsilateral side. Some investigators have speculated that progressive exotropia compensates for homonymous hemianopsia and is a rare contraindication for strabismus surgery. To confirm the deterioration of motor and visual functions before surgery in these patients, we tried injections of botulinum A type toxin into the lateral rectus muscle ipsilateral to the hemianopsia. Contrary to the hypothesis, our patients had no change in their binocular visual fields and visual function. Finally, we performed recession of the lateral rectus muscle, so that both patients were satisfied with their ocular alignment, with no marked change of visual behavior.