Clinical characteristics and treatment of isolated inferior rectus paralysis. Isolated inferior rectus paralysis without mechanical restriction of the globe has received only scant attention in the literature. The authors report on 21 patients treated during the past 16 years. The etiology was congenital, traumatic, myasthenic, and vascular. Anomalous head posture, diplopia, or a disfiguring hypertropia were presenting symptoms. Diagnosis was made on the basis of the prism and cover test in the diagnostic positions and on examination of ductions and versions. The direction of the head tilt, the Bielschowsky head tilt test, and tests for cyclotropia are only of secondary diagnostic value since they may give paradoxical results. Surgery consisted of resection of the paralyzed muscle, combined with or without recession of its antagonist and/or recession of the contralateral superior oblique. After a mean follow-up of 17 months, 14 patients were cured, 6 had improved, and 1 remained unchanged. 