Änderungen der subjektiven Zyklodeviation und der objektiven Zykloposition nach modifizierter Harada-Ito-Operation bei erworbener Trochlearisparese

Background After recently published own investigations on subjective and objective cyclorotatory changes following inferior oblique recession for inferior oblique overaction, it was our aim to determine and to compare subjective and objective cyclorotatory changes following a modified Harada-Ito procedure for acquired trochlear palsy. Patients and Methods Eight patients suffering from acquired uni- (n = 3) or bilateral (n = 5) trochlear palsy were investigated before surgery and 1 day, 3 days and 4 months after surgery. Subjective cyclodeviation was assessed by Harms' tangent scale. Objective cycloposition was measured by means of fundus cyclometry using an infrared Scanning Laser Ophthalmoscope. Results The immediate postoperative incyclorotatory effect was 12° in the unilateral group and 18° in the bilateral group. Subjective and objective changes were nearly equal in both groups, with a subjective over-effect of 1°. After two days of binocular stimulation a marked regression of the surgical effect was found which still increased after four months. The long term incyclorotatory effect was subjectively and objectively nearly equal in the unilateral group which showed a relaps of subjective excyclodeviation of 5°; in the bilateral group, the subjective effect was more pronounced than the objective effect, the immediate postoperative over-effect being disappeared. Conclusions In contrast to our results concerning inferior oblique muscle recession for strabismus sursoadductorius, subjective and objective cyclorotatory changes did not differ grossly following a modified Harada-Ito procedure. Subjective and objective short and long term regression was confirmed which objectively exceeded the amount of over-correction. As the underlying cause mechanical and sensory mechanisms are discussed.