SUBJECTIVE AND OBJECTIVE CYCLOROTATORY CH ANGES FOLLOWING A MODIFIED HARADA-ITO PROCEDURE FOR ACQUIRED UNI-LATERAL AND BILATERAL TROCHLEAR PALSY

Background After recently published own investigations on subjective a nd objective cyclorotatory changes following inferior oblique recessio n for inferior oblique overaction, it was our aim to determine and to compare subjective and objective cyclorotatory changes following a mod ified 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 assess ed by Harms' tangent scale. Objective cycloposition was measured by me ans of fundus cyclometry using an infrared Scanning Laser Ophthalmosco pe. Results The immediate postoperative incyclorotatory effect was 12 degrees in the unilateral group and 18 degrees in the bilateral group. Subjective and objective changes were nearly equal in both groups, wi th a subjective over-effect of 1 degrees. 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 effe ct was subjectively and objectively nearly equal in the unilateral gro up which showed a relaps of subjective excyclodeviation of 5 degrees; in the bilateral group, the subjective effect was more pronounced than the objective effect, the immediate postoperative over-effect being d isappeared. 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 lon g term regression was confirmed which objectively exceeded the amount of over-correction. As the underlying cause mechanical and sensory mec hanisms are discussed.