INVESTIGATIONS ON SUBJECTIVE AND OBJECTIVE CYCLOROTATORY CHANGES AFTER INFERIOR OBLIQUE MUSCLE RECESSION

Purpose. To determine subjective and objective cyclorotatory changes a fter surgery for oblique muscle disorders and to analyze the mechanism s of the well-known, long-term, postoperative, subjective cyclotorsion al changes. Methods. Twenty-six patients underwent unilateral inferior oblique muscle recession for strabismus sursoadductorius (inferior ob lique overfunction). Subjective and objective cyclodeviation were exam ined before surgery with and without diagnostic occlusion, as well as I day, 3 days, and 4 months after surgery. Subjective cyclodeviation w as assessed by Harms' tangent scale. Objective cycloposition was measu red by means of fundus cyclometry, a novel method using an infrared sc anning laser ophthalmoscope. Results. Diagnostic occlusion did not lea d to significant changes in either objective or subjective cyclodeviat ion. Preoperative objective excycloposition was nearly equally distrib uted between affected eyes and fellow eyes. Early surgically induced i ncyclorotatory effects were more pronounced objectively than subjectiv ely. On long-term follow-up, a reduction in the incyclorotatory effect was found to be smaller subjectively than objectively. A significant difference between subjective and objective cycloposition was seen ear ly after surgery, and a significant difference between subjective and objective cyclorotatory change was found immediately after surgery and on long-term follow-up. Conclusions. Long-term regression of the incy clorotatory effect after inferior oblique muscle recession was confirm ed objectively and subjectively and can be explained as a cessation of preoperatively required binocular compensatory innervation. The autho rs conclude that the difference between objective and subjective regre ssion is caused by sensory cyclofusion.