Treatment of Knapp Class V superior oblique palsy with contralateral inferior rectus muscle recession

Objective: To describe the clinical features of patients with Knapp Class V superior oblique palsy (hypertropia greatest across the lower fields of gaze) and to present the results of a contralateral, adjustable, inferior rectus muscle recession procedure performed on these patients. Design: Clinical, cohort study. Participants: We retrospectively reviewed a series of 4 cases of superior oblique palsy (Knapp Class V). The patients, seen between the years 1991 and 2000, were selected from the private practice of I of the authors (Michael Flanders). Methods: Clinical and surgical data were extracted from the patients' records. All patients had had complete ophthalmologic and orthoptic assessments. Those included in this series had difficulty reading and compensated by lowering their chins. They had a hypertropia, which increased in downgaze, decreased in upgaze, and increased on ipsilateral head tilt. Both the ipsilateral superior oblique and inferior rectus muscles were underactive. All 4 patients underwent contralateral, adjustable, inferior rectus muscle recession. Results: The mean vertical deviation of the paretic eye preoperatively was 8.25 prism D (PD) in primary position and 20 PD in downgaze. Postoperatively it was 2 PD in primary position and 5 PD in downgaze. All patients had improved head posture and a more comfortable reading position after surgery. Mean follow-up was 6.4 years (range 1-9 years). Conclusions: Contralateral inferior rectus muscle recession is an effective treatment for visual symptoms associated with Knapp Class V superior oblique palsy.