Saccades with limited downward gaze.

Fourteen patients with monocular limitation of downward gaze had vertical saccadic velocity measurements. Patients with orbital floor fracture and endocrine ophthalmopathy were excluded from the group. In four cases (29%), the difference between upward downward saccadic velocities was 20% or less. These patients were not thought to have any evidence of inferior rectus muscle paresis. In ten cases (71%), the difference between upward and downward saccades varied between 46% to 275% (average, 115%), upward saccades being more rapid in each case. These cases were all believed to have moderate to great inferior rectus muscle palsy. In one subject with a lidocaine hydrochloride-induced inferior rectus muscle palsy, upward saccades were 135% faster than downward saccades. These findings were compared with those in patients with monocular limitation of elevation, and the surgical management was reviewed.