視標追跡眼運動と半規管眼運動の相互作用について

Abstract

Impaired smooth pursuit eye movements may be corrected by saccades to repair visual errors during an eye tracking test (ETT).However, in this study, most of the cases that showed a saccadic pattern during ETT demonstrated smooth eye movements in a pendular rotation test (PRT) with the eyes open and fixed at the stand still target in lightness due to interaction between the visuoocular and vestibuloocular systems. The incidence and character of the two kinds of induced eye movements in horizontal ETT and PRT with the eyes open were investigated.Investigated were thirty one cases among out-patients in the Neuro-Otological Clinic of Kitasato University Hospital in 1996. All cases showed saccadic patterns in ETT, fulfilling the following criteria: each half period to the right and left containing three or more saccades with a maximum amplitude of four or more degrees. Only 3 cases or 10% of the 31 patients showed saccadic pattern in PRT with the eyes open.The saccadic index (S.I.) (maximum amplitude multiplied by the number of saccades) was calculated in each case. The combined SI of both directions was between 75.8 to 100.6 in the 3 cases who had saccadic pattern in PRT with the eyes open. VOR gains remained in the low range (0.40 to 0.57). However, cases who showed high S.I. in ETT, but had smooth pursuit eye movement in PRT with the eyes open showed a high VOR gain. We concluded that most cases of saccadic pattern in ETT showed smooth eye movements in PRT with the eyes open and fixed at the target due to a high VOR gain, but in 10% of cases no increase was recorded due to a failure of vestibular compensation.