Abstract
Purpose: :
To develop a method for temporarily damping nystagmus by means of mechanical restriction on one eye and investigate the effect on the fellow eye in patients with INS.
Methods: :
Subjects with infantile nystagmus syndrome participated in the study. Mechanical restriction was accomplished by fitting an eye coil (Skalar) attached to a handle that could be gently held on the eye without disturbing vision. Binocular eye movements were monitored and digitized using video ocular tracking technology (Eyelink1000) in two different visual conditions: 1) binocular fixation of a 0.5º dot and 2) both eyes in the dark.
Results: :
The nystagmus, both in restricted eyes and in fellow eyes, was dramatically reduced and even completely eliminated for the duration of the restriction. The amplitude, frequency, and waveform in both eyes were signficantly changed. Among the differences observed in the each of the fixation conditions, most notable was that the nystagmus in the fellow eye reduced more during binocular lighted fixation conditions than in binocular dark conditions.
Conclusions: :
Mechanical restriction of one eye in INS patients significantly reduced the amplitude and frequency of binocular eye movements. This method may prove useful when a temporal cessation of nystagmus is needed and may suggest new nystagmus therapies. The effects on fellow eye in dark conditions suggests a further role of propriorceptive signals in defining the characteristics of INS.
Keywords: nystagmus • ocular motor control • eye movements