The aim of this study was to assess the plasticity of human
voluntary fixational eye movement control in relation to visual
experience/chronic visual deprivation. Twelve blind adults
participated (self-reported vision ≤ light perception in
each eye; age range = 23–56 years; visual experience range
= 0–28 years; blindness duration range = 6–55 years).
Infrared-based recordings of horizontal eye movements were made
before, during, and immediately after three 30-s periods of
auditory ocular motor feedback, while participants were instructed
to look straight ahead and keep their eyes as steady as possible.
Percent change in horizontal displacement of the eye during
and after feedback was compared with the no-feedback baseline.
Eleven of the 12 individuals demonstrated feedback-mediated increase
in eye stability, which improved as a function of visual experience.
Improved eye stability was inversely related to duration of blindness.
Clearly, blind adults can use nonvisual external feedback to
stabilize gaze. Thus, the fixational subsystem can exhibit improved
voluntary control despite chronic visual deprivation. Possible
cortical and subcortical mechanisms are discussed.