Postural stability and optic flow sensitivity following sight restoration from congenital bilateral cataracts

Vision is crucial for maintaining balance and facilitating locomotion.
Optic flow, for example, provides key self-motion cues for navigation.
Congenital blindness typically leads to increased postural sway and
impaired navigation. Here, we investigated postural stability and optic
flow sensitivity in individuals surgically treated for congenital dense
bilateral cataracts years after birth. Experiment 1 assessed whether
cataract-treated participants rely on vision to stabilize their stance
with eyes open compared to closed. In contrast to controls,
cataract-treated participants only marginally decreased their sway with
open eyes, indicating a reduced ability to use vision for stabilization.
Interestingly, they improved over time following surgery, suggesting
partial learning in utilizing visual input to enhance stability.
Experiment 2 assessed whether different radial and translational optic
flow patterns elicit distinct effects on body sway, which would indicate
illusory sensorimotor perceptions. We included a group of typically
sighted controls and a group of controls with experimentally reduced
visual acuity. While cataract-treated participants exhibited greater sway
than controls, their sway was less influenced by specific optic flow
patterns. Overall, the study showed that cataract-treated individuals
exhibit only partial learning in utilizing vision for stabilization after
surgery. Moreover, optic flow evokes less pronounced illusory self-motion
perception compared to typically sighted individuals.