DOI: 10.5061/dryad.0gb5mkm9b
title: Postural stability and optic flow sensitivity following sight restoration from congenital bilateral cataracts

description: 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.
description: In Experiment 1, cataract-treated participants and sighted
 controls stood on a foam pad placed on a Nintendo Wii Balance Board. Their
 static balance was recorded under two conditions: with eyes open and
 closed. In the closed eyes condition, participants were blindfolded to
 ensure that even if they briefly opened their eyes, they would still be
 unable to see anything. The order of the two conditions was
 counterbalanced across participants, with each condition lasting 40 s.
 Data was recorded with a sampling rate of 30 Hz. Body sway was assessed by
 determining the area of the 95% confidence ellipse for each participant
 and condition. In Experiment 2, we tested static
 balance in a group of cataract-treated participants, a group of
 age-matched sighted controls tested in normal visual conditions, and a
 second group of age-matched sighted controls tested with visual blur.
 Participants were tested during the presentation of a static baseline
 (static), during which a static field of 300 dots was displayed for 40
 seconds. Subsequently, four conditions were presented in random order:
 expanding optic flow, contracting optic flow, translational motion (either
 left-to-right or right-to-left, counterbalanced across participants), and
 static (repeating the initial static field of dots). For conditions
 involving motion, optic flow patterns were presented for the initial 20
 seconds, followed by 20 seconds of static dots. During this static phase,
 the final frame of the optic flow phase was displayed statically for 20
 seconds. This solution allowed us to explore whether participants
 exhibited more sway during the presentation of optic flow patterns or as
 an after-effect once the motion stopped abruptly. Since there was no
 significant difference in sway between the first and second halves of each
 condition, we analyzed the entire 40 seconds together. We fitted the 95%
 confidence ellipse to the Centre of Pressure (CoP) data for each
 participant and condition. Then, we extracted the following standard
 parameters: the ellipse area, the standard deviations (SD) along the
 anteroposterior and mediolateral directions (AP-SD and ML-SD,
 respectively), and computed the ratio between the latter two.
description: # Postural stability and optic flow sensitivity following sight
 restoration from congenital bilateral cataracts
 [https://doi.org/10.5061/dryad.0gb5mkm9b](https://doi.org/10.5061/dryad.0gb5mkm9b) The file contains the full dataset for Experiments 1 and 2. Exp1.txt displays results for Experiment 1, including individual values for the area of the 95% confidence ellipse for each participant under both open and closed eyes conditions. Data is presented for both the cataract-treated group and the sighted control group. Exp2_3groups.txt displays results for Experiment 2 for the 3 groups (cataract-treated, sighted tested in normal visual conditions, and sighted tested with visual blur). It includes individual values for the area of the 95% confidence ellipse and the standard deviations (SD) along the anteroposterior (AP-SD) and mediolateral (ML-SD) directions for each participant and condition (two repetitions of the static condition, radial expanding optic flow, radial contracting optic flow, and translational motion). Exp2_development.txt displays results for the developing sighted population, including individual values for the area of the 95% confidence ellipse and the standard deviations (SD) along the anteroposterior (AP-SD) and mediolateral (ML-SD) directions for each participant and condition. Additionally, each file includes information on height (in cm) and age at testing (in years) for all participants in each group. Demographics_cataract.txt includes additional information on the cataract-treated participants, such as age at surgery, pre-surgery and post-surgery spatial visual acuity (measured by contrast sensitivity function, CSF cut-off frequency, in cycles per degree), and time since surgery (TSS) for the cataract-treated group (in years).\ ANOVAs were conducted using the software Jamovi (Version 2.3.19.0). The Linear Mixed Models for Experiment 2 were conducted with MATLAB (Version R2021a). The Matlab codes for the models and the .txt files with the raw data for the cataract-treated patients and the sighted controls are also provided.