Impact of visual impairment on balance and visual processing functions in students with special educational needs

Introduction Vision is a critical factor for children’s development. However, prevalence of visual impairment (VI) is high in students with special educational needs (SEN). Other than vision disability, this group of students is prone to having functional deficits. It is unclear whether visual problems relate to these compromised functional deficits. This study aimed to assess the impact of vision on visual processing functions and balance performance in SEN students through a community service in special schools. Methods A total of 104 (chronological age 14.3 ± 4.3 years, 43 females) SEN students in Taiwan were assessed and classified as having normal vision (NV) or vision impairment (VI). Visual acuity (distance and near) and contrast sensitivity (CS) were measured as the visual outcomes. Visual processing function assessment included facial expression recognition by Heidi expression test, in terms of card matching (FEC), and examiner’s facial expression matching (FEE), and visual orientation recognition (by mailbox game, VO). Dynamic balance was assessed with Timed Up and Go (TUG) test, while static standing balance was assessed using a force plate to measure the postural sway in double-legged feet-together and tandem stance with eyes open and closed conditions. Static balance was presented in terms of the change in the centre of pressure in maximal medial-lateral (ML) and antero-posterior (AP) sways, sway variability (V), and sway path length (L). Results Although visual acuity was significantly worse in VI than NV (p < 0.001), CS was similar in the two groups (p = 0.08). VO, FEC, and FEE also did not differ significantly between groups (p > 0.05). NV performed better in the TUG than VI (p = 0.03). There was a significant interaction between eye condition and the vision group (p < 0.05) for static balance. Pairwise comparisons showed that NV swayed significantly less in ML than VI under tandem stance-open eye condition (p = 0.04), but significantly more in closed eye condition (p = 0.03). Conversely, VI had less V and shorter L than NV under tandem stance-closed eye condition (p = 0.03). Conclusion This study is the first to our knowledge to examine the effect of vision on visual processing functions and balance performance in SEN students. Vision did not appear to be the major reason for impairment in visual processing. However, vision plays an important role in maintaining dynamic and static balance in SEN students. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was supported by The Hong Kong Polytechnic University Community Service Fund (83CT) and Chinese Mainland Affairs Office Fund. We thank the financial support from Lions Clubs International MD300 Taiwan Eye Care Network Committee, Taiwan. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Hong Kong Polytechnic University Human Subjects Ethics Subcommittee All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes The data can be provided upon request.