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

Abstract

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 (age 14.3 ± 4.3 years, 43 girls) SEN students in Taiwan were assessed, who were 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 orientation recognition (mailbox game, MB) and facial expression recognition [Heidi expression test, in terms of card matching] (HC), and examiner′s facial expression matching (HF)]. 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). MB, HC, and HF 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-close 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.