Introduction Vision is critical for children’s development. However, prevalence of visual impairment (VI) is high in students with special educational needs (SEN). Other than VI, SEN students are prone to having functional deficits. Whether visual problems relate to these functional deficits is unclear. This study aimed to assess the impact of vision on visual processing functions and balance in SEN students through a community service. Methods Visual acuity (VA) and contrast sensitivity were measured in a total of 104 (aged 14.3±4.3) SEN students as the visual outcomes, followed by retinoscopy. Visual processing function assessment included facial expression recognition by card matching examiner’s facial expression matching, and visual orientation recognition. Dynamic balance, by Timed Up and Go test, and static standing balance (postural sway in double-legged standing with feet-together and tandem-stance for open-eye and closed-eye conditions) were assessed. Static balance was presented in terms of the maximal medial-lateral and antero-posterior sways. Results Of the 104 students, 62 (59.6%) were classified as visually impaired according to WHO classification of visual impairment based on presenting distance acuity. Ocular problems (e.g. optic nerve anomaly, uncorrected/ under-corrected refractive errors) and neurological anomalies were the major causes of vision loss. VA was positively associated with visual processing functions (all p ≤ 0.01), as SEN students with better vision tended to perform better in visual orientation and facial expression recognition tasks, as well as dynamic balance function (p = 0.04). For the static balance, postural sway and VA showed a positive relationship under open-eye and tandem stance conditions. However, the relationship between postural sway and VA became negative under closed-eye and tandem stance conditions. Conclusion This study found a high prevalence of SEN students with visual impairment, in which many of them were undetected. Optometric examination is important to improve their visual function to minimize the effect of vision on functional performance. Vision is critical in visual processing as well as playing an important role in maintaining balance in SEN students.

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.