Effects of visual factors on balance function in young adults
Zhong Jiamin, Huang Zhaoxin, Li Longxue, Qu Tongtong, Liu Zhuang, Fu Yifeng, Xiao Xiaofei
School of Rehabilitation Medicine of Binzhou Medical University, Yantai 264003, Shandong Province, China
Abstract: BACKGROUND: Vision is the primary sensory system to maintain balance. Approximately 50% of visually impaired youth have an increased risk of falling. Chinese reports focus more on the epidemiological survey of the number of people with visual impairment, but ignore balance performance and control strategies in such people, especially the study of influencing factors.
OBJECTIVE: To explore the effects of visual factors (degree of visual impairment: blind, partially sighted and normal vision group; vision condition: eyes open and eyes closed conditions) on balance function of young adults.
METHODS: Forty-three young adults were recruited and divided into three groups: blind (n=12), partially sighted (n=9) and normal vision group (n=22), and then underwent the following tests: one-leg stance test (eyes open and eyes closed conditions) and functional reach test (normal vision group: eyes open and closed conditions; partially sighted or blind groups: daily state). Measurement parameters between groups were analyzed using one-way analysis of variance. Paired sample t-tests were used to compare differences between different vision conditions within groups.
RESULTS AND CONCLUSION: In the one-leg stance test, the center of pressure trajectory length in the normal vision group with eyes open was significantly shorter than that in the blind and partially sighted groups (P < 0.05), and there was no significant difference between the groups when the eyes were closed (P > 0.05). Degree of injury and visual status had no significant effect on the static balance of visually impaired youth (P > 0.05). In the functional reach test, the reaching distance with eyes open was significantly greater than that with eyes closed in the normal vision group (P < 0.05) and the distance with eyes closed was significantly less than that of the blind group (P < 0.05). To conclude, visual impairment dramatically reduces the static balance of young adults, and vision conditions remarkably affect postural stability of the sighted youth, while the degree of visual impairment has no significant effect on static and dynamic balance of visually impaired youth. The lack of visual feedback can be compensated by non-visual factors in visually impaired youth.
Key words: visual impairment, balance, one-leg stance, functional reach, center of pressure