Dynamic stability evaluation of trunk accelerations during walking in blind and sighted individuals.

BACKGROUND: Dynamic stability is a fundamental goal in standing activities. In this regard, monitoring, analysis, and interventions made to improve stability is a research topic investigated in the biomechanics of human movements. Vision has a major role to play in controlling human movement. Nonetheless, little is known about the effects of visual deprivation, especially from birth on dynamic gait stability. METHODS: The current study was conducted on 20 congenital blind and 10 sighted people (15-38 years). To evaluate the dynamic stability, descriptive data, harmonic ratio (HR), improved harmonic ratio (iHR), and root mean square (RMS), based on trunk acceleration data were measured in three axes: anteroposterior (AP), vertical (V), and mediolateral (ML) while participants walked an eight-meter straight path. RESULTS: In the comparison of blind and sighted people (eyes open), standard deviation, HR, iHR, and RMS indices were found to be significantly different in both AP and V directions. All the mentioned parameters were significantly lower in blind than in sighted participants. In the comparison of blind people and sighted ones with closed eyes, changes were observed in the maximum, range, standard deviation, and RMS only in the AP axis. In the comparison between eyes open and closed in sighted people, a significant difference was found only in the harmonic ratio of the vertical axis. CONCLUSION: Visual deprivation led to a decrease in dynamic stability parameters in the AP and V axes. Even the movement of sighted people in unchallenged conditions is dependent on visual information.

Assessment of the effects of white cane variables on step symmetry of blind individuals.

BACKGROUND: Step symmetry is an important feature of human gait and is often regarded as a key index of healthy individuals' walking. This study evaluated the effects of height, white cane technique, and cane tip on symmetrical gait in blind individuals. MATERIALS AND METHODS: Twenty blind and ten sighted subjects, aged 15-38 years, participated in this study. The harmonic ratio (HR) and improved HR (iHR) were measured by trunk accelerometer as gait symmetry index in three axes: anteroposterior (AP), vertical, and mediolateral of the body. These parameters were measured in the sighted group in open-eye conditions and in the blind group in five experimental conditions with different two heights (standard and long), two tips (pencil and roller), and two techniques (two-point touch and constant contact) of white cane when they walked in the 6-m path. RESULTS: There was a significant difference between HR and iHR of the blind and sighted group, which indicates a significant reduction of symmetry loss in the blind group. Among the five different conditions studied in the group of blind people, an increase was observed in the HR and the iHR on the AP axis during the application of a standard cane with a roller tip, which indicated an increase in symmetry. CONCLUSION: Based on the results, a long cane with a pencil tip and a standard cane with a roller tip in the constant contact technique can increase step symmetry.

Development and validation of a white cane use perceived advantages and disadvantages (WCPAD) questionnaire.

BACKGROUND: The white cane is globally an important tool in orientation and mobility for blind and visually impaired people, but it is not often used. The goal of this study was to develop and validate the white cane use perceived advantages and disadvantages (WCPAD) questionnaire for detecting effective factors in the use or non-use of canes. METHOD: The initial questionnaire items were extracted through semi-structured interviews with 21 blind or severely impaired vision individuals under two main themes, the perceived advantages, and disadvantages of using a white cane. Linguistic validity and writing evaluation with seven experts, face validity with 23 blind persons, content validity ratio (CVR), and content validity index (CVI) were used for assessment of validity. Internal and external reliability assessment was done using Cronbach's alpha and intra-class correlation coefficient (ICC). Explanatory factor analysis was conducted to identify the factors of the questionnaire; then, corrected item-total correlations, convergent and discriminant validity, and Confirmatory Factor Analyses (CFA) were done, and model fit indices were reported. A total of 320 blind and severe visual impaired individuals (138 males and 182 females) participated in the study. The final questionnaire contained 12 questions in perceived advantages and 21 in perceived disadvantages. RESULTS: Three factors (social participation, mobility, and culture) extracted for perceived advantages which explained 67.95% of the total variance, Cronbach-α for the three extracted factors was between 0.75 and 0.91. Four factors (social, safety, ergonomics, and family) for perceived disadvantages were extracted which explained 50.98% of the total variance. Cronbach-α for the four extracted factors was from 0.75 to 0.88. CFA confirmed the final models for perceived advantages and disadvantages. CONCLUSION: WCPAD questionnaire has good reliability and validity, and the factors obtained from factor analysis can measure the reasons for using or otherwise of white canes.

Subjective and objective survey of office lighting: effects on alertness, comfort, satisfaction, and safety.

BACKGROUND: Lighting is one of the workplace factors that can relevantly impact workers' health, performance, safety, and job satisfaction. Brightness, natural light and color temperature are the factors that affect the quality of lighting. This study involved subjective and objective evaluation of office lighting and its effects on workers' alertness, comfort, satisfaction, safety, and performance in a prominent government office. METHODS: Visual comfort, alertness, performance, safety and satisfaction were assessed subjectively using the questionnaires and rating scales. Moreover, illuminance, color temperature of light sources, and natural light availability were evaluated objectively. RESULTS:  The findings of this study indicated that the use of natural light in the workplace could increase the illuminance and color temperature of light in the workplace and improve alertness, visual comfort, satisfaction and worker's preference. Conclusions: To improve the quality of lighting in the workplace, factors affecting it, such as the color temperature and the availability of natural light, should be considered.