Clinical Assessment of Functional Movement in Adults with Visual Impairments.

Adults with visual impairments (that is, those who are blind or have low vision) have significantly more health risks than do sighted adults because of a number of factors, including the lower mineral density of their femoral neck bones, which is indicative of reduced weight-bearing exercise; their lesser maximal strength; and their higher rates of stroke, osteoporosis, depression, hypertension, heart disease, arthritis, diabetes, and falls (Crews & Campbell, 2001; Uusi-Rasi, Sievanen, Rinne, Oja, & Vuori, 2001). A contributing factor is that individuals who are visually impaired are less physically active than are sighted individuals (Crews & Campbell, 2001). These factors play a significant role in the quality of life of persons who are visually impaired and can affect their independent movement. The physiological changes in addition to the loss of vision to preview the environment can result in decreased movement and increased restrictions on movement. During the aging process, balance and overall mobility are affected as people lose some of their ability to use vision, proprioception, and vestibular information (Lusardi, Pellecchia, & Schulman, 2003). However, the movement of individuals who are visually impaired may diminish much earlier because of changes in behavior (the adoption of a more sedentary lifestyle); if these changes in behavior are not reversed, they could lead to a reduced quality of life as the individuals continue to age and experience a greater incidence of falls or frailty late in life. The relationship or impact of the visual, somatosensory (proprioceptive), and vestibular systems on mobility for these individuals has not been sufficiently addressed. The purpose of this investigation was to investigate the movement of adults with visual impairments using two common clinical measures to gain a better understanding of the impact of vision loss on movement and health in adults who are visually impaired. Documentation of this information is an important step in understanding the functional limitations resulting from vision loss and the eventual development of interventions and rehabilitation programs to remediate those limitations. METHOD Participants The 15 participants with visual impairments aged 20-58 were matched with 15 sighted adults by age and gender. Their visual acuity equaled or exceeded the U.S. definition of legal blindness. The participants demonstrated variability in the degree, etiology, and age of onset of their vision loss. As a group, they were active-that is, independent (all were able to travel independently with long canes) and proficient in their ability to move within their environment. The participants' visual status was divided into low, medium, and high on the basis of their level of visual functioning, which is consistent with the classification used for athletes who are blind (United States Association of Blind Athletes, 2006). The four participants in the B1 category had no light perception, the nine participants in the B2 category had the ability to see light and shapes and an acuity of up to 20/600 and a visual field of less than 5 degrees, and the two participants in the B3 category were able to recognize hand movements up to and including 20/200 acuity and had a visual field of up to 20 degrees. Demographic profiles of the participants are presented in Table 1, and data on the individual participants are presented in Table 2. Procedures Prior to testing, all the procedures were explained to and practiced with the participants, so they had a clear understanding of the requirements of the tasks and had the best opportunity to complete the trials successfully. Consent was obtained from each participant, and the protocol used was approved by the University of Georgia institutional review board. The timed up-and-go and 30-second sit-to-stand protocols were used for this study. The timed up-and-go test, which was performed to assess functional balance, mobility, and strength, is often used by clinicians because it is easy to administer, low in cost, and functionally relevant. …