Mobility in Individuals with Moderate Visual Impairments

Abstract

This article reports the results of a study to assess variations in the indoor and outdoor locomotor mobility of 22 low vision adults. Visual acuity, visual field, and contrast sensitivity data were obtained on all participants. Participants were also videotaped while walking unfamiliar indoor and outdoor routes under normal and reduced illumination. These videotapes were viewed by orientation and mobility instructors, who recorded such incidents as stopping or contacting objects during travel. Mobility assessment data obtained from the videotapes were analyzed in relation to type and degree of visual loss. Individuals’ visual fields and contrast sensitivities were found to be related to mobility performance, whereas their visual acuities were not. Visual field and contrast sensitivity together accounted for 39 percent of the variation in mobility performance. Results of the study are discussed in regard to the importance of visual contrast sensitivity and visual field for functional acitivities such as mobility.

Novel mobility test to assess functional vision in patients with inherited retinal dystrophies

“…It has been long accepted that mobility performance is significantly influenced by the total visual field (VF) extent, such that the smaller the total field of the eye, the poorer the mobility performance . Nevertheless, mobility itself may be difficult to assess uniformly, as multiple factors contribute to the outcome . QoL also is substantially adversely affected in people with reduced mobility …”

Measuring mobility performance: experience gained in designing a mobility course

“…One of the earliest studies to examine this more closely was by Marron and Bailey, 8 who found that mobility performance was predicted by the extent of the visual field and contrast sensitivity, with visual acuity only slightly improving the predictive model. Long, Rieser and Hill 2 found similar results. More recent studies have shown that, when considered in terms of equal solid angle, central and paracentral field loss is more disabling.…”

“…The other main visual factor, which correlates with mobility, is contrast sensitivity (CS). This was found to be true when low vision due to either a variety of disorders 2,6,8,16 or a specific disorder 12,14,15,17,18 was studied.…”

“…Classically, mobility is defined as the ability of the individual to move safely and efficiently from one position to another within the environment, while orientation can be defined as the process of using vision, including residual vision and/or the remaining senses to determine one’s position in the environment 1 . Mobility is a complex function and appears to be influenced by personal factors such as aspects of cognition, vision, fear of falling, expectation, prior knowledge, vestibular and proprio‐receptor input and psychological and perceptual variables 2–4 . Environmental factors also play a role.…”

“…Environmental factors also play a role. Such factors include lighting level, the number of obstacles and their size, contrast and movement and the general complexity of the environment 2,5,6 …”