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Caitlin Murphy, David Nguyen-Tri, Rand Allabade, Jocelyn Faubert, Olga Overbury; Postural Balance in Individuals with Central Vision Loss. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1951.
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© ARVO (1962-2015); The Authors (2016-present)
Vision is second only to the vestibular system in terms of its contribution to balance. There are several theories about the roles that central and peripheral vision play in maintaining postural balance. It is well known that visually impaired people (VIPs) often have diminished balance abilities. Central vision loss, such as that in age-related macular degeneration (AMD), forces individuals to rely more on their remaining peripheral vision. This can result in lower visual acuity and less stable fixation. Previous research from our lab has shown that VIPs with less stable fixation are less confident in their balance abilities and more likely to fall. The purpose of this research is to explore the impact of central vision loss on postural balance.
VIPs with a visual acuity of 20/400 or better and a diagnosis of AMD were recruited for this study. Fixation stability and eccentricity of a preferred retinal locus (PRL) were measured using the Optos Optical Coherence Tomographer/Scanning Laser Ophthalmoscope (OCT/SLO). The Timed Up-and-Go (TUG) and the Activities-specific Balance Confidence (ABC) Scale were used as functional balance measures. Postural response to a virtual tunnel was assessed using the CAVE system, a fully immersive virtual environment. A magnetic motion tracking system was used to measure postural reactivity to a visual stimulus that oscillated at several frequencies (0.125Hz, 0.25Hz and 0.5Hz).
To date, the results of this ongoing study seem to agree with that of our previous results on fixation stability and functional balance. Those with more stable fixation are more confident in their balance abilities and have better TUG scores. As of yet, there appears to be no relationship between fixation stability or eccentricity of the PRL and postural response as determined by the CAVE. Furthermore, the response patterns of participants to the three oscillation frequencies of the virtual tunnel are inconsistent.
Fixation stability may play a role in balance confidence and mobility tasks like the TUG that require participants to fixate on a target. However, it appears that it likely does not play a significant role in postural stability. The inconsistent nature of the participants’ response to the virtual tunnel indicates that some aspect of AMD may influence postural balance. Further study is required to determine that parameter.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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