Standing Balance Stability and the Effects of Light Touch in Adults With Profound Loss of Vision-An Exploratory Study.
OBJECTIVE
We evaluated the postural stability of adults with inherited profound vision loss and examined the effects of touch on their balance control.


METHODS
A total of 11 severely-sight impaired patients (mean [SD] age, 51.6 [5.3] years) and 11 control subjects (mean age, 49.7 [5.3] years) participated. Postural stability was measured using a force-balance platform eyes open/closed on a firm/foam surface under 3 test conditions: no touch, light touch, and unrestricted touch (UT), where "touch" involved placing their index finger on a rigid table. Average magnitude of center of foot pressure displacement was calculated. A somatosensory ratio (SR) was used to evaluate the somatosensory contribution to balance. A repeated measures ANOVA was used to investigate the effects of touch on standing balance.


RESULTS
Patients had a significantly increased SR compared to control subjects (mean [SD] SR controls = 1.2 [0.2], patients = 1.9 [0.5]; P < 0.01). There was a significant effect of touch, vision, and surface on balance control ("touch" F = 68.1, P < 0.01; "vision" F = 20.1, P < 0.01; "surface" F = 200.8, P < 0.01). Light touch attenuated sway in patients and controls. The effects were greater in controls when their vision was removed, and greater in patients when their somatosensory system was disrupted. Light touch was as effective as UT in attenuating sway.


CONCLUSIONS
The results of this exploratory study suggest that patients with severe sight impairment show an increased somatosensory contribution to balance control compared to their normally sighted counterparts. Light touch significantly reduces sway amplitude in severely sight impaired adults when standing on the foam surface, that is, when the somatosensory system is perturbed.
NIHR Biomedical Research Centre for Ophthalmology, UCL Institute of Ophthalmology and Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom.
Aachal
A
Kotecha
NIHR Biomedical Research Centre for Ophthalmology, UCL Institute of Ophthalmology and Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom 2UCL Institute of Ophthalmology, University College London, London, United Kingdom.
Andrew Royston
AR
Webster
UCL Institute of Ophthalmology, University College London, London, United Kingdom.
Genevieve
G
Wright
NIHR Biomedical Research Centre for Ophthalmology, UCL Institute of Ophthalmology and Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom 2UCL Institute of Ophthalmology, University College London, London, United Kingdom.
Michel
M
Michaelides
NIHR Biomedical Research Centre for Ophthalmology, UCL Institute of Ophthalmology and Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom.
Gary Stuart
GS
Rubin