title: Active ocular vergence improves postural control in elderly as close viewing distance with or without a single cognitive task.
abstract: Performance of the vestibular, visual, and somatosensory systems decreases with age, reducing the capacity of postural control, and increasing the risk of falling. The purpose of this study is to measure the effects of vision, active vergence eye movements, viewing distance/vergence angle and a simple cognitive task on postural control during an upright stance, in completely autonomous elderly individuals. Participated in the study, 23 elderly subjects (73.4 ± 6.8 years) who were enrolled in a center dedicated to the prevention of falling. Their body oscillations were measured with the DynaPort(®) device, with three accelerometers, placed at the lumbosacral level, near the center of mass. The conditions were the following: eyes open fixating on LED at 20 cm or 150 cm (vergence angle 17.0° and 2.3° respectively) with or without additional cognitive tasks (counting down from one hundred), performing active vergence by alternating the fixation between the far and the near LED (convergence and divergence), eyes closed after having fixated the far LED. The results showed that the postural stability significantly decreased when fixating on the LED at a far distance (weak convergence angle) with or without cognitive tasks; active convergence-divergence between the LEDs improved the postural stability while eye closure decreased it. The privilege of proximity (with increased convergence at near), previously established with foot posturography, is shown here to be valid for accelerometry with the center of mass in elderly. Another major result is the beneficial contribution of active vergence eye movements to better postural stability. The results bring new perspectives for the role of eye movement training to preserve postural control and autonomy in elderly.
authors.affiliation: IRIS Team-Physiopathologie de la Vision et Motricité Binoculaire, CNRS FR3636 Neurosciences, UFR Biomédicale, Université Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France. Electronic address: matheron@wanadoo.fr.
authors.forename: Eric
authors.initials: E
authors.lastname: Matheron
authors.affiliation: IRIS Team-Physiopathologie de la Vision et Motricité Binoculaire, CNRS FR3636 Neurosciences, UFR Biomédicale, Université Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France.
authors.forename: Qing
authors.initials: Q
authors.lastname: Yang
authors.affiliation: IRIS Team-Physiopathologie de la Vision et Motricité Binoculaire, CNRS FR3636 Neurosciences, UFR Biomédicale, Université Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Delpit-Baraut
authors.affiliation: Association À la Découverte de l'Âge Libre (ADAL), 9 rue Edouard Pailleron, 75019 Paris, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Dailly
authors.affiliation: IRIS Team-Physiopathologie de la Vision et Motricité Binoculaire, CNRS FR3636 Neurosciences, UFR Biomédicale, Université Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France. Electronic address: zoi.kapoula@gmail.com.
authors.forename: Zoï
authors.initials: Z
authors.lastname: Kapoula
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003071:Cognition; D004215:Distance Perception; D005133:Eye Movements; D005260:Female; D005403:Fixation, Ocular; D006801:Humans; D008297:Male; D008875:Middle Aged; D004856:Postural Balance
keywords: Ageing; Distance; Double task; Postural control; Vergence; Vision