Reaching & Grasping Deficits in Amblyopia

Dr Simon Grant City University

Host R. Coats

Reaching & Grasping Deficits in Amblyopia

Amblyopia is a common disorder which usually arises due to misalignment (squint) and/or a refractive imbalance (anisometropia) between the two eyes during the first 7-8 years of childhood. It has long been clinically defined and treated as a condition of reduced visual acuity in one (‘lazy’) eye. But an emerging consensus is that the condition should be re-classified as a disorder of binocular cortical dysfunction, which has deleterious effects on a wide range higher-level perceptual abilities, spatial attention and action control. Indeed, recent evidence shows that adults with persistent amblyopia generally produce slower/more cautious, yet less accurate, movements compared to visually-normal subjects, when performing a range of everyday activities, including reaching to grasp objects (prehension), stepping over obstacles, reading and car-driving. I will review evidence that binocular vision in normal adults usually provides important advantages over monocular viewing for the speed and accuracy of prehension movements, with vergence signals benefiting reach planning and disparity processing essential for the online control of precision grasping.  And I will present data highlighting the main deficits in reach-to-grasp planning and execution in adults with persistent amblyopia when viewing binocularly, with their affected eye, and sometimes their dominant (‘good’) eye too, suggesting generalized difficulties in visually-encoding the 3D world for goal-directed movement control and, thus, consistent with the emerging view of widespread dysfunctions in the amblyopic brain.

All seminars Wednesday at 4pm in 1.33-1,34, Psychology

for further details contact: Hannah Nash