What Is the Nature of the Reach and Grasp Deficit in Wet Age-related Macular Degeneration?

SIGNIFICANCE: Vision is paramount for motor actions directed toward objects. Vision allows not only the identification of objects and their shape and spatial location, but also the adaptation of our movement when it arrives on the object. These findings show that vision deficits, as in age-related macular degeneration (AMD), can lead to reaching and grasping deficits.

PURPOSE: Few studies have investigated reaching and grasping in patients with AMD. They showed a deficit in the execution of motor actions in people with AMD, even though these people do not mention difficulties in their daily lives. The purpose of this study was to understand the nature of impairments in motor actions in patients.

METHODS: We compared performance in two reach-and-grasp tasks determined by whether the participants (16 people with wet AMD and 17 age-matched control subjects) had time to look at the object before reaching and grasping it.

RESULTS: The results show that the kinematic parameters of reach-and-grasp movements do not differ between groups when participants are provided time to look at the object before the movement. In contrast, performance in terms of movement duration, acceleration time, time to reach the maximum grip aperture, and the maximum velocity differ between patients and control subjects when the object is displayed immediately before the movement.

CONCLUSIONS: The motor perturbations observed in people with AMD in previous studies seem to result from difficulties in target identification rather than from visuomotor deficits.