Three-dimensional binocular eye-hand coordination in normal vision and with simulated visual impairment

Area of Science:

• Neuroscience
• Ophthalmology
• Human motor control

Background:

• Sensorimotor coupling improves visual tracking of hand movements in the fronto-parallel plane.
• The role of sensorimotor coupling in vergence eye movements and its resilience to visual impairments remains unclear.

Purpose of the Study:

• To investigate if sensorimotor coupling enhances vergence eye movements for tracking objects in depth.
• To determine if this coupling can overcome symmetric or asymmetric binocular visual impairments.

Main Methods:

• Human observers tracked targets moving horizontally or in depth.
• Target movement was either self-generated or a delayed repetition of a previous hand movement.
• Visual impairments were simulated using asymmetric or symmetric binocular blur.

Main Results:

• Tracking accuracy was higher for self-generated movements across all conditions.
• Motor signals improve both vergence and horizontal eye movement accuracy.
• Asymmetric blur impacted horizontal tracking less than symmetric blur but equally impaired depth tracking.

Conclusions:

• Sensorimotor coupling significantly enhances oculomotor control for both horizontal and depth tracking.
• Hand-eye coordination can partially compensate for visual impairments, suggesting potential therapeutic applications.
• A critical blur threshold exists beyond which tracking accuracy is compromised, regardless of blur symmetry.