Patterns of Pupillary Activity During Binocular Disparity Resolution

Area of Science:

• Neuroscience
• Ophthalmology
• Vision Science

Background:

• Understanding the dynamic interplay between eye movements and pupil responses is crucial for visual neuroscience.
• Previous models suggest a dual interaction control mechanism for vergence and pupil size, but detailed dynamic coordination patterns remain underexplored.

Purpose of the Study:

• To investigate the dynamic coordination between disconjugate vergence eye movements and pupil size.
• To identify and characterize different synkinetic response patterns between vergence and pupil size.
• To evaluate these findings in the context of existing visual control models.

Main Methods:

• 52 healthy subjects performed binocular disparity step and sinusoidal pursuit tasks in a virtual reality environment.
• Eye movements and pupil area were recorded using video-oculography at 100 Hz.
• Pupil size data were normalized, and a modified Gath-Geva clustering algorithm analyzed the dynamic relationship between vergence angle and pupil size.

Main Results:

• Subjects exhibited robust vergence eye movements with high-fidelity sinusoidal responses.
• Two distinct synkinetic patterns were identified: a dominant 'near response' (pupil constriction during convergence, dilation during divergence; ~80% of data) and a novel opposite pattern (~15% of data).
• Pupil size intercepts varied between these two patterns, and hippus-like pupil movements sometimes accompanied vergence.

Conclusions:

• The dynamic relationship between vergence and pupil size involves at least two distinct synkinetic patterns.
• Findings suggest a dynamic switching of vergence-related information influencing pupil control, with pupil aperture resetting at zero vergence.
• The newly described synkinetic pattern challenges current understanding and may necessitate model refinement.