Augmented Reality Framework to Measure and Analyze Eye-Hand Coordination in Stroke Patients with Unilateral Neglect:...

Stroke is a leading cause of disability, often accompanied by unilateral spatial neglect (USN), which severely impairs recovery. Traditional assessments like paper-pencil tests provide limited insights into behaviors and eye-hand coordination during real-world tasks. Advances in hand pose estimation and eye tracking in combination with augmented reality (AR) offer potential for data-driven assessments of naturalistic interactions.

This proof-of-concept study presents and evaluates a multimodal behavioral tracking system that captures gaze, body, and hand movements during interactions within an AR environment. Our primary goals are to (1) validate that this system can achieve robust and accurate interaction data capture in clinical settings, (2) show that the system can reliably detect known USN behavioral patterns, and (3) explore how comprehensive data can provide new understanding of eye-hand coordination deficits in USN.

We developed an AR-based assessment system using Microsoft HoloLens 2 and an external body-tracking camera to capture real-time gaze, hand, and body movements in an interactive environment. Multimodal data streams were temporally synchronized, fused, and filtered to enhance spatial accuracy and availability. Tracking performance was benchmarked against a traditional optical motion-capture system to validate reliability. In a study, 7 patients with right-brain lesions with mild to moderate USN and 8 healthy controls participated. Each performed a designed reaching task, stamping virtual sheets of paper that appeared randomly on a table. We analyzed participants' search behavior patterns to assess attentional biases and examined gaze anchoring timing during targeted reaching motions to explore potential eye-hand coordination deficits.

The fusion of hand-tracking data from the HoloLens 2 and external system reduced tracking loss from 25.7% to 2.4%, with an absolute trajectory error of 3.27 cm. The system demonstrated high usability and was well accepted by patients. Data from the control group confirmed the absence of intrinsic lateral biases in the system and task design. The USN group displayed typical search behavior through ipsilesional biases in gaze direction during visual exploration (median deviation 7.46 [1.61-9.48] deg, P<.05) and longer times to find contralesional targets (median difference 1.08 [0.20-1.80] s, P=.02). Additionally, the eye-hand coordination analysis revealed lateral differences in gaze anchoring during targeted reaching motions in the USN group, with earlier fixation on contralesional targets (median difference 112 [71-146] ms, P=.02).

The proposed AR framework provides a novel, comprehensive data-driven method for capturing interaction behavior in a controlled, yet naturalistic environment. Our results demonstrated the system's effectiveness in measuring hallmark USN symptoms, such as gaze and head orientation biases, and highlighted its potential to complement traditional assessments by offering deep insights into torso rotation and eye-hand coordination with a high resolution and accuracy. This data-driven approach shows promise for enhancing current USN assessment practices and gaining new insights into patients' behaviors.