Using continuous visual stimulus tracking for detecting visual function loss due to acquired brain injury

Area of Science:

• Ophthalmology
• Neuroscience
• Medical Technology

Background:

• Acquired brain injury (ABI) can lead to homonymous visual field (VF) defects.
• Standard automated perimetry (SAP) is the gold standard for VF assessment but can be challenging for ABI patients.
• SONDA (Standardised Oculomotor and Neurological Disorders Assessment) offers a simplified perimetric task by tracking a moving stimulus.

Purpose of the Study:

• To evaluate if SONDA-based eye movement perimetry (SONDA-EMP) can detect visual function loss in patients with homonymous VF defects.
• To determine if SONDA-EMP can quantify visual function loss, correlating with SAP Mean Sensitivity (MS).
• To assess for a learning effect in SONDA-EMP performance.

Main Methods:

• Tracking performance was assessed in 16 unilateral ABI patients and compared to 36 controls.
• Participants monocularly tracked a moving stimulus (Goldmann size III) at three Weber contrasts (40%, 160%, 640%) while eye movements were recorded.
• SONDA-EMP measured the agreement between gaze and stimulus position.

Main Results:

• ABI patients showed significantly decreased tracking performance compared to controls across all contrasts (p < 0.0001).
• Tracking performance improved from 40% to 160% contrast (p < 0.0001) but not further.
• SAP MS showed moderate to strong correlations with tracking performance at 160% and 640% contrast (r=0.73, p=0.01; r=0.67, p=0.004).

Conclusions:

• SONDA-EMP is capable of detecting visual function loss resulting from ABI.
• The degree of tracking performance reduction in SONDA-EMP is dependent on the extent of visual field loss.
• No significant learning effect was observed with repeated SONDA-EMP testing.