Task-Evoked Pupillary Dynamics Are Altered in Post-COVID Syndrome

Area of Science:

• Neuroscience
• Ophthalmology
• Cognitive Science

Background:

• Persistent cognitive complaints like fatigue and impaired concentration are common in Post-COVID syndrome (PCS).
• Objective markers for cognitive dysfunction in PCS are currently lacking.
• Pupillary oscillation metrics (IPA, LHIPA) are emerging as non-invasive indicators of cognitive load and autonomic regulation.

Purpose of the Study:

• To investigate the Index of Pupillary Activity (IPA) and Low/High Index of Pupillary Activity (LHIPA) in a large cohort of PCS patients versus healthy controls.
• To assess pupillary dynamics as potential objective markers for cognitive dysfunction in Post-COVID syndrome.

Main Methods:

• A cross-sectional study involving 397 PCS patients and 129 healthy controls.
• Participants performed a virtual reality stereoscopic task at varying difficulty levels while eye tracking data was collected.
• Continuous pupillometry data were analyzed to calculate IPA and LHIPA, with statistical models adjusting for age, sex, and task difficulty.

Main Results:

• Both IPA and LHIPA were significantly lower in PCS patients compared to controls across all task difficulties.
• Adjusted models confirmed lower overall IPA and LHIPA in PCS patients.
• Both indices showed an inverse association with task difficulty, with higher values at lower difficulties.

Conclusions:

• Post-COVID syndrome is associated with reduced IPA and LHIPA during cognitive tasks.
• These findings suggest altered task-related pupillary dynamics, reflecting impaired cognitive-load processing and autonomic regulation in PCS.
• LHIPA, and potentially IPA, may serve as objective measures for assessing task-related pupillary alterations in Post-COVID syndrome.