Look into my eyes: What can eye-based measures tell us about the relationship between physical activity and cognitive performance?

•There is insufficient evidence available to make solid conclusions concerning gaze-fixation-based measures.•The current evidence on the relationships between pupillometric indices, as proxies of the noradrenergic system, acute physical exercise, cardiorespiratory fitness, and cognitive performance is mixed.•Physical training- or fitness-related changes of the cerebrovascular system (i.e., operationalized via changes in retinal vasculature) are, in general, positively associated with cognitive performance improvements.•Acute and chronic physical exercises have a positive effect on oculomotor-based measures of executive function (i.e., operationalized via antisaccade tasks).•The positive association between cardiorespiratory fitness and cognitive performance is partly mediated by the dopaminergic system operationalized via the spontaneous eye-blink rate. There is a growing interest to understand the neurobiological mechanisms that drive the positive associations of physical activity and fitness with measures of cognitive performance. To better understand those mechanisms, several studies have employed eye-based measures (e.g., eye movement measures such as saccades, pupillary measures such as pupil dilation, and vascular measures such as retinal vessel diameter) deemed to be proxies for specific neurobiological mechanisms. However, there is currently no systematic review providing a comprehensive overview of these studies in the field of exercise-cognition science. Thus, this review aimed to address that gap in the literature. To identify eligible studies, we searched 5 electronic databases on October 23, 2022. Two researchers independently extracted data and assessed the risk of bias using a modified version of the Tool for the assEssment of Study qualiTy and reporting in EXercise (TESTEX scale, for interventional studies) and the critical appraisal tool from the Joanna Briggs Institute (for cross-sectional studies). Our systematic review (n = 35 studies) offers the following main findings: (a) there is insufficient evidence available to draw solid conclusions concerning gaze-fixation-based measures; (b) the evidence that pupillometric measures, which are a proxy for the noradrenergic system, can explain the positive effect of acute exercise and cardiorespiratory fitness on cognitive performance is mixed; (c) physical training- or fitness-related changes of the cerebrovascular system (operationalized via changes in retinal vasculature) are, in general, pos