Eye-Tracking in Bipolar Disorder: A Methodology-Focused Narrative Review

Background and Objectives: This methodology-focused narrative review synthesizes the eye-tracking literature in bipolar disorder (BD) to evaluate the utility of such technology in identifying potential state or trait biomarkers for BD. Methods: A PubMed and Scopus search was performed from database inception to August 2026. Eligible studies included adults with BD or individuals at high-risk for BD compared with healthy controls (HCs) that used at least one quantitative eye-tracking paradigm and reported extractable quantitative outcomes. Studies were grouped into eight paradigms: free-viewing task (FVT), antisaccade (AS), prosaccade (PS), memory-guided saccade (MGS), smooth pursuit eye movements (SPEM), vergence, binocular rivalry (BR), and eye-blink rate (EBR). Findings were synthesized narratively based on study designs and outcome measures. Results: 24 studies met inclusion criteria. FVT and PS were the most frequently represented paradigms (n = 8 each), followed by AS (n = 7), BR (n = 4), and SPEM (n = 3); MGS, vergence, and EBR were each represented by one report. Findings from FVT, AS, and PS were inconsistent; the study designs, stimulus types, mood states during the study, and outcome measures of studies with these paradigms were diverse. BR alternation rate was consistently slower in BD across three studies. SPEM deficits were more closely associated with psychotic features. Evidence from single studies of MGS, vergence, and EBR limits their interpretations. Conclusions: Eye-tracking paradigms are promising tools for studying cognitive, affective, perceptual, sensorimotor, and reward-related presentations of BD. However, the field needs standardized protocols that include eye-tracking paradigms, mood states, symptom severity, outcome measures, study samples, and comparison groups to examine the utility of eye-tracking technology in BD.