Impact of contrast sensitivity on driving behaviors in individuals with moderate-to-severe glaucoma

Purpose: This study aimed to investigate the relationship between contrast sensitivity (CS) and driving performance in individuals with moderate to severe glaucoma, using the Pelli–Robson (PR) chart and Spaeth/Richman Contrast Sensitivity (SPARCS) test. Design: Cross-sectional observational study. Methods: Setting: A hospital-based study was conducted in a multi-specialty tertiary care institute. Study Population: Forty-five non-professional drivers (90 eyes) diagnosed with moderate-to-severe glaucoma using Hodapp–Anderson–Parrish classification. Mean age (± standard deviation, in years) was 61.76 ± 10.02 with a significant male preponderance (97.8%). Observation Procedures: Participants underwent a comprehensive clinical assessment, and CS was assessed using both the PR chart and SPARCS. Driving-related parameters were evaluated using the Driving Habits Questionnaire, which assessed driving difficulty, driving space, and dependency on others. Statistical analyses were performed to identify correlations between CS scores and driving parameters. Primary Outcome: Patients with lower peripheral contrast experienced significant driving-related difficulties. Results: Significant correlations were observed between CS and driving behaviors in the worse eye. Lower peripheral SPARCS scores (particularly upper and lower right quadrants; ρ = 0.35–0.51, P < 0.05) were associated with reduced driving space (ρ = 0.44–0.50) and increased dependency (ρ = −0.32) and lower right scores ( ρ = −0.32, P = 0.035). Driving difficulty scores showed positive correlations with SPARCS upper right quadrant ( ρ = 0.34, P = 0.023) and lower right quadrant scores ( ρ = 0.51, P < 0.001). Driving space scores were positively correlated with PR ( ρ = 0.33, P = 0.027) and total SPARCS scores. Conclusion: CS, especially in peripheral regions, is significantly associated with driving difficulties, reduced driving space, and dependency on others in individuals with glaucoma. The worse eye’s CS measures have a stronger correlation with these driving-related factors. Clinical Implications: SPARCS correlates with structure and behavior, making it a holistic functional biomarker. Peripheral CS loss predicts functional self-regulation even before driving cessation. CS assessment could enhance the understanding of driving capabilities and safety, guide interventions, and driving restrictions more effectively to improve patient safety on the road.