Background Contrast sensitivity (CS) testing can detect differences in functional vision and is highly correlated with visual performance.This study was designed to investigate the association between CS and the grading score using the lens opacities classification system (LOCS) Ⅲ as well as the association between CS and visual acuity (VA) in nuclear or cortical age-related cataract (ARC) patients.Methods A total of 270 eyes with ARC and 30 control eyes were divided into nuclear opacity (NO),nuclear color (NC),cortical cataract (C) based on LOCS Ⅲ.The CS values measured at all spatial frequencies under photopic and glare conditions that resulted in contrast sensitivity function (CSF) were evaluated,and LogMAR VA was tested with the Early Treatment Diabetic Retinopathy Study (ETDRS) chart.The correlation between CSF and LOCS Ⅲ grading scores,and between CSF and LogMAR VA were analyzed.Results Compared to the controls,CSF of the nuclear or cortical ARC significantly declined.There are significant correlation between CSF and LogMAR VA,and between CSF and LOCS Ⅲ grading scores.Compared to the VA,a stronger correlation existed between CSF and LOCS Ⅲ grading score than that of LogMAR VA and LOCS Ⅲ grading score.CS at some spatial frequencies is significantly influenced with LOCS Ⅲ grading score.Conclusions CSF significantly declined with the increasing ARC grading scores.Comparing to VA,CSF reflected the severity of cataract more comprehensively.CS at low spatial frequency is significantly influenced by ARC.Therefore,CS is more precise than VA in assessing the visual function of ARC patients.