ObjectiveTo investigate the effect of intraocular lens (IOL) glistenings on visual performance and evaluate a new glistenings grading methodology.Methods and AnalysisThirty-four patients (34 eyes) were recruited. Corrected distance visual acuity (CDVA), mesopic gap acuity (MGA), functional contrast sensitivity (FCS) and forward light scatter were measured (Advanced Vision and Optometric Tests, City Occupational, London, UK). The IOL centre was imaged and glistenings density graded by three observers using the Miyata scale and a new system. Inter-rater reliability, association between the two grading scales, and correlations between glistenings grades and visual performance parameters were evaluated.ResultsThe intraclass correlation coefficient between graders for the new grading system was 0.769 (95% Confidence Interval [CI] 0.636 to 0.868). There was a significant association between the Miyata scale and the new grading system for all graders (r_s=0.533–0.895, p≤0.001). There was no association between CDVA or MGA and glistenings grade (r_s=− 0.098, p=0.583 and r_s=0.171, p=0.359, respectively). There was no association between FCS at mesopic light levels and glistenings grade (r_s=−0.032, p=0.864), or the straylight parameter and glistenings grade (r_s=0.021, p=0.916). No association was found between the integrated straylight parameter and glistenings grade (r_s=0.078, p=0.701).ConclusionThe new glistenings grading scale was highly reproducible. In this cohort, glistenings in the same hydrophobic acrylic IOL after cataract surgery were not associated with changes in visual function, as assessed by a series of tests not previously used in glistenings research.