Purpose:The aim of this study was to compare all platelet markers, especially plateletcrit (PCT, total platelet mass), in patients with and without ocular pseudoexfoliation (PEX) syndrome.Methods:One hundred six patients with ocular PEX syndrome (study group) and 106 individuals without ocular PEX syndrome (control group) were enrolled in this retrospective case-control study. The biochemical/hematological laboratory results of both the study and control groups were analyzed by a clinician blinded to the group assignments. The main outcome measures were the PCT, platelet count (PLT), mean platelet volume (MPV), and platelet distribution width (PDW).Results:The mean PCT in the study and control groups were 0.206%0.520% and 0.171%+/- 0.410%, respectively (P<0.001), and the mean PDW in the study and control groups were 16.12%+/- 1.21% and 14.68%+/- 1.40%, respectively (P<0.001). There were no differences in the MPV or mean PLT (P=0.138 and P=0.055, respectively). The PCT cutoff value was 0.180 (area under the receiver operating characteristics curve, 0.706; P<0.001; 65% sensitivity; 74% specificity).Conclusions:The PCT and PDW were significantly higher in patients with than without ocular PEX syndrome. These increased parameters may cause microvascular blood flow resistance and the heightened inflammatory response caused by excessive platelet activity, as with other cardiovascular diseases, and may also decrease aqueous humor outflow in ocular PEX syndrome.