Evaluation of Tear Fluid and Aqueous Humor Concentration of Clusterin as Biomarkers for Early Diagnosis of Pseudoexfoliation Syndrome and Pseudoexfoliative Glaucoma

Abstract

Purpose: Pseudoexfoliation syndrome (PEX) is an age-related disorder of the extracellular matrix characterized by the accumulation of fibrillary deposits in the anterior chamber of the eye, which leads to the development of pseudoexfoliative glaucoma (PEG). Early identification of subjects with higher susceptibility to PEX and PEG development is very important so that these conditions are managed at earlier stages, which requires that an objective biomarker is defined. Therefore, in the present study, we aimed to determine if aqueous humor and tear fluid concentrations of clusterin, an extracellular chaperone, are objective biomarkers for PEX and PEG risk. Methods: Tear fluid was obtained from 80 patients with PEG, 80 patients with PEX, and 80 controls, using Schirmer strips. Aqueous humor was also collected during cataract surgery from 12 patients with PEG, 17 patients with PEX, and 22 controls, who also gave tear samples. Clusterin concentration was determined by ELISA. Results: Clusterin concentration in aqueous humor was significantly higher in patients with PEG than in PEX cases (P = .002) and controls (P = .004). Receiver operating characteristics analysis revealed that this parameter is a robust classifier to distinguish PEG and PEX cases. Tear fluid clusterin concentrations did not differ significantly between groups. Aqueous humor and tear fluid levels of clusterin were not significantly correlated. Conclusions: In conclusion, tear fluid clusterin level in patients with PEG and PEX was determined for the first time, which showed no difference between study groups. Aqueous humor clusterin level was markedly higher in patients with PEG.