Comet assay analysis of single-stranded DNA breaks in circulating leukocytes of glaucoma patients

PURPOSE: To investigate the amount of single-stranded DNA breaks in circulating leukocytes of primary open-angle glaucoma (POAG) patients. METHODS: A comparative quantification of DNA breaks was performed in circulating leukocytes of POAG patients and healthy controls. The following groups of subjects were compared: (1) POAG patients having primary vascular dysregulation (PVD), (2) POAG patients without PVD, (3) healthy controls with PVD, and (4) healthy controls without PVD. The damage to DNA resulting in single-stranded breaks was assessed by means of the alkaline comet assay in which the damaged DNA migrates out of the nucleus forming a tail, which can be quantified using image analysis. Damage was quantified as the comet tail moment, which represents the extent of DNA damage in individual cells. RESULTS: Leukocytes of POAG patients exerted a significantly higher amount of comet tails, which are indicative of DNA damage, in comparison to control leukocytes (p>0.001). DNA breaks occurred particularly in the subgroup of POAG patients with PVD in comparison to glaucoma patients without PVD (p=0.002). In the control group, there was no significant difference between controls with PVD and controls without PVD (p=0.86). CONCLUSIONS: POAG patients with PVD have a significantly higher rate of DNA breaks than both POAG patients without PVD and healthy controls with and without PVD.