Microvascular endothelial function and primary open angle glaucoma

PURPOSE: To determine the role of microvascular endothelial dysfunction as risk factor for primary open angle glaucoma. METHODS: A cross-sectional study was conducted involving 114 Malay patients with POAG seen at the eye clinic of Hospital Universiti Sains Malaysia. Patients aged between 40 and 80 years who were diagnosed with other types of glaucoma, previous glaucoma filtering surgery or other surgeries except uncomplicated cataract surgery and pterygium surgery were excluded. A total of 101 patients who were followed up for dry eyes, age-related cataracts or post cataracts extraction surgery were recruited as control subjects. Those with family history of glaucoma or glaucoma suspect were excluded. Microvascular endothelial function was assessed using laser Doppler fluximetry and the process of iontophoresis. Iontophoresis with acetylcholine (ACh) and sodium nitroprusside (SNP) was used to measure microvascular endothelium-dependent and endothelium-independent vasodilatations, respectively. RESULTS: In general, POAG patients demonstrated lower ACh% and ACh(max) values compared with controls. There was significant difference in microvascular endothelial function [ACh%: mean, 95% confidence interval = 503.1 (378.0, 628.3), and ACh(max): mean, 95% confidence interval = 36.8 (30.2, 43.5)] between primary open angle glaucoma cases (p < 0.001) and controls [ACh%: mean, 95% confidence interval = 1378.4 (1245.4, 1511.3), and ACh(max): mean, 95% confidence interval = 79.2 (72.1, 86.2)]; this difference remained significant even after controlling for potential confounders. Similar difference was also found in SNP% and SNP(max) between POAG and controls (p < 0.001). Age and diastolic blood pressure were inversely correlated with microvascular endothelial function. CONCLUSION: There was an impairment of microvascular endothelial function and endothelial-independent vasodilatation in POAG patients. Microvascular endothelial function is a potential risk factor for POAG.