Endothelin-1 plasma levels and vascular endothelial dysfunction in primary open angle glaucoma

AIMS: To assess the relationship between endothelial dysfunction, endothelin 1 (ET-1) plasma levels and subclinical inflammation in primary open angle glaucoma (POAG) patients. MAIN METHODS: We enrolled 40 POAG patients with progressive visual field damage, although well controlled intraocular pressure (IOP) and compared to age and sex matched healthxy subjects. Each patient underwent an ophthalmological examination, a standard achromatic perimetry (SAP), blood sampling to assess ET-1 plasma levels, an objective assessment of cellularity within the anterior chamber (FLARE) and measurement of flow mediated dilation (FMD) with high resolution 2-dimensional ultrasonographic imaging of the brachial artery. KEY FINDINGS: At baseline, POAG patients, compared to healthy controls, showed an increase of ET-1 plasma levels: 2.83 ± 0.28 pg/ml vs. 1.75 ± 0.25 pg/ml (p<0.001), lower FMD values 4.46 ± 1.28% vs. 13.18 ± 2.80% (p<0.001) and increased FLARE values 9.98 ± 0.97 photons/ms vs. 5.87 ± 0.64 photons/ms (p<0.001). A follow up after 1 year revealed a further increase of ET-1 plasma levels (to 3.68 ± 0.60; p<0.001) and decrease of FMD (3.52 ± 1.28; p>0.001). SIGNIFICANCE: The increase of ET-1 in POAG patients is related to vascular dysfunction (r=0.942; p=0.001) and vascular dysfunction is related to sub-clinical intraocular inflammation (r=0.968; p=0.001). Thus ET-1 and vascular dysfunction related to sub-clinical inflammation may play a key role in determining a progressive visual field damage in POAG patients who present a well-controlled IOP.