Ocular blood flow alteration in glaucoma is related to systemic vascular dysregulation

Aims: To investigate the source of ocular blood flow alterations in glaucoma. Methods: In 56 patients with open angle glaucoma, blood flow parameters were obtained from both eyes in the ophthalmic and central retinal artery by means of colour Doppler imaging, as well as in the choroidal circulation and the neuroretinal rim of the optic nerve by means of laser Doppler flowmetry. Based on these haemodynamic parameters, a cluster analysis (two groups) was performed and differences with regard to risk factors were assessed between clusters. Results: Ocular blood flow data in the two clusters indicated that the two groups (cluster 1 = 26 patient with higher blood flow values; cluster 2 = 30 patients with lower blood flow values) differed mainly in choroidal and optic nerve blood flow. No differences in sex distribution, propensity to have normal tension glaucoma, age, endothelin-1 plasma levels, visual field damage, intraocular pressure, or systemic blood pressure parameters were observed between the two clusters. However, 12 patients (46%) from the cluster with high ocular blood flow values showed a vasospastic response in nailfold capillaroscopy, while such a response was observed in 24 patients (80%) of the cluster with low ocular blood flow values. This difference in vasospastic propensity was statistically significant (p = 0.0121). Conclusions: Ocular blood flow alterations in glaucoma patients seem, at least partly, to be related to a systemic vascular dysregulation.