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The 2009 Consensus of the World Glaucoma Association1 focused on the growing evidence suggesting ocular blood flow and perfusion pressure are related to glaucomatous optic neuropathy.1 Recent data have suggested systemic and localized vascular dysfunction may be related to glaucoma pathology. Mozaffarieh et al. (238) present data on the relationship between optic nerve head (ONH) and finger blood flow measured by nailfold capillaromicroscopy in subjects with and without a primary vascular dysregulation (PVD). ONH blood flow was found to be significantly related to finger blood flow in subjects with PVD (p < 0.01), but not in subjects without a PVD. Subjects with PVD also had a signify cantly lower (p < 0.01) finger skin temperature in comparison to those without PVD. The authors conclude this might be an indirect sign of a disturbed autoregulation of ocular blood flow in subjects with PVD. The study data and correlations appear robust and the division of patients into PVD and non-PVD by both nailfold capillaromicroscopy and detailed history makes the division more accurate. One concern is the small sample size (15 subjects with PVD and in 24 subjects without PVD) and that the PVD group contains several glaucoma patients, but the PVD group contains no glaucoma patients. Although the authors mention that there was no difference between glaucoma and non-glaucoma PVD+ patients, there could still be confounding factors.
No single methodology can provide information on blood flow in allrelevant ocular vascular bedsThe lack of statistical difference in diastolic blood pressure between the groups does not necessarily mean that it cannot influence the ONH-finger blood flow relationship and this should be considered in the statistical model. It is also important to consider that, currently, no single methodology can provide information on blood flow in all relevant ocular vascular beds. The authors present interesting information tying together systemic vascular disturbances and ONH circulation, but these relationships should be confirmed using several methodologies evaluating multiple ocular vascular beds and with a larger sample population of glaucoma patients.