Chronic ischemia of the retina and the optic nerve head seems of importance especially in patients with normal-tension glaucoma (NTG). The purpose of this study was to examine the retinal hemodynamics in patients with NTG.
Patients: Twenty-five patients with NTG were examined (3 weeks washout period) in this study (age 58 +/- 16 years). The arteriovenous passage (AVP) time and arterial and venous diameters from scanning laser fluorescein angiograms were evaluated by means of digital image analysis.
Results: The AVP time in patients with NTG (2.78 +/- 1.1 s) was significantly prolonged (P < 0.0001) compared with healthy subjects (1.58 +/- 0.4 s). No significant correlation was found between arterial and venous diameters, intraocular pressure, blood pressure or calculated perfusion pressure and retinal arteriovenous passage time.
Conclusion: Patients with NTG showed prolonged retinal passage, which could cause chronic hypoxia. This prolongation of circulation is not correlated with any of the clinical parameters. Thus, a circulatory defect might be a primary factor in the pathogenesis of NTG.