Regulation of Optic Nerve Head Blood flow in Normal Tension Glaucoma Patients

Abstract

The LDF parameters, measured in the ONH, did not indicate an abnormal Fonh regulation in response to an increase of the PPm in either normal subjects or NTG patients. The maintenance of constant blood flow is achieved by an increase in local vascular resistance. Our data show a greater percent increase in vascular resistance in the NTG patients compared to the normal subjects for a similar percent increase in PPm in both groups during squatting. This suggests some alteration of the vessel tone regulatory mechanisms in NTG patients.

Continuous Response of Optic Nerve Head Blood Flow to Increase of Arterial Blood Pressure in Humans

“…34 The data in our 14 volunteers demonstrate that the increase of F in response to the increase of the OPP during handgrip is significantly less than predicted for a passive vascular system, indicating the presence of blood flow autoregulation in the ONH of young, healthy subjects, thus confirming previous reports by others. 2,3,7,15 As an index of the efficiency of the autoregulation process, we calculated a closed-loop gain, G at a number of discrete values of the OPP. For the 14 subjects, a mean value of G was found to be 0.7 6 0.07, which represents an efficient autoregulation, since a value of G ¼ 1 corresponds to a process in which F remains constant and equal to the baseline flow in spite of a change in the OPP and a G ¼ 0 corresponds to proportional increases of F and OPP (passive system-i.e., no change in R).…”

“…[1][2][3][4][5][6][7] Decreases of the OPP were induced by increasing the IOP, keeping the systemic arterial blood pressure (BP) constant. Increases of OPP were obtained by decreasing the IOP, 8 keeping the BP constant, or by increasing BP by means of either dynamic or static exercises, such as isometrics.…”

Ocular blood flow assessment using continuous laser Doppler flowmetry

“…2004a, 2004b), of changes in PP m and of drugs on these parameters in glaucoma patients (Pournaras & Riva 2001; Fuchsjäger‐Mayrl et al. 2004; Pournaras et al. 2004a, 2004b;Weigert et al.…”

“…The effect of aging, age‐related macular degeneration and choroidal neovascularization have been reported (Grunwald et al. 1998a, 1998b, 1998c; Pournaras et al. 2004a, 2004b, 2006).…”

Prostanoids in the Therapy of Glaucoma

“…Satilmis et al (47) made the important finding that a decrease in ocular blood flow has a predictive value similar to that of an increased IOP. In addition, there is evidence of involvement of ocular vascular dysfunction in the pathogenesis of glaucoma (15,43). Thus, an improvement in ocular blood flow is thought to be a meaningful approach to glaucoma therapy.…”