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P. Galambos, J. Vafiadis, M. Klemm, S. Vilchez, L. Wagenfeld, E.T. Matthiessen, G. Richard, O. Zeitz; Differences in the Autoregulatory Control of the Optic Nerve Head Perfusion in Response to Postural Changes in Normal Tension Glaucoma Patients and Healthy Volunteers . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3905.
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Purpose: An altered autoregulation of the optic nerve head perfusion has been discussed as a possible pathogenic factor in normal tension glaucoma (NTG). The aim of the present study was to investigate the capacity of the autoregulatory system to compensate for the effects of a postural change on the microcirculation of the optic nerve head in NTG patients and healthy volunteers. Methods: Peak systolic velocity (PSV) and end–diastolic velocity (EDV) of the ocular blood flow in the short posterior ciliary artery supplying the optic nerve head were measured 10 minutes after a postural change from the sitting, to a supine and 30°–upright–position with Color Doppler Imaging (Siemens Elegra, 7.5 MHz). Before the Doppler measurements systolic and diastolic blood pressure levels in each body position were recorded. Results: In the NTG group (n=20) PSV was 8.6±0.5cms–1 in the sitting position. It increased to 11.0±0.8cms–1 in the supine and 11.2±0.8cms–1 in the 30°–position. In the control group (n=20) PSV changed from 11.4±0.8cms–1 (sitting) to 12.3±0.9cms–1 (supine) and 11.3±0.9cms–1 (30°–position). EDV in the NTG group was 2.2±0.3cms–1 in the sitting, 3.8±0.4cms–1 in supine and 3.6±0.3cms–1 in the 30°–position. In the control group the EDV changed from 3.3±0.3cms–1 (sitting) to 4.0±0.4cms–1 (supine) and 3.8±0.4cms–1 (30°–position). The alteration in PSV and EDV from the sitting to the supine and 30°–position was statistically significant only in the NTG–group (p<0.05). No significant difference in systolic and diastolic blood pressure levels following postural change were found in both groups at the time of the Doppler measurements. Conclusions: In NTG–patients but not in healthy volunteers a significant alteration in the local perfusion of the optic nerve head can be detected 10 minutes after a postural change from the sitting to a supine and 30° body position. Since this alterations are not reflected in a change of the systemic blood pressure levels a deficiency in the autoregulatory control of the optic nerve head perfusion can be assumed.
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