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. 2013 Dec 6;8(12):e82351.
doi: 10.1371/journal.pone.0082351. eCollection 2013.

Optic nerve head blood flow autoregulation during changes in arterial blood pressure in healthy young subjects

Agnes Boltz  1 , Reinhard Told, Katarzyna J Napora, Stefan Palkovits, René M Werkmeister, Doreen Schmidl, Alina Popa-Cherecheanu, Gerhard Garhöfer, Leopold Schmetterer
Affiliations

Optic nerve head blood flow autoregulation during changes in arterial blood pressure in healthy young subjects

Agnes Boltz et al. PLoS One. .

Abstract

Aim: In the present study the response of optic nerve head blood flow to an increase in ocular perfusion pressure during isometric exercise was studied. Based on our previous studies we hypothesized that subjects with an abnormal blood flow response, defined as a decrease in blood flow of more than 10% during or after isometric exercise, could be identified.

Methods: A total of 40 healthy subjects were included in this study. Three periods of isometric exercise were scheduled, each consisting of 2 minutes of handgripping. Optic nerve head blood flow was measured continuously before, during and after handgripping using laser Doppler flowmetry. Blood pressure was measured non-invasively in one-minute intervals. Intraocular pressure was measured at the beginning and the end of the measurements and ocular perfusion pressure was calculated as 2/3*mean arterial pressure -intraocular pressure.

Results: Isometric exercise was associated with an increase in ocular perfusion pressure during all handgripping periods (p < 0.001). By contrast no change in optic nerve head blood flow was seen. However, in a subgroup of three subjects blood flow showed a consistent decrease of more than 10% during isometric exercise although their blood pressure values increased. In addition, three other subjects showed a consistent decline of blood flow of more than 10% during the recovery periods.

Conclusion: Our data confirm previous results indicating that optic nerve head blood flow is autoregulated during an increase in perfusion pressure. In addition, we observed a subgroup of 6 subjects (15%) that showed an abnormal response, which is in keeping with our previous data. The mechanisms underlying this abnormal response remain to be shown.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exists.

Figures

Figure 1
Figure 1. Effect of handgripping on ocular perfusion pressure (OPP, panel A) and optic nerve head blood flow (ONH blood flow, panel B).
Three periods of isometric exercise were scheduled for each subject (n=39). Data are presented before during and after the 1st handgripping experiment (BL1, HG1, RE1), before during and after the 2nd handgripping experiment (BL2, HG2, RE2) and before during and after the 3rd handgripping experiment (BL3, HG3, RE3). In the box-and-whisker blots the medians, standard deviations (SD) and 1.96 ± SDs are shown.
See this image and copyright information in PMC

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