Abstract
The impairment of retinal vascular autoregulation can be an early manifestation of many systemic and ocular diseases. Therefore, quantifying retinal vascular autoregulation in a non-invasive manner is very important. This study evaluated the effects of a Valsalva maneuver (VM)-induced blood pressure increases on retinal vascular autoregulation. Parafoveal and peripapillary retinal vessel density were measured with optical coherence tomography angiography before (baseline) and 5 s after each subject completed a VM (Phase IV [VM-IV]). Hemodynamic parameters and intraocular pressure (IOP) were examined. Blood pressure (systolic, diastolic, and mean arterial) and ocular perfusion pressure significantly increased during VM-IV, but IOP and heart rate (HR) did not change. The VM-induced blood pressure overshoot significantly decreased parafoveal (8.43%) and peripapillary (1.57%) perfused retinal vessel density (both P < 0.001). The response in the parafoveal region was greater than that in the peripapillary region (P < 0.001), and was age-dependent (r = 0.201, P < 0.05). Foveal avascular zone area detectable with OCTA significantly increased from baseline by 6.63% during VM-IV (P < 0.05). Autoregulatory responses to a VM did not show gender-related differences in either retinal region. The autoregulation of retinal vessels may vary in different regions of the fundus. Optical coherence tomography angiography could be a useful method for evaluating the autoregulation of the retinal vascular system.
Highlights
Retinal vessel autoregulation is a complex homeostatic process that keeps blood flow constant during changes in blood pressure (BP; Robinson et al, 1986) and blood gas concentrations
Mean SD was −0.23 ± 0.98 D, mean axial length (AL) was 23.14 ± 0.78 mm, and mean baseline intraocular pressure (IOP) was 12.62 ± 2.45 mmHg
systolic blood pressure (SBP), diastolic blood pressure (DBP), Mean arterial pressure (MAP), and Ocular perfusion pressure (OPP) significantly increased over baseline values during Valsalva maneuver (VM)-IV (All p < 0.001)
Summary
Retinal vessel autoregulation is a complex homeostatic process that keeps blood flow constant during changes in blood pressure (BP; Robinson et al, 1986) and blood gas concentrations (most notably oxygen and carbon dioxide; Fallon et al, 1985). Quantifying vascular autoregulation in a non-invasive manner is of great value for understanding, diagnosing, and treating retinal diseases associated with vascular dysregulation. The VM is frequently performed during daily activities, including heavy lifting, vomiting, straining, forceful coughing, and sneezing. Compared with other methods for changing BP, the VM is a simple way to transiently increase BP (Reinhard et al, 2001). For this reason, the VM has been used to evaluate vessel autoregulation in many studies (Reinhard et al, 2001; Castro et al, 2014)
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