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Abstract #10360 Published in IGR 6-1
Posture changes and subfoveal choroidal blood flow
Longo A; Geiser MH; Riva CEInvestigative Ophthalmology and Visual Science 2004; 45: 546-551
PURPOSE: To evaluate the effect of posture change on subfoveal choroidal blood flow (ChBF) in normal volunteers. METHODS: Pulsatile, nonpulsatile, and mean ChBF were measured with laser Doppler flowmetry in 11 healthy volunteers with a mean age of 32 ± 13 (SD) years. The posture of the subjects was changed from standing (90°), to supine (-8°), and back to standing, with a mechanically driven table. During the whole experimental procedure, ChBF and heart rate (HR) were recorded continuously. After 30 seconds in the standing position, the subjects were tilted to supine for approximately 30 seconds. They remained in this position for approximately two minutes, after which they were tilted back to the standing position (recovery), where they remained for approximately another two minutes. Systemic brachial artery blood pressure (BP) was measured in the baseline, supine, and recovery positions. This procedure was repeated to measure the intraocular pressure (IOP) in the different postures. RESULTS: Mean BP did not change significantly throughout the experimental procedure. As the body was tilted from standing to supine, HR decreased by 16% (p < 0.0004), IOP increased by 29% (p < 0.001), and mean ChBF increased by 11% (p < 0.01). The increase in ChBF was primarily due to an increase in the nonpulsatile component of the blood velocity. CONCLUSIONS: Based on previously reported experimental data that indicate that the ocular perfusion pressure increases less than predicted by purely hydrostatic considerations when the body is tilted from the standing to the supine position, the observed increase in ChBF suggests a passive response of the choroidal circulation to the posture change.
Dr. A. Longo, Istituto di Oftalmologia, Universita di Catania, Catania, Italy
Classification:
6.11 Bloodflow measurements (Part of: 6 Clinical examination methods)
