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Richard P Stodtmeister, Sofie Heimann, Naim Terai, Lutz E Pillunat; Retinal venous pressure at fixed airway pressure levels.. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5726.
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© ARVO (1962-2015); The Authors (2016-present)
A weak correlation between airway pressure (AirP) and retinal venous pressure (RVP) increase was observed in a previous study in which the subjects themselves determined the AirP during the Valsalva maneuver (VM). We hypothesize that a closer correlation may be seen when the RVP is measured at fixed AirP levels.
43 healthy volunteers (table 1) were investigated. Instruments used: RVP by contact lens dynamometry (CLD). IOP by dynamic contour tonometry. AirP by aneroid manometer. Blood pressure by auscultation and aneroid manometer. Examination procedure: IOP, pupil dilation, IOP, BP, assessment of the spontaneous venous pulsation (SVP) of the central retinal vein by direct ophthalmoscopy, RVP measurement in absent SVP, measurement of IOP and RVP during enhanced AirP at 4 fixed levels of AirP: 10, 20, 30 and 40 mmHg. At each pressure level 4 CLD readings were taken and the median was calculated. The sequence of the AirP levels was randomized.
Table 2 shows the RVP, the difference RVP- IOP and the IOP before and during the VM at the fixed pressure levels. AirP before the VM is zero by definition. The values of the 4 single CLD readings maximally differed by 0.0(0.0;1.8)mmHg) [Median(Q1;Q3)] at AirP 0 mmHg. This difference rose to 3.3(1.9;5.0)mmHg at AirP 40mmHg. The RVP increase was steepest from AirP 0 mmHg to AirP 10 mmHg. Then the RVP increase flattened. RVP and AirP showed a good correlation (Spearmans ρ=0.64, p<0.05). The range of the RVP values was wide. The increase of the IOP with increasing AirP was clearly smaller than that of the RVP and was maximally 1.9 mmHg at an AirP of 40
AirP and RVP showed a good correlation. This finding is in contrast to our earlier results and may be due to the wider range of the AirP in the present study. The increase in IOP was small in comparison to results in literature. This may be explained by the RVP and IOP measurement already 3 seconds after the onset of the VM. The scatter of the 4 single CLD readings increased with the AirP during the VM which may be caused by the agitation of the subjects due to the effort in enhancing the AirP. However, the scatter was too small to cause the wide range of the RVP. It can be assumed that the variability of the venous anatomy proximal of the jugular vein may be responsible for the scatter of the RVP during the VM. Also, the interindividual variability of the compliance of these vessels may have increased this effect.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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