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Richard P Stodtmeister, Heinrich Stroehla, Eberhard Spoerl, Lutz E Pillunat; The central retinal venous pressure at a fixed airway pressure of 40mmHg. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3190. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
In a previous study, in which the subjects could determine their maximal tolerable airway pressure (AirP) during the central retinal venous pressure (CRVP) measurement, CRVP showed a low correlation with the AirP. The purpose of this study was to determine the relationship of the CRVP with a fixed AirP of 40 mmHg at which the intraocular pressure (IOP) has been determined in literature.
40 healthy volunteers as described in table 1 were investigated. Instruments used: CRVP by contact lens dynamometry. IOP by dynamic contour tonometry. AirP by aneroid manometer. Blood pressure by semiautomatic oscillatory cuff. Examination procedure: Initial IOP, pupil dilation, IOP, BP, evaluation of the spontaneous venous pulsation (SVP) of the central retina vein by direct ophthalmoscopy. Period I: Three times measurement of CRVP in quick succession at an AirP of 40 mmHg. 5 minutes break. IOP and period II like period I. 5 minutes break. IOP and period III like period I. 5 minute break. IOP, IOP at 40mmHg AirP.
The description of the CRVP and the IOP at the different time points is given in table 2. The rise in CRVP is clearly higher than the rise in IOP by the increase of the AirP. The median CRVP is lower than the AirP. The CRVP decreases from period I through period III (Friedman-test: p=0.001). The intraclass correlation coefficient (ICC) is high within the three measurement periods. The range of the CRVP at the AirP of 40 mmHg is wide. After period III the median IOP is about 2.1 mmHg lower than the median initial IOP (equal to the initial CRVP by definition in these 40 subjects) and it rises by 2.5 mmHg by the increase of AirP.
A wide range of the CRVP values up to 59 mmHg at a fixed AirP of 40 mmHg was observed in the present study. This may partially be caused by the restlessness of the patient due to the enhancement of the AirP. However, the high ICC may be taken as a sign of a high reliability of the measurement values. Thus, we may conclude that the wide range of the CRVP may be a hint at a high functional variability of the venous system in response to the fixed increase of AirP. The decrease of the CRVP from period I through period III may be interpreted as a sign of change in the compliance of the venous system by the previous enhancement of the AirP. At all time points the median CRVP is higher than the average IOP reported in the literature at 40 mmHg AirP.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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