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Wulff-Dieter Ulrich, Klaus-Dieter Wernecke, Andrea Moeller, Christa Ulrich, Konstantin E Kotliar, Carl Erb; Calculated (surrogate) ocular perfusion pressure is not the same as ocular perfusion pressure (OPP). Invest. Ophthalmol. Vis. Sci. 2018;59(9):5081.
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© ARVO (1962-2015); The Authors (2016-present)
To compare calculated (surrogate) OPP with measured (real) OPP. Hypothesis: Calculated and measured OPPs are not the same.
In a retrospective clinical study we compared the measured and surrogate OPP of 117 primary open-angle glaucoma (POAG) patients and 118 healthy subjects. OPP was measured with the Ocular Pressure Flow Analyzer, OPFA, (tpm-GmbH, Lüneburg, Germany) at the point where the central retinal artery leaves the ophthalmic artery, as evidenced by video angiography. OPP surrogate values were calculated using the conventional formulas: SOPP=SBBP-IOP; DOPP=DBBP-IOP; MOPP=2/3 [DBBP + 1/3(SBBP-DBBP)] – IOP. The MOPP of the measured SOPP and DOPP was calculated as usually: MOPP=DOPP+1/3 (SOPP-DOPP).
Comparison of surrogate with measured OPP (mean ± SD, mmHg):117 untreated POAG patientsMeasured data Surrogate dataSOPP 87.3±12.8 SOPP 127.3±20.9DOPP 40.2± 7.2 DOPP 68.6±14.6MOPP 55.9± 8.0 MOPP 50.9±10.1118 healthy subjectsMeasured data Surrogate dataSOPP 77.3± 9.3 SOPP 113.4±12.2DOPP 39.1± 5.9 DOPP 67.6± 8.7MOPP 51.8± 6.1 MOPP 49.9± 5.9SOPP=systolic OPP, DOPP=diastolic OPP, MOPP=mean ocular PP.Despite major differences between measured and calculated data there were close correlations. For both groups (POAG patients and healthy subjects) intraclass-correlation showed a moderate to good consistence, but a bad absolute agreement, revealed as substantial bias in Bland-Altman-plots. The paired Wilcoxon-Test came to highly significant differences between measured and calculated data.
The differences between measured OPP and calculated surrogate values are substantial in both POAG patients and healthy subjects. The close correlation between calculated surrogate values and measured real ocular data reveals that ocular circulation depends strongly on systemic blood pressure. Surrogate values are not the same as ocular perfusion pressures and therefore no indicator of local ocular (retinal and choroidal) blood flow regulation. Surrogate values and measured OPP are not identical.
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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