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Wulff-Dieter Ulrich, Klaus-Dieter Wernecke, Andrea Moeller, Christa Ulrich, Carl Erb; Choroidal blood flow compensates for decreases in ocular perfusion pressure in glaucoma. Invest. Ophthalmol. Vis. Sci. 2017;58(8):729.
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© ARVO (1962-2015); The Authors (2016-present)
Pulsatile choroidal blood flow (pChBF) and ocular perfusion pressure (OPP) can be measured noninvasively on both eyes simultaneously, without dilation of the pupils with the Ocular Pressure Flow Analyzer (OPFA). In a retrospective, observational clinical study we examined glaucoma patients before and after selective laser trabeculoplasty (SLT) to prove that choroidal regulation compensates for declines in OPP.
OPFA examinations before and three months after SLT of 59 patients with POAG were evaluated. Patients received 360° SLT with a total energy of 0.71 ± 6.1 mJ (Trabeculas, A.R.C., Nürnberg, Germany). The relation between OPP and the relative ocular pulse blood volume (OPV) was measured with the OPFA device (tpm, Lüneburg, Germany). The pChBF-OPP curve reveals the choroidal regulatory function and makes it possible to determine the ocular perfusion reserve (OPR), meaning the eye's autoregulatory capacity, OPP, ocular blood pressure (poc) and ocular pulse blood volumes. Comparisons between untreated glaucoma patients and SLT treated patients were proven by the t-test and the non-parametric Wilcoxon-test.
Mean values and standard deviations were summarized for IOP, ocular perfusion reserve (OPR), maximum ocular pulse blood volume (PVmax), mean ocular blood pressure (pmoc), and mean ocular perfusion pressure (OPPm).Pre-treatment SLT-treatedIOP (mm Hg) 23.35 ± 2.42 14.80 ± 2.25OPR (mm Hg) 15.34 ± 3.53 25.31 ± 5.09PV (µl/beat) 1.19 ± 0.44 0.86 ± 0.27pmoc (mm Hg) 94.89 ±10.58 65.71 ± 7.66OPPm (mm Hg) 56.94 ± 8.13 55.79 ± 8.05The ocular perfusion reserve (OPR) was significantly lower in untreated POAG patients compared to the SLT treated patients. The reduction of IOP after SLT is associated with a decline in ocular arterial blood pressure and pulsatile choroidal blood flow, meaning they returned to normal. In untreated POAG, pChBF and poc were distinctly higher, obviously due to a strong choroidal vasodilation.
The results support the hypothesis that an effective choroidal blood flow regulation does exist, which tries to maintain the OPP, particularly when IOP is elevated in glaucoma. Further investigations will be needed to clarify the importance of choroidal regulation for ocular perfusion. Is a permanent choroidal regulation necessary to guarantee an optimal OPP to secure the supply of the retina and the optic nerve with oxygen and nutrients?
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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