Abstract

P 112

Influence of surgical IOP reduction after deep sclerectomy on retrobulbar bloodflow in different body positions

Claudia Rebel, Peter Galambos, Oliver Zeitz, Lars Wagenfeld, Ralf Praga, Anne Wiermann, Gisbert Richard, Maren Klemm
Klinik und Poliklinik für Augenheilkunde, Universitätsklinikum Hamburg-Eppendorf, Hamburg

Objective
Besides an elevated intraocular pressure (IOP) as the main risk factor, glaucoma progression has been associated with various deficiencies in the vascular supply of the optic nerve head. Aim of the present study was to proof a positive correlation between the effects of IOP lowering on retrobulbar blood flow in different body positions.
Methods
Intraocular pressure (IOP) as well as peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistance index (RI) in the short posterior ciliary artery (SPCA) and central retinal artery (CRA) were recorded by Colour Doppler Imaging (CDI) in 25 glaucoma patients in a sitting and a lying body position before and four weeks after deep sclerectomy. Differences of pre- and postoperative blood flow measurements were correlated to IOP reduction (Spearman’s correlation coefficient).
Results
Four weeks after deep sclerectomy IOP was significantly lowered from 16.0 (±0.8) mmHg to 13.3 (±0.7) mmHg (P=0.01). A positive correlation was seen in IOP reduction and blood flow change in the SPCA in PSV (R: 0,347; p: 0,07) and EDV (R: 0,34; p: 0,077) (not significant) and in the CRA in EDV (R: 0,449; p: 0,016) und RI (R: 0,510; p: 0,006) (significant) in a lying position. No correlation was seen in a sitting position.
Conclusions
There seems to be an increase in retrobulbar blood flow velocities in SPCA and CRA depending on IOP in a lying body position. This effect was not statistic significant in all observed parameters and was not seen in a sitting position. Hydrostatic forces probably affect blood flow regulation in a sitting position that impairs the effect of IOP lowering on retrobulbar blood flow. These results are another hint to the influence of ocular blood flow on IOP as well as on the regulatory capacity of ocular vessels in glaucoma patients.

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