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The Effect of Dietary Nitrate Supplementation on Retinal

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The Effect of Dietary Nitrate Supplementation on Retinal The effect of dietary nitrate supplementation on retinal vessel responses in young healthy subjects Posterboard#: A0120 Abstract Number: 5725 - A0120 AuthorBlock: Naim Terai1, Fabian Helbig1, Lisa Ramm1, Richard P. Stodtmeister1, Lutz E. Pillunat1 1Ophthalmology, University of Dresden, Dresden, Germany; DisclosureBlock: Naim Terai, None; Fabian Helbig, None; Lisa Ramm, None; Richard P. Stodtmeister, None; Lutz E. Pillunat, None; Purpose In peripheral arterial disease, dietary nitrate supplementation enhances patients exercise performance via an increase in nitric oxide (NO) bioavailability and an improvement of tissue oxygenation. Therefore, the aim of the present study was to investigate whether an oral intake of inorganic nitrate in form of beetroot juice may have an impact on retinal vessel responses in young healthy subjects as a sign of an increased NO bioavailability in the endothelium of retinal vessels.Methods In a prospective, placebo-controlled randomized study, retinal vessel response was measured in 62 healthy subjects before and two hours after oral intake of either beetroot juice (group I, 200 ml) or apple juice (group II, 200 ml) as a placebo. Static and dynamic vessel analysis was performed with the Dynamic Vessel Analyzer (DVA, Imedos Systems UG). Intraocular pressure (IOP), systemic blood pressure and blood glucose level were obtained before and after oral intake of both juices.Results Mean age was 25.4 ± 2.3 years and 25.1 ± 2.8 years in group I and II with no statistical significant difference between both groups (p = 0.665). Systemic blood pressure, blood glucose level and IOP did not change significantly after supplementation of beetroot juice or apple juice. Dilatation responses of the arterioles and the venules (+ 3.84 ± 2.3 % and + 4.57 ± 2.96 %) did not change significantly after intake of beetroot juice (+ 3.76 ± 1.88 % and + 4.66 ± 2.26 %, p = 0.624 and p = 0.752). Also, the constriction responses of the arterioles (- 1.08 ± 1.18 %) did not change significantly after beetroot juice intake (- 0.990 ± 1.40 %, p = 0.310). Static vessel analysis revealed non-significant changes of the central retinal artery equivalent (197.42 ± 23.5 µm to 195.88 ± 15.1 µm, p = 0.477) and the central vein equivalent (221.19 ± 29.4 µm to 218.02 ± 17.18 µm, p = 0.848).Conclusions In the present study retinal vessel responses, as measured by the DVA, were not affected by dietary nitrate supplementation in young healthy subjects. It might be hypothesized that an unaffected endothelial function as seen in young subjects may not show any further improvement of vessel responses after additional nitrate intake. However, further studies should elucidate in how far patients with an endothelial dysfunction (e.g. glaucoma) may benefit from an nitrate supplementation.Layman Abstract (optional): Provide a 50-200 word description of your work that non-scientists can understand. Describe the big picture and the implications of your findings, not the study itself and the associated details. Retinal venous pressure at fixed airway pressure levels. Posterboard#: A0121 Abstract Number: 5726 - A0121 AuthorBlock: Richard P. Stodtmeister1, Sofie Heimann1, Naim Terai1, Lutz E. Pillunat1 1Ophthalmology, TU Dresden, Dresden, Germany; DisclosureBlock: Richard P. Stodtmeister, None; Sofie Heimann, None; Naim Terai, None; Lutz E. Pillunat, None; Purpose 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.Methods 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.Results 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 40Conclusions 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.Layman Abstract (optional): Provide a 50-200 word description of your work that non-scientists can understand. Describe the big picture and the implications of your findings, not the study itself and the associated details. Clinical circulation research in ophthalmology is mainly concerned with the arterial side of the circulation. The primary reason may be seen in the fact that there was no method of measuring the venous pressure in the eye until recently. Therefore, the assumption was made, that the introcular venous pressure equals the intraocular pressure whose measurement is clinical routine. Twentyfive years ago, however, it was demonstrated that it is possible to measure the retinal venous pressure. Six years ago we could show that the retinal venous pressure may be higher than the intraocular pressure in about one third of glaucoma patients. Thus the assumption: “intraocular venous pressure equals introcular pressure” has to be modified: we have to discriminate between the retinal venous pressure and the choroidal venous pressure. In the study presented here we show that the retinal venous presssure goes up much higher than the intraocular pressure when the airway pressure is enhanced like in trumpet playing. It may be concluded from our results that the retinal circulation is much more influenced by enhancing the airway pressure than assumed until now. Characteristics of Retinal Blood Flow, Velocity and Vessel Diameter of eyes with Branch Retinal Vein Occlusion as revealed by Doppler Optical Coherence Tomography Flowmeter Posterboard#: A0122 Abstract Number: 5727 - A0122 AuthorBlock: Kengo Takahashi1, YS Song1, Kenji Sogawa1, Takafumi Yoshioka1, Tomofumi Tani1, Takanari Wada1, Masahiro Akiba2, Jun Sakai2, Syunsuke Nakamura2, Kana MINAMIDE2, Satoshi Ishiko1, Yasuo Yanagi1,3, Akitoshi Yoshida1 1Asahikawa Medical University, Asahikawa, HOKKAIDO, Japan; 2R&D division, Topcon Corporation, , Japan; 3Singapore National Eye Centre, , Singapore; DisclosureBlock: Kengo Takahashi, None; YS Song, None; Kenji Sogawa, None; Takafumi Yoshioka, None; Tomofumi Tani, None; Takanari Wada, None; Masahiro Akiba, Topcon, R&D division Code E (Employment), Jun Sakai, Topcon, R&D division Code E (Employment), Syunsuke Nakamura, Topcon, R&D division Code E (Employment), Kana MINAMIDE, Topcon, R&D division Code E (Employment), Satoshi Ishiko, None; Yasuo Yanagi, None; Akitoshi Yoshida, Topcon, R&D division Code P (Patent) Purpose Doppler optical coherence tomography flowmeter (DOCT flowmeter) instantaneously (< 3sec) analyses rheological properties of retinal blood vessels, including measurement of absolute retinal blood flow (RBF), blood velocity and vessel diameter. Herewith, we report the characteristics of RBF, blood velocity and vessel diameter on the occluded and the non-occluded vein in eyes with branch retinal vein occlusion (BRVO) and the vein in healthy eyes as measured by DOCT flowmeter.Methods Twenty patients with unilateral BRVO were enrolled. Using DOCT flowmeter, RBF, blood velocity, and diameter were measured from 3 veins, i.e., 1. an occlude vein, 2. a non-occluded vein in BRVO eyes and 3. a vein in the fellow eye (non-affected vein), in each patient. Paired t-test was employed to compare the parameters of DOCT flowmeter and Pearson chi-square test were used to test the association between RBF and vessel diameter. Bonferroni corrected P < 0.05 was considered statistically significant.Results Mean patient age was 65.2 ± 9.8 yrs. Mean systolic and diastolic blood pressure were 141.6 ± 19.8 mmHg and 80.1 ± 11.9 mmHg, respectively. The RBF in the occluded veins (4.7 ± 3.5 µL/min) was lower than that in the non-occluded veins (11.0 ± 5.0 µL/min) and that of the fellow eyes (8.9 ± 3.4 µL/min) (p < 0.01). There were no significant differences in the blood velocity among the three types of veins. (p > 0.1). The diameter in the occluded vein (96.1 ± 25.5 µm) was smaller than the one in the non-occluded (130.7 ± 24.1 µm) and the healthy veins (123.3 ± 15.0 µm) (p< 0.01).
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