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Anastasia Siegel, Michael Haustein, Naim Terai, Lutz Pillunat, Richard Stodtmeister, Eberhard Spoerl; Autoregulation of retinal vessel diameter in diabetic macular edema is not altered by intravitreal ranibizumab. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2372. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
In patients with diabetic macular edema the autoregulatory response of retinal vessel diameter before and three times after intravitreal injections of ranibizumab was investigated
30 eyes of 30 patients aged 60±11years (mean ± SD) (M/F: 14/16) participated in this prospective study. Inclusion criterion: clinically significant diabetic macular edema. Treatment: three intravitreal injections of ranibizumab at intervals of four weeks. Examination time points: before first (TP1), second (TP2), third (TP3) injection and three months after the first one (TP4). Parameters: Systemic blood pressure, retinal vessel diameter by still images: central retinal artery (CRAE) and vein equivalent (CRVE) (Visualis, Imedos, Germany) and change in vessel diameter in response to flicker stimulation (Dynamic Vessel Analysis, Imedos, Germany): 50s baseline recording followed by online measurement during 20s flicker stimulation (push-pull interruption of fundus illumination) and 80s online measurement in an arteriolar and venolar vessel segment. Three recording cycles were averaged. Statistics: Analysis of variance (ANOVA) for repeated measurements or Friedman-test, Student t-test for paired samples, Bonferroni-Holm correction (SPSS 17). Target figures: Diameter change of retinal arterioles and venoles. Level of significance: alpha=5%.
Systolic blood pressure BP: 160±18(mmHg,arith.mean±s), diastolic BP: 86±11. No significant change TP1-TP4 (p=0.10). CRAE in µm: TP1: 182±23, TP2: 172±22, TP3: 174±27, TP4: 171±22 (ANOVA: p=0.02). CRVE TP1: 216±25, TP2: 213±25, TP3: 215±24, TP4: 211±24 (ANOVA: p=0.12). Flicker response, dilation,%: Arterioles TP1: -4.80,1.20,5.7; venoles TP1: -0.90,2.65,7.2. No significant change TP1-TP4 (Friedman-test): arterioles: p=0.13, venoles: p=0.15. The differences of the flicker response TP2-TP1, TP3-TP1, TP4-TP1 didn’t differ significantly from zero (p>0.10).
The CRAE may be significantly lower from TP2-TP4 compared to TP1 before the first injection of ranibizumab. This observation is consistent with earlier findings in the literature. The CRVE, however, doesn’t show a significant change. The median flicker response in arterioles and venoles is remarkably lower compared to healthy subjects and shows no significant change after ranibizumab treatment.
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