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Lisa Ramm, Dirk Sandner, Damian Burkert, Richard P Stodtmeister, Naim Terai, Lutz E Pillunat; The effect of anti-VEGF therapy on oxygen saturation and diameters of retinal vessels in patients with diabetic macular edema. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1893. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Disturbances of microcirculation and ischemia are causes of diabetic retinopathy. A vision threatening complication is a macular edema whose treatment of choice is the intravitreal anti-VEGF therapy. In the present study the effect of VEGF inhibitors on retinal circulation in diabetes mellitus was investigated.
16 patients with diabetic macular edema (64.3 ± 8.6 years) were included. Each subject received 3 anti-VEGF injections (10 Aflibercept/6 Ranibizumab, 1-month interval). Prior to each injection and after the third treatment, vessel diameters and oxygen saturation of retinal vessels were measured (Retinal Vessel Analyzer, Imedos Systems UG). Central retinal artery (CRAE) and vein (CRVE) equivalents were calculated from diameter measurements in peripapillary vessels. The oxygen saturation was investigated using a two-wavelengths technique. The central retinal thickness was determined by OCT. Blood pressure and HbA1C were assessed. The results of the first and the fourth examination (difference defined as change) were compared (Wilcoxon test). Associations were examined using Pearson correlation analysis.
The change in venous saturation (r = 0.594, p = 0.025) and in arterio-venous difference of oxygen saturation (r = -0.603, p = 0.05) was correlated to the initial retinal thickness. An association between the change in arterio-venous saturation difference and the retinal thickness reduction was assessable (r = -0.751, p = 0.02). In comparison to the results before therapy, the venous oxygen saturation increased (62.3 ± 7.2 vs. 66.7 ± 12.1 %) not significantly. Also, a trend to a rise in CRAE (179.2 ± 33.6 vs. 189.9 ± 43.9, p = 0.237) and CRVE (222.4 ± 29.5 vs. 230.4 ± 18.4, p = 0.043) was shown. The increase in CRAE correlated significantly to mean arterial pressure (r = 0.596, p = 0.032). The retinal thickness decreased during therapy (401.3 vs. 343.4 μm, p = 0.047).
A possible reason for the increase in vessel diameters and venous oxygen saturation during therapy might be a reduction of vascular resistance in the process of macular edema remission. In accordance, the arterio-venous saturation difference as a marker for oxygen extraction decreased with reduction of retinal thickness. This might indicate a rise in retinal perfusion during therapy. Also, a higher cellular oxygen demand in case of diabetic macular edema is conceivable.
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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