Retinal vascular oximetry during ranibizumab treatment of central retinal vein occlusion

Purpose To investigate the effect of intravitreal injections of the vascular endothelial growth factor inhibitor ranibizumab on retinal oxygenation in patients with central retinal vein occlusion (CRVO). Methods Retinal oxygen saturation in patients with CRVO was analysed using the Oxymap Retinal Oximeter P3, before and during 6 months of treatment with intravitreal injections of ranibizumab. Results At presentation, retinal venous oxygen saturation was lower in eyes with CRVO than in the healthy fellow eyes (32 +/- 13% vs 59 +/- 10%, respectively, p=0.001) whereas retinal arterial saturation was higher in eyes with CRVO than in the fellow eyes (95%+/- 8% and 91%+/- 3%, p=0.04). Mean visual acuity increased from 51 +/- 24 letters ETDRS at baseline to 66 +/- 24 and 69 +/- 20 letters ETRDS, respectively, at 3 months and 6 months treatment (mean +/- SD, p<0.0001, repeated measures analysis of variance) and central retinal thickness was reduced from 697 +/- 139 mu m to 368 +/- 113 mm and 340 +/- 96 mu m, respectively, from baseline to 3 months and 6 months treatment (p<0.0001). Venous saturation increased during treatment (from 35.5%+/- 13.8% at baseline to 43.1%+/- 10.8% and 43.5%+/- 13.7% after 3 months and 6 months treatment, respectively, p=0.012), while no significant change was found in arterial saturation (p=0.24). Conclusions Retinal venous oxygen saturation was markedly reduced in untreated CRVO and was roughly halfway normalised during intravitreal ranibizumab treatment. Retinal artery oxygen saturation was not reduced in CRVO.