Purpose:
To determine the effect of intravitreal bevacizumab on oxygen saturation within primary and secondary retinal vessels.
Methods:
Retrospective review. The Oxymap T1, an investigational device, was used to quantitatively measure oxygenation in retinal vessels pre-injection and one to two weeks post-injection of intravitreal bevacizumab. Blood changes its color and optical density due to its level of oxygenated hemoglobin. The Oxymap Analyzer captures two simultaneous images at 570nm (oxygen insensitive) and 600nm (oxygen sensitive). The ratio of these two opitcal densities at points along a vessel is linearly related to its oxygen saturation. The software superimposes a colored oxygenation map on all 50° images. Vessel segments can be selected for detailed numerical analyses. All primary and secondary vessels were selected to generate the mean arterial and venous oxygen saturation, respectively.
Results:
This study included 13 eyes of 13 patients receiving intravitreal bevacizumab for macular edema. Pre-injection vessel oxygenation was compared directly to post-injection oxygenation. The mean age was 59.92 ± 12.41 years, 61.5 % were male, 53.8% were diabetic, 76.9% were hypertensive, and 7.7% had glaucoma. Mean pre-injection arterial and venous blood oxygenation in primary and secondary vessels was 102.19% ± 4.84% and 65.56% ± 7.22%, respectively, and mean post-injection arterial and venous blood oxygenation was 100.99% ± 4.84% and 64.78% ± 10.47%, respectively. Paired t-tests did not reveal a statistically significant difference between pre- and post-injection oxygenation (p = 0.697 for arterial oxygenation; p = 0.307 for venous oxygenation).
Conclusions:
Based on the Oxymap data, intravitreal bevacizumab does not appear to adversely affect retinal arterial or venous oxygenation in primary and secondary vessels in patients receiving this treatment for macular edema.
Keywords: image processing • oxygen • blood supply