Intraocular oxygen gradients measured in advanced proliferative diabetic retinopathy

Am J Ophthalmol. 2011;152(3):406-412

Significant intraocular oxygen gradients in proliferative diabetic retinopathy were found in a study to measure oxygen levels at sites in the vitreous and at the inner retinal surface.

The findings support the hypothesis that VEGF spurs the development of neovascular complexes in the posterior retina that are "richly perfused but nonetheless fail to stem hypoxia in the mid-vitreous."

"Upregulation of vitreous VEGF may be a consequence of retinal hypoxia at unidentified sites or of chronic inflammatory processes in advanced proliferative diabetic retinopathy," the study authors said.

Intraocular oxygen tensions were measured using an OxyLab pO2 sensor (Oxford Optronix) in fast mode of one measurement per second. The study also measured vitreous and plasma concentrations of 42 cytokines and their correlation with intraocular oxygen tension.

Subjects included a 14-patient control group and 14 patients with advanced proliferative diabetic retinopathy who had, despite previous panretinal photocoagulation, developed tractional retinal detachments.

Mean oxygen tension in the mid-vitreous was 46% lower than in the control group (P = .017). The mean preretinal oxygen tension at the posterior pole was 37% higher than in controls (P = .039).