Retinal oxygenation response and retinopathy.

Oxygen supply and demand of the retina, one of the most metabolically active tissues in the body, must be dynamically balanced to insure the health of the tissue. The integrity of such active regulation can be assessed by measuring retinal oxygenation response (ROR) to a hyperoxic provocation. Over the last decade, we have developed an MRI-based technique to measure ROR as a change in vitreal oxygen level from room air breathing to a new hyperoxic condition (DeltaPO2). This review summarizes progress to-date in the development and application of MRI ROR measures in retinopathy with emphasis on the spatial and temporal association of subnormal ROR and non-proliferative and proliferative retinopathy, as well as examining the usefulness of ROR as a surrogate marker of drug treatment efficacy. Recent adaptation of the MRI technique has made measurement of human ROR routine raising the likelihood of clinical trials.