Retinal non-perfusion in diabetic retinopathy.

Diabetic retinopathy is a major cause of vision loss worldwide and areas of retinal non-perfusion (RNP) are a key pathologic feature of the vascular component of diabetic retinopathy. While there is a need for a more complete understanding of the natural history of RNP development and progression, overall, increasing RNP has been closely linked with worsening DR severity. Both traditional and novel approaches to quantitative image assessment are being explored to advance our understanding of the vascular, physiologic and functional changes associated with progressive RNP. Retinal ischemia secondary to RNP leads to tissue hypoxia and changes in the expression of a host of signalling molecules. Current anti-vascular endothelial growth factor and steroid pharmaceutical agents appear to be unable to reperuse areas of RNP, but may be able to slow the progressive longitudinal accumulation of RNP with regular retreatments. There remains a tremendous unmet need for pharmacotherapies that can slow RNP progression and ultimately reperfuse areas of the non-perfused retina. Towards this end, novel targets including the semaphorin family are being investigated.