Potentially reversible effect of niacin therapy on edema from retinal vein occlusion.

Niacin may transiently dilate potential collateral vessels via an nitric oxide-dependent mechanism, facilitating the maintenance of the vessel's lumen diameter by hydrostatic blood pressure.

With the establishment of collaterals to bypass vascular obstruction, some retinal vein occlusions (RVOs) may resolve spontaneously.

Niacin may also have an added cardiovascular benefit for patients typically diagnosed with RVO.