Collateral circulation in hemicentral retinal vein occlusion

The perchance occurrence of a hemicentral retinal vein occlusion in an eye with a lightly pigmented fundus allowed us the opportunity to observe the development and flow dynamics of collateral circulation. We are able to demonstrate an optic disc collateral draining into a choroidal vein, a finding which to our knowledge had previously only been documented histologically. The collateral circulation developed slowly over many months and was not rapid enough to prevent chronic microcystic macular changes.