Formation of retinochoroidal collaterals in central retinal vein occlusion.

PURPOSE: To demonstrate the drainage routes that compensate the venous congestion in central retinal vein occlusion.
METHODS: Indocyanine green angiography was performed in 13 eyes of 13 patients with central retinal vein occlusion at the involutional stage using a scanning laser ophthalmoscope. The interval between onset of central retinal vein occlusion and indocyanine green angiography ranged from 1.0 to 9.3 years (mean, 3.6 years). Panoramic indocyanine green angiograms that covered the entire choroidal vasculature were produced by composing regional angiograms.
RESULTS: Retinochoroidal collateral routes were found in 10 eyes that had papillary vascular loops. They were not observed in three eyes that did not have the vascular loops. Papillary vascular loops served as the collaterals to connect retinal veins and choroidal veins. The blood in the retinal veins was drained through the papillary vascular loops into the choroidal veins. These choroidal veins were selectively dilated and acted as drainage routes to the vortex veins. Nasal vortex veins served as extraocular exits of the drainage routes in all 10 eyes, and temporal vortex veins served as extraocular exits of the drainage routes in three of the 10 eyes.
CONCLUSIONS: In central retinal vein occlusion with papillary loops, blood in the retinal veins ultimately drained into the vortex veins through the retinochoroidal collaterals.