[Hemodynamics of prepapillary vascular loop in hemi-central retinal vein occlusion]

It has been shown, by indocyanine green (ICG) videoangiography, that the prepapillary vascular loops in chronic central retinal vein occlusion (CRVO) serve as an anastomosis between the retina and the choroidal venous systems. Similar vascular loops may develop in hemi-central retinal vein occlusion (hemi-CRVO).

I performed indocyanine green and fluorescein angiography using a scanning laser ophthalmoscope in 8 eyes of 8 patients with hemi-CRVO to evaluate the angioarchitecture and hemodynamics of the retinochoroidal circulation. All eyes had a prepapillary vascular loop and were identified as ischemic. The patients' ages ranged from 28 to 77 years (mean, 57 years). The interval between onset of hemi-CRVO and angiography ranged from 2 to 42 months (mean, 13 months). Scattered laser photocoagulation had been applied to the affected area in all 8 eyes and vitreous surgery in one eye.

Delayed dye flow in the affected retinal veins was present in all 8 eyes. The blood in the affected retinal veins drained through the prepapillary vascular loop into the branch or trunk of the intact central retinal vein. No anastomoses were seen between the vascular loop and the choroidal veins. The prepapillary vascular loop became more dilated during follow-up in one eye.

The prepapillary vascular loop in hemi-CRVO served as a collateral from the affected into intact retinal veins and not into the choroidal venous system.