Microvascular injection studies in rubeosis iridis and neovascular glaucoma

Microvascular silicone injection, tissue clearing, and histologic examination were used to demonstrate the origin, distribution, and interconnections of newly formed iris and chamber angle blood vessels in four eyes with rubeosis iridis and neovascular glaucoma associated with diabetic retinopathy and central retinal vessel occlusion. The newly formed iris vessels that formed either a tight, evenly distributed (diabetic) or loose, irregularly distributed (central vessel occlusion) network in the iris originated from the normal iris arteries that were branches of either the major arterial circle or of the perforating branches of the anterior ciliary arteries, and drained into the normal iris and ciliary body veins and occasionally into the paralimbal episcleral veins. These newly formed iris vessels appeared to shunt intravascular fluid from arteries to veins. The newly formed anterior chamber angle vessels that formed tufts and arcades at the trabecular meshwork also originated from the roots of the iris arteries and the ciliary body arteries and connected with the peripheral neovascular iris network. In addition, the circumferentially running angle vessels that coursed within the trabecular meshwork branched into and coursed within a fibrosed Schlemm's canal and into two of its intrascleral collector channels. No open communication between these newly formed vessels and the Schlemm's canal-aqueous outflow system was seen.