Retinal to Choroidal Collaterals Following Radial Optic Neurotomy as a Mechanism for Decreasing Macular Edema in Patients With Central Retinal Vein Occlusion

Abstract

Abstract: : Purpose: Central retinal vein occlusion (CRVO) is a common cause of vision loss. The formation of venous collaterals, either through the natural history or induced via treatment may aid in the resolution of macular edema and may impact the visual acuity. The aim of this study was to evaluate the role of radial optic neurotomy (RON) in creating retinal choroidal collaterals and reducing macular thickness. Methods: This is a prospective case series. A consecutive series of eight patients who were treated with radial optic neurotomy for CRVO were enrolled in the study. Patients were followed with indocyanine green (ICG) angiography to identify the development of retinal-choroidal collaterals. Optical coherence tomography (OCT) was used to measure retinal thickness. Results: Retinal to choroidal collaterals were identified with ICG angiography in 8 patients. Three patients had large collaterals. Two patients had a large number of smaller of collaterals. Three patients had minimal collaterals. Some patients had a large number of smaller collaterals prior to the development of a dominant large collateral. The mean macular thickness preoperatively was 1021 microns. Postoperatively it was 646 microns (p=0.02). Conclusions: Radial optic neurotomy may aid in resolution of macular edema by the formation of collaterals at the optic disc margin. Blood flow within these collaterals can be traced by ICG angiography from the retinal to the choroidal circulation. The presumed mechanism for RON in CRVO is a mechanical decompression of the retinal veins related to the physical release of the scleral ring. Our findings support a novel hypothesis that anastomotic connections between the retina and choroid may contribute to resolution of macular edema from CRVO. Further research is warranted to evaluate this technique and its clinical relevance.

Keywords: vascular occlusion/vascular occlusive disease • retina