Evaluation of radial optic neurotomy for central retinal vein occlusion by indocyanine green videoangiography and image analysis

PURPOSE: To evaluate the effects of radial optic neurotomy (RON) on retinal circulation in patients with central retinal vein occlusion (CRVO) by indocyanine green (ICG) videoangiography and a computer-assisted image analysis. DESIGN: An interventional case series. METHODS: RON was performed in 15 eyes of 15 patients with CRVO. Within 72 hours before the surgery and at 3 months after the surgery, ICG videoangiography was performed with a scanning laser ophthalmoscope, and the images were transferred to a computer. Two measurement points were selected, one on a main retinal artery close to the optic disk and the other on the corresponding retinal vein. At each point, fluorescence intensities were serially measured, and dye dilution curves were obtained. Retinal circulation times (DeltaT(50)) before and after the surgery were calculated. RESULTS: Mean preoperative DeltaT(50) was 6.46 +/- 1.36 seconds, and mean postoperative DeltaT(50) was 6.80 +/- 2.50 seconds. In 8 of 15 eyes, T(50) decreased by 6.8% to 29.6% after the surgery. In the seven eyes that developed chorioretinal anastomosis (CRA) at the site of RON, DeltaT(50) decreased after the surgery. In contrast, DeltaT(50) decreased postoperatively in only one of the eight eyes without CRA. Best-corrected visual acuity improved significantly after the surgery in the group of eyes with improvement in DeltaT(50), but not in the group of eyes without improvement in DeltaT(50). CONCLUSIONS: Some degree of retinal circulation improvement occurred in approximately half of these eyes, which appears to be correlated with the development of CRA.