Abstract
Abstract: :
Purpose: Central retinal vein occlusion (CRVO) is caused by venous thrombosis at and posterior to the level of lamina cribrosa in the optic nerve and can cause significant vision loss. There is no effective treatment for ischemic CRVO. Recent reports showed that radial optic neurotomy (RON), a procedure with an incision on the optic disk to relax the scleral ring and cirbriform plate, can decompress the central retinal vein leading to reperfusion of retina, and thus improve patient’s vision. To investigate whether this procedure can change the ocular blood flow, color Doppler imaging (CDI)was used to measure the flow before and after the RON procedure. Methods: A patient with ischemic CRVO was enrolled for this study. Patient’s visual acuity, fundus exam, fluorescein angiography (FA), and optical coherence tomography (OCT) were followed. CDI was preformed to measure the blood flow and resistance of ophthalmic artery (OA), central retinal artery (CRA), and temporal posterior ciliary artery (TPCA) before and after the RON procedure. Results: The patient’s visual acuity was count finger before surgery with typical ischemic CRVO appearance including dilated and torturous vein, diffuse intra–retinal hemorrhage, severe macular edema and optic nerve edema. Two weeks postop, patient’s vision improved to 20/70 with foveal thickness improvement from preop more than 600 um to 250 um on OCT. Six weeks later, vision was 20/40 with foveal thickness of 150 um. Compared to the fellow normal eye, OA flow volume was significantly increased; whereas CRA and TPCA flow volume were significantly decreased in the CRVO eye at both preop and postop time. In the CRVO eye, OA flow volume showed more than one fold increase than the fellow eye at 6 weeks postop, whereas OA flow resistance showed significant decrease within this period. CRA flow did not show consistent postop change, and TPCA showed a decrease in flow volume 6 weeks after surgery. Conclusions: Our results show that OA blood flow volume significantly increases and its resistance significantly decreases following radial optic neurotomy. Also TPCA flow volume decreases after surgery. It is hypothesized that a local regulation system exists in the eye which releases signal and elevates OA flow when CRVO occurs to compensate retinal ischemia. It remains to be determined whether these blood flow changes are due to natural course of the disease or the surgical intervention. A larger serious of patients with longer follow up time is desirable for this study.
Keywords: optic disc • vascular occlusion/vascular occlusive disease • vitreoretinal surgery