Chroidal anastomoses after radial optic neurotomy

José Garcia–Arumi, V. Martinez, A. Boixadera (Barcelona)

Purpose: To assess the visual outcome, the incidence of chorioretinal anastomosis and the decrease in foveal thickness measured by Optical Coherence Tomography (OCT) of Radial Optic Neurotomy (RON) with one compared to three nasal neurotomies in patients with Central Retinal Vein Occlusion (CRVO).
Methods: Prospective, interventional, comparative study including 37 patients (37 eyes) with CRVO of less than 12 months from onset, and preoperative visual acuity below 20/125. Pars Plana Vitrectomy, Posterior Hyaloid Dissection and RON using a microvitreoretinal blade, was done. Three nasal RON were performed in an attempt to increase neural ring decompression and promote chorioretinal anastomosis in 23 patients, while 14 patients underwent a single nasal RON. Best corrected visual acuity and Optical Coherence Tomography (OCT) were registered preoperatively and at 1, 3 and 6 months.
Results: No patient had a decrease in VA postoperatively. Clearing of hemorrhages and decrease in macular edema as measured by OCT was observed in all of them. 43% of patients in the single-RON group gained > 2 lines versus 10.5% after triple-RON, p = 0.04. Mean decrease of macular thickness on OCT was 39 % with one neurotomy versus 48% with three. New chorioretinal anastomoses appeared in the location of the neurotomy in 43% of cases after single-RON versus 48 % after triple-RON.
Conclusion: Surgical decompression of CRVO with RON seems to improve or at least stabilize the prognosis of patients with severe CRVO. We presume that improvement occurs due to the optic nerve head decompression, the vitrectomy and posterior hyaloid dissection itself, as well as by the newly formed retinochoroidal shunts (anastomoses) that drain the retinal circulation to the choroid and accelerate the resolution of the retinal edema.
Single-RON appears to be more effective, despite lower decrease in macular thickness on OCT and fewer newly formed chorioretinal anastomoses, compared to the triple-RON procedure.
A randomized, controlled trial, and a larger number of patients are needed to prove the efficacy and safety of this procedure and definitively demonstrate the optimal number of neurotomies.
Intravitreal triamcinolone acetonide as treatment of macular edema in CRVO has been recently reported, and may offer other alternative treatment in these patients, employed alone or combined with surgery. We describe our preliminary results.


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