Purpose: To evaluate patients who had undergone radial optic neurotomy for central retinal vein occlusion for the presence of retinal choroidal collateral circulation and to correlate these collaterals with changes in macular thickness during follow-up. Radial optic neurotomy is designed to release proposed pressure within the scleral canal.
Methods: Retrospective review of patients undergoing radial optic neurotomy. The patients had a baseline examination including ophthalmoscopy, fluorescein angiography, and optical coherence tomography. At an interval follow-up at approximately 3 months the patients were reevaluated with ophthalmoscopy, optical coherence tomography, and indocyanine green angiography.
Results: There were 6 patients, and the mean age was 68.3 years. The mean time from onset of the central retinal vein occlusion to the radial optic neurotomy was 2.3 months. One patient had no collateral vessels, three patients had significant collaterals, and two patients had moderate-caliber collaterals. The mean central macular thickness preoperatively was 1,021 microm and the mean central macular thickness postoperatively was 733 microm. The change in macular thickness was highly correlated with the degree of development of collaterals from the retinal to the choroidal circulation (P = 0.008, Spearman's rho = 0.93).
Conclusion: Although all patients had a radial optic neurotomy a significant determinant in reduction of macular edema was the presence of retinal-choroidal collateral circulation. This suggests that there may be additional mechanisms, other than simple release of alleged pressure in the scleral canal, for any observed effects from radial optic neurotomy.