Characteristics of visual field defects by scanning laser ophthalmoscope microperimetry after radial optic neurotomy for central retinal vein occlusion

Purpose: To evaluate visual field defects after radial optic neurotomy (RON) for the treatment of central retinal vein occlusion (CRVO) by using scanning laser ophthalmoscope microperimetry. Methods: Thirteen eyes of 13 patients with severe vision loss (≤20/200) from CRVO who underwent pars plana vitrectomy and RON had postoperative Goldmann kinetic perimetry, scanning laser ophthalmoscope microperimetry, and fluorescein angiographic evaluation. Results: After a mean follow-up of 8 months, 6 of the 13 patients had visual improvement by ≥2 lines. Eight patients developed an anastomosis at the radial cut. Postoperatively, sectorial visual field loss arising from the optic head was found by Goldmann perimetry in six patients, and a thin nerve fiber bundle defect was found in three patients. Four patients had no detectable visual field defect shown by Goldmann perimetry, but microperimetry demonstrated an absolute nerve fiber bundle defect arising from the radial cut at the optic disk for three of these patients. Conclusion: Visual field loss after RON for the treatment of CRVO is a frequent complication. The etiology of this visual loss appears to be a combination of mechanical trauma to the nerve fiber layers and ischemia of the optic disk circulation.