Nonarteritic anterior ischemic optic neuropathy and 'visual field defects' following vitrectomy: Could they be related?

Background: Visual field defects after uncomplicated vitrectomy have been reported but poorly explained. We describe two cases of nonarteritic anterior ischemic optic neuropathy (NAION) observed following vitrectomy. We also reviewed the literature for cases of post-vitrectomy visual field defects for evidence of optic nerve damage. Methods: Two patients developed optic disc edema and features of an optic neuropathy after uncomplicated vitrectomy for macular hole and epiretinal membrane. A systematic literature search was conducted to obtain prior reports of visual field defects or ischemic optic neuropathy following vitrectomy. Additional studies were identified from the bibliographies of the retrieved articles. Results: The incidence of visual field defects following vitrectomy has varied from 1-71% across all studies. Overall, we found 160 (14.5%) cases of unexplained visual field defects following vitrectomy out of 1,104 patients. Of these, 31 eyes (19.4%) have shown some sign of optic nerve damage following vitrectomy, including pallor in 29 eyes, relative afferent pupillary defect in eight eyes, and intrapapillary hemorrhage in two eyes. Conclusions: NAION may develop following vitrectomy. "Visual field defects" following vitrectomy are common and many of the involved eyes demonstrate evidence of optic nerve damage, some of which may have represented NAION.