Inner retinal optic neuropathy: vitreomacular surgery-associated disruption of the inner retina.

PURPOSE: Macular pucker (MP) and macular hole (MH) are vitreomaculopathies treated by vitrectomy and membrane peel. The complication of postoperative central scotoma can be associated with significant reduction in visual acuity (VA). We seek to determine whether retinal nerve fiber layer (RNFL) disruption is the pathophysiologic basis of this defect. Mitigating clinical circumstances also were sought.

METHODS: Eleven eyes from 10 pseudophakic patients who had undergone vitrectomy with peeling for either MH or MP were studied with clinical measures, including optical coherence tomography (OCT). Membrane specimens were evaluated by immunohistochemistry for neurofilament, a marker for the inner retina. Ten eyes from 10 pseudophakic patients who underwent repeat surgery for persistent or recurrent pathology were evaluated to determine the relationship between the timing of reoperation and clinical outcome.

RESULTS: Cases with a postoperative central scotoma (N=4) had worse VA (~20/600) compared to those without (N=7, ~20/30, P=0.01). Eyes with a central scotoma had significantly reduced RNFL thickness in the temporal quadrant (53.67 vs. 72.33 μm, P=0.05) by OCT. A central scotoma was associated with more disruption of the inner retina on immunohistochemistry (P=0.03). In patients with persistent or recurrent pathology, waiting six months before reoperation resulted in better functional outcomes (P=0.03).

CONCLUSIONS: Central scotomata and poor VA were associated with disruption of the RNFL during membrane peeling. Affected patients have RNFL thinning and signs of optic neuropathy, for which we propose the term inner retinal optic neuropathy (IRON). In patients requiring reoperation, waiting six months between surgeries may reduce the risk of IRON.