DETRIMENTAL EFFECTS OF ACTIVE INTERNAL LIMITING MEMBRANE PEELING DURING EPIRETINAL MEMBRANE SURGERY Microperimetric Analysis

Introduction: The aim of the study was to assess the microperimetric consequences of active internal limiting membrane (ILM) peeling during idiopathic epimacular membrane (IEMM) surgery. Materials and Methods: This retrospective monocentric study included 32 eyes of 31 consecutive patients who underwent IEMM surgery. Internal limiting membrane integrity was assessed by ILM Blue staining after IEMM removal: peeling was spontaneous (Group S) or active (Group A). Preprocedure and postprocedure (1 and 6 months) examinations were performed using visual acuity determination, spectral domain optical coherence tomography and microperimetry. Results: Twenty-two eyes had an "active ILM peeling" and 10 a "spontaneous ILM peeling." Both groups had comparable and significant improvements in visual acuity 6 months after surgery (+ 1.82 lines [+ 9 letters] [Group A] and + 1.51 lines [+ 8 letters] [Group S], P < 0.01) associated with a significant reduction in optical coherence tomography central thickness (-99.9 mu m [Group A], P < 0.01 and -62.2 mu m [Group S], P = 0.05). Six months after surgery, the microperimetry showed more numerous and deeper microscotomas in the Group A than in the Group S (change in the number of microscotomas: 2.09 vs. -0.10, P = 0.06; change in deficit severity score: 13.18 dB vs. -2 dB, P < 0.01 for Group A and S, respectively). The number of microscotomas and also severity were increased in 63.6% of Group A patients and in only 20% of Group S patients. Microscotomas were most frequently located in IEMM and/or ILM areas. Discussion: Internal limiting membrane peeling has progressively become generalized in IEMM surgery to reduce recurrences. This additional procedure does not change the postoperative visual acuity but increases the development of deeper microscotomas. The real impact on the quality of vision remains unclear. Conclusion: Active ILM peeling in IEMM surgery may be responsible for visual impairment related to its microtraumatic effects.