Study On Effects Of Internal Limiting Membrane Peeling On Visual Function In Idiopathic Macular Hole Surgery

Objective:To determine whether there are functional changes in the inner retina after internal limiting membrane peeling in idiopathic macular hole (IMH) surgery. To assess the safety and efficacy of macular hole surgery and its indication.Method:The photopic negative respone (PhNR) is a useful clinic test to detect early impairment of ganglion cells and optic nerve. IMH eyes with a history shorter than 6 months were selected consecutively. Eyes in macular hole stageⅢorⅣunderwent vitrectomy. non-dye internal limiting membrane peeling, air tamponade and face-down posture. In addition to the routine ophthalmic examinations, phtopic ERGs were recoreded in all eyes, before and 3 months after surgery. Phtopic ERGs were elicited by red Ganzfeld flashes on a rod-suppressing blue background. The amplitudes of the PhNR,α- andβ-waves of photopic ERGs before and after surgery were compared. PhNR were also recorded in eyes in macular hole stageⅡ, which underwent vitrectomy only, before and after surgery, and compared in the same method. Follow-up time is 6～12 months. Observe effects of internal limiting membrane peeling on visual function and effects of vitrectomy on visual function. The statistical software SPSS 13.0 was used to analyze the date. Best-corrected visual acuity before and after surgery were compare by Wilcoxon Ranks Test-related samples. Amplitudes ofα,βand PhNR before and after surgery were compared by Wilcoxon Signed Ranks Test. P<0.05 was considered to be statistically significant.Result: 32 consecutive eyes in macular hole stageⅢorⅣwere admitted in this trial, the average diameter of macular hole was 375.6μm(352μm-445μm),30 eyes (30/32,93.6%) achieved anatomic closure, best-corrected visual acuity improved by 0.24 (pre-operation 0.10±0.05, post-operation 0.34±0.17). The amplitude of the PhNR was significantly reduced by 12.1μv after surgery (Pre-operation 33.6±3.9μv, Post-operation 21.5±6.5p.v, P＜0.05), whereas the amplitude of the photopicα-andβ-waves were not significantly altered(P>0.05).40% of the patients had peculiar phenomena during short term follow-up:image flickers when they closed their eyes, movement when they observe small visual marks. In the corresponding period,26 eyes in macular hole stageⅡwere admitted in Non-internal limiting membrane peeling group, the average diameter of macular hole was 258.4μm(230μm～292μm),25 eyes (25/26,96.2%) achieved anatomic closure. Best-corrected visual acuity improved by 0.31 (pre-operation 0.33±0.10, post-operation 0.64±0.19). The mean amplitude of the PhNR was slightly decreased after surgery, but the degree of reduction was only1.0μv (P>0.05), the amplitude of the photopicα- andβ-waves were not significantly altered (P>0.05)Conclusion: Internal limiting membrane peeling is an efficient procedure to improve closure rate and visual acuity in IMH in stageⅢorⅣ. There is some functional impairment in the inner retina after internal limiting membrane peeling. However, comparing to its benefits, the impairment is small. For IMH in stageⅡ, high closure rate and visual quality can be achieved without internal limiting membrane peeling.