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Mariachiara Morara, Roberto Gattegna, Nicole Balducci, Chiara Veronese, Carlo Torrazza, Maria Mottes, Maria Paola Fiorini, Antonio P. Ciardella; Multifocal Electroretinogram (mfERG) Responses In Patients With Swelling Of The Arcuate Retinal Nerve Fibre Layer (SANFL). Invest. Ophthalmol. Vis. Sci. 2012;53(14):3784.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate macular function before and after internal limiting membrane (ILM) peeling by means of mfERG related to the appearance of SANFL, an early transient appearance after ILM peeling, characterized by oedematous swelling of the arcuate retinal nerve fibre layer which disappears after a mean period of 2 months.
interventional, prospective case series. 15 eyes of 15 consecutive patients (74.17±6.44 years), undergone 25-gauge pars plana vitrectomy and ILM peeling after staining with brilliant blue G, were included. Best corrected visual acuity (BCVA), fundus infrared (IR) and autofluorescence (AF) images (Spectralis HRA+OCT, Heidelberg Engineering, Heidelberg, Germany) and mfERG (RetinaxPlus, CSO, Florence, Italy) were performed before and 1 month after surgery.
BCVA, expressed in LogMAR, significantly improved 1 month after surgery (0.52±0.36 vs 0.36±0.32, P<0.05, Mann-Whitney Test). No significant difference was found in mfERG responses before and after surgery. SANFL appearance, viewable on AF images as 3 to 5 hypofluorescent striae originating from the optic nerve head, and running between the macula and the vascular arcades, was seen in 9 patients (60%). The SANFL group was similar to no-SANFL group for all studied parameters, except for density obtained by mfERG in ring #1, which analyzes central macular 5 degrees, and ring #4, which analyzes 16-20 degrees surrounding central area (99.02±24.4 nV/deg² vs 132.54±34.22 nV/deg² and 16.40±7.40nV/deg² vs 25.53±3.79nV/deg², respectively. P <0.05 Wilcoxon test).
mfERG response is reduced 1 month after surgery in SANFL group, compared to no-SANFL group, but within the normal limits yet. The main defect is seen in the ring #1 and #4, corresponding to the area of SANFL appearance. This would indicate that the swelling of the fiber layer also influences outer retinal layers responses to mfERG stimuli. Further studies are needed to assess if defects are permanent or disappear together with SANFL and if the electrophysiological defects are visible also when ganglion cells are stimulated.
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