Comparison of changes of multifocal electroretinography (mfERG) after subretinal neovascular membrane excision with and without autologous retinal pigment epithelium transplantation

Abstract

Abstract: : Purpose: Different examination methods are used to evaluate macular functions after interventional therapies of retinal disorders. The aim of this study was to compare the macular mfERG changes after subretinal neovascular membrane excision with and without autologous retinal pigment epithelium (RPE) transplantation in patients with advanced AMD. Methods: mfERG was recorded in 51 patients, who underwent subretinal neovascular membrane excision with autologous RPE transplantation (group I) and in 15 of the control group (only membrane excision, group II) up to 12 months. Measurements were recorded preoperatively, one month postoperatively and at 3 months intervals thereafter. We used the Retiscan System (version 3.1, Roland Consult, Wiesbaden, Germany) with DTL conjunctival electrodes. The stimulus arrays of 103 flickering hexagons were presented on a 21" monitor. The quality of the records was controlled by the real–time monitoring. Results: The preoperative mean response density of the b–wave in the macular region was 90.6 nV/deg² in the transplanted group and 97.4 nV/deg² in the control group. The maximal increase of mfERG values (mean: 104.8 nV/deg ²) was observed three month after surgery in the transplanted group. The average of response density in macula region for b–wave in the 1^st, 3rd, 6^th, 9^th, and 12^th months was 99.9, 104.8, 84.1, 85.9, 91,0 nV/deg² in group I and 93.4, 74.7, 75.4, 80.3, 69.6 nV/deg² in the control group, respectively. The difference between group I and II was statistically significant (p=0.0474). Similar findings were also observed in follow–up of the a–wave for both groups (72.3, 79.1, 81.0, 74.2, 66.1, 71.1 nV/deg² in group I and 78.8, 63.5, 75.7, 72.5, 59.4, 65.8 nV/deg² in group II preoperative, in the 1^st, 3rd, 6^th, 9^th, and 12^th months, respectively). The implicit time for a– and b–wave was prolonged in both groups compared to age– matched healthy subjects. Conclusions: Changes in both a– and b–waves in mfERG after surgical membrane excision and autologous RPE transplantation presents a positive development of the local potentials compared with membrane excision alone in patients with AMD. Since the mfERG (kernel first order) is mostly elicited in outer retinal layers, this suggests a positive effect of transplanted RPE cells in restoring or stabilization of retinal functions.

Keywords: age–related macular degeneration • electroretinography: clinical • retinal pigment epithelium