Abstract
Purpose: :
Removal of an epiretinal membrane (ERM) and the internal limiting membrane (ILM) via pars plana vitrectomy (PPV) is a standard procedure. The course to restore a stable macular anatomy after surgery is unknown. The aim of this study was to determine the changes of the central retinal thickness (CRT), the central retinal volume (CRV) and the foveal contour by means of spectral domain OCT (SD-OCT) and the best-corrected visual acuity (BCVA).
Methods: :
Prospective interventional case series. 55 eyes of 55 patients underwent PPV with membrane peeling for ERM removal between 04/2008 and 06/2009. Mean follow-up was 124 days (range 11 to 342 days, median 106 days). Ophthalmic evaluations included BCVA and SD-OCT (Spectralis, Heidelberg Engineering) preoperatively and 3 to 6 months postoperatively. Additional OCT measurements were done during the hospitalization period and 2 weeks postoperatively. We evaluated the OCT parameters CRT, CRV and the foveal contour as well as the change in BCVA over time.
Results: :
The ILM was removed in 44/55 eyes (80%). Mean BCVA increased from 0.55 to 0.38 (logMAR, p<0.001, paired t-test) and mean CRT decreased from 511µm (range 267µm to 800µm) to 393µm (range 180µm to 540µm, p<0.001, paired t-test) at the end of follow-up. CRV decreased from 3.24mm3 (range 2.30mm3 to 4.18mm3) to 2.65mm3 (range 2.21mm3 to 3.22mm3, p<0.001, paired t-test). There is a significant positive correlation between high preoperative CRT and gain in BCVA (ANOVA, p=0.033). An almost normal foveal depression could only be restored in 7 of 55 eyes. 2 patients had to undergo additional surgical intervention due to retinal detachment.
Conclusions: :
Despite reliable removal of the ERM and in most cases of the ILM increase in BCVA is rather moderate and restoration of a normal foveal depression is rare. Whereas the decrease in CRT and CRV was expected, the positive correlation between high preoperative CRT and gain in BCVA is surprising. We therefore suggest that even patients with very thick epiretinal membranes, CRT > 700µm and structural macular changes should undergo PPV for ERM removal.
Keywords: vitreoretinal surgery • clinical (human) or epidemiologic studies: outcomes/complications • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)