Abstract
Purpose:
1) To determine when the foveal contour reaches its final observed configuration following surgery for idiopathic epiretinal membrane (ERM) as assessed with optical coherence tomography (OCT), 2) to determine the frequency of foveal contour change, and 3) to assess changes in central retinal thickness (CRT) and best corrected visual acuity (BCVA) in relation to baseline foveal contour.
Methods:
OCT images from 80 eyes of 80 consecutive subjects who underwent pars plana vitrectomy with membrane peeling for idiopathic ERM were analyzed retrospectively. Foveal contour was determined by the relative difference of the thickness at the fovea to the surrounding macula to classify as Grade 0 (foveal depression present), Grade 1 (fovea flat relative to macula), and Grade 2 (fovea thicker than surrounding macula). The average time between final observed contour grade and previously observed discordant grade was used to interpolate when conversion to final observed grade was expected to occur. CRT was calculated from the average foveal thickness of six radial line scans.
Results:
Average conversion to final observed foveal configuration occurred at postoperative day 98 (range: 4-549). Baseline Grade 0 (n=4) and Grade 1 (n=31) (Grade 0/1) eyes reached their final observed foveal configuration on average at postoperative day 85 (range: 4-386); baseline Grade 2 (n=45) eyes reached their final observed foveal configuration on average at postoperative day 111 (range: 4-549) (p=0.554). Foveal depression (Grade 0) was observed in 19 of 80 eyes (23.8%) at last follow-up. CRT improved on average 129 μm. At last follow-up, baseline Grade 0/1 eyes (average: 321.9 days, range: 32-1028), improved CRT from 444.4 to 365.6 μm (p<0.001); baseline Grade 2 eyes (average: 365.0 days, range: 34-1302) improved CRT from 565.5 to 396.6 μm (p<0.001). At last follow-up, baseline Grade 0/1 eyes improved BCVA from 0.48 to 0.31 LogMAR (Snellen equivalent [SE]: 20/60 to 20/41) (p<0.001); baseline Grade 2 eyes improved BCVA from 0.55 to 0.39 LogMAR (SE: 20/71 to 20/49) (p<0.001).
Conclusions:
Final foveal contour is most often observed between three and four months postoperatively and preoperative foveal contour confers no significance as to when this occurs. Reconstitution of the foveal depression should not be expected beyond four months after surgery as the majority of eyes (76.2%) do not achieve Grade 0 classification beyond this time.