Epiretinal membrane as a source of errors during the measurement of peripapillary nerve fibre thickness using...

We aimed to examine the extent to which measurement errors in the determination of retinal nerve fibre layer (RNFL) using spectral-domain optical coherence tomography (SD-OCT) occur in cases of epiretinal membrane and whether systematic deviations are found in the values obtained.

A macular scan and a circumpapillary scan were performed on 97 eyes of 97 patients using SD-OCT. Group 1 comprised 53 patients with epiretinal membrane at an age of 70 ± 4.8 years (median ± average absolute deviation). Group 2 consisted of 44 patients without any macular pathologies (median age 70 ± 5.8 years). Differences in the thickness of the RNFL and segmentation errors in the detection of the RNFL were recorded quantitatively in both groups and checked for statistical significance using non-parametric tests.

The median central retinal thickness in Group 1 was 357 ± 79 μm (median ± average absolute deviation), and in Group 2 it was 270 ± 11 μm (p < 0.001). The result of the quadrant-by-quadrant measurement of the average RNFL in Group 1 and Group 2, respectively, was: temporal 88 ± 17 and 73 ± 9 μm, inferior 121 ± 17 and 118 ± 15 μm, nasal 87 ± 15 and 89 ± 14 μm and superior 115 ± 15 and 114 ± 9 μm. Temporally, the difference was statistically significant (p < 0.001). Segmentation errors of the RNFL were found in 19 of 53 eyes (35.8 %) in Group 1 and in no eyes (p < 0.001) in Group 2.

In eyes with epiretinal membrane, measuring errors in the SD-OCT occur significantly more frequently than in eyes without any retinal pathologies. If epiretinal membrane and glaucoma are present simultaneously, the results of the automated RNFL measurement using SD-OCT should be critically scrutinised, even if no papillary changes are visible clinically.