Date Published: May 12, 2016
Publisher: Public Library of Science
Author(s): Mona Laible, Sven Jarius, Friedericke Mackensen, Annette Schmidt-Bacher, Michael Platten, Jürgen Haas, Philipp Albrecht, Brigitte Wildemann, Christoph Kleinschnitz.
To improve the detection of retinal nerve fiber layer (RNFL) thinning in multiple sclerosis (MS), a special peripapillary ring scanning algorithm (N-site RNFL, N-RNFL) was developed for spectral domain optical coherence tomography (SD-OCT). In contrast to the standard protocol (ST-RNFL) scanning starts nasally, not temporally, and provides an additional sector of analysis, the papillomacular bundle (PMB). We aimed to ascertain whether the temporal RNFL differs between the two techniques, whether N-RNFL is more sensitive than ST-RNFL to detect previous optic neuritis (ON), and whether analyzing the PMB adds additional sensitivity. Furthermore, we investigated whether RNFL is associated with disease severity and/or disease duration.
We conducted a cross-sectional case-control study of 38 patients with MS, of whom 24 had a history of ON, and 40 healthy controls (HC). Subjects with ON within the previous 6 months were excluded. Records included clinical characteristics, visual evoked potentials (VEP), and SD-OCT in both techniques.
In a total of 73 evaluable MS eyes, temporal N-RNFL was abnormal in 17.8%, temporal ST-RNFL in 19.2%, and the PMB-RNFL in 21.9%. In ON eyes, the sensitivity of temporal N-RNFL and ST-RNFL did not differ significantly (37.0%/33.3%, p = 0.556). The sensitivity of VEP was 85.2%. RNFL thickness was associated with disease severity in all eyes, with and without a history of ON, and with disease duration.
The two OCT techniques detected previous ON with similar sensitivity, but the sensitivity of VEPs was superior to that of both N-RNFL and ST-RNFL. Our results indicate that the widely used ST-RNFL technique is appropriate for peripapillary RNFL measurements in MS patients.
Optical coherence tomography (OCT) allows precise measurement of retinal nerve fiber layer (RNFL) thickness and is thus a promising tool for the detection of prior optic neuritis (ON). Numerous studies have used OCT to detect and characterize thinning of the peripapillary RNFL in the context of multiple sclerosis (MS) [1–5], clinically isolated syndrome suggestive of MS (CIS) , or as an isolated syndrome .
We used sensitivity for a history of ON as a paradigm for the assessment of axonal loss in MS. The major findings of our study are the following: (1) We observed no significant change in the sensitivity for former ON when applying the N-RNFL protocol with the PMB as an additional sector. (2) OCT had lower sensitivity than VEP in post-ON eyes. (3) The combination of OCT and VEP did not increase sensitivity. (4) N-RNFL and ST-RNFL were correlated with corrected VA and EDSS in eyes without previous ON, and global N-RNFL correlated with corrected VA in all MS eyes. We observed no significant differences in the ability to detect previous clinically apparent ON between ST-RNFL and N-RNFL methods as determined by global and sectorial RNFL thickness. Although separate assessment of the PMB sector using N-RNFL depicted ON with a trend towards higher sensitivity (48.1%) compared with global measures from both measurement algorithms (42.3 and 33.3%), this difference was not statistically significant. This is in line with a former observation in patients with at least one former ON . In this study, focusing on RNFL analysis in the temporal sector did not increase the sensitivity for ON. However, the study did not apply the N-RNFL protocol and therefore, cannot comment on isolated PMB RNFL values.