Agreement Between Trend-Based and Qualitative Analysis of the Retinal Nerve Fiber Layer Thickness for Glaucoma Progression on Spectral-Domain Optical Coherence Tomography

Abstract

Introduction: To evaluate the agreement between trend-based analysis and qualitative assessment of the retinal nerve fiber layer (RNFL) thickness for glaucomatous progression on spectral-domain optical coherence tomography (SDOCT).

Methods: Retrospective review of 190 eyes from 103 patients with glaucoma or suspected glaucoma that underwent SDOCT imaging during four consecutive clinic visits. Trend-based progression was characterized by a significantly negative slope. Progression by qualitative analysis was determined by review of raw SDOCT B-scans.

Results: The slope was significantly greater in those with progression than without progression for both trend-based and qualitative analysis (p < 0.001). However, the qualitative grading classified a significantly greater proportion of eyes as progressing compared to trend-based analysis in both the superotemporal (ST) (23.2% vs. 10.5%, p = 0.001) and inferotemporal (IT) RNFL (27.4% vs 8.4%, p < 0.001). The trend-based and qualitative classifications of progression showed poor agreement in both the ST (kappa = 0.0135) and IT RNFL (kappa = 0.1222). The agreement between trend-based and qualitative analysis was lower for eyes with artifacts (ST = 58.11%; IT = 68.7%) than those without artifacts (ST = 80.2%; IT = 74.8%). Moreover, among eyes with artifacts, there was no significant difference in slope between those qualitatively categorized as progressing versus not progressing (p > 0.05).

Conclusions: Poor agreement was found between a trend-based and qualitative analysis of change in RNFL on SDOCT. Careful qualitative review of SDOCT imaging may identify specific areas of glaucoma progression not captured by trend-based methods, especially in the presence of artifacts. Such an approach may also prove useful for detecting glaucoma progression in a clinical setting when there are few data points available.

Keywords: Glaucoma progression; Qualitative; Retinal nerve fiber layer; Spectral-domain optical coherence tomography; Trend-based.

Fig. 1

The left panels show consecutive retinal nerve fiber layer change profiles over time which were generated by automated segmentation. The middle panels show the raw optical coherence tomography B-scan images. The right panels show the trend line and p value. In the left panels, the superotemporal area of red suggests possible progression by the change profile. However, close inspection of the raw B-scan in the middle panels reveals an epiretinal membrane that subsequently resolves (red arrows), suggesting that there is not true progression in the superotemporal quadrant according to qualitative analysis. The right superior panel demonstrates the trend line which is significantly negative for the superotemporal quadrant (p = 0.01). Thus, the superotemporal quadrant is miscategorized with progression if relying on trend-based analysis from automated segmentation, for it is shown to have false progression by qualitative analysis. In the middle panels, the yellow arrows highlight an area of true progression in the inferotemporal quadrant that is also seen in the change profile in the left panels. However, the right bottom panel shows that the trend-based analysis was not significantly negative in the inferotemporal quadrant (p = 0.07). This was an example of a false negative for progression if relying on trend-based analysis

Fig. 2

The top left panels show a change in the profile of the superotemporal nerve fiber layer between the first and the most recent visit, concerning for possible progression. The bottom panel shows a significantly negative slope by trend-based analysis. However, the raw optical coherence tomography B-scans in the upper right panels demonstrate that this change is due to a decrease in traction from the epiretinal membrane (red arrows), and is thus an example of false progression

Fig. 3

The left panels show a red area of change in the retinal nerve fiber layer profile of the superotemporal and inferotemporal quadrants. The bottom right panel also shows a significantly negative slope by trend-based analysis. However, qualitative assessment of the raw optical coherence tomography B-scans in the upper right panels demonstrate that the change is due to a release of vitreous traction (red arrows) and is thus an example of false progression