Accuracy of funduscopy to identify true edema versus pseudoedema of the optic disc

Differential diagnosis between acute optic disc edema (ODE) and optic disc pseudoedema (PODE) may be a clinical challenge even for well-trained ophthalmologists. Funduscopy remains the first-line investigation. The aim of this study was to assess the accuracy, sensitivity, and specificity of funduscopy in differentiating ODE from PODE.

This was an observational, cross-sectional, two-center study of subjects referred for presumed acute ODE. During funduscopy, each observer completed a form concerning the presence/absence of the 10 conventional signs of ODE. Seventy-four patients with ODE and 48 subjects with PODE were included in the analysis. Accuracy, sensitivity, and specificity from all possible combinations of signs were calculated by support vector machine (SVM) analysis.

As a single sign, the swelling of the peripapillary retinal nerve fiber layer had the highest accuracy (0.92; 95% confidence interval [CI], 0.82-0.97). Little variation was observed when more than fours signs were present. The best four-sign combinations were SWELLING, HEMORRHAGES, papilla ELEVATION, and CONGESTION of peripapillary vessels (accuracy, 0.93; 95% CI, 0.83-0.98; sensitivity, 0.95; specificity, 0.89). The presence of retinal or choroidal folds appeared to be a pathognomonic sign of true ODE (100% sensitivity) but had a low rate of presentation (23%).

The presence of at least four ophthalmoscopic signs (with the sign "swelling" included) gives the highest accuracy. Furthermore, peripapillary retinal folds seem to be related exclusively to ODE because they were never observed in our PODE group. These data may be useful for clinicians when evaluating patients referred for presumed optic disc edema in the acute phase.