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

Purpose: Differential diagnosis between true optic disc edema(ODE) and optic disc pseudo-edema (PODE) remains a clinicalchallenge even for experienced neuro-ophthalmologists. The aim of the study was to assess the accuracy, sensitivity, and specificity of the funduscopic diagnosis of ODE.Methods: Observational, cross-sectional, two-center study ofsubjects referred for presumed acute ODE. Fundoscopy wasconducted in each center by two blinded neuro-ophthalmologistswho completed a forced-choice form concerning thepresence/absence of the ten clinical signs of ODE. Data from 122patients were used for modeling analysis. There were 74 patients in the ODE group and 48 patients in the PODE group. Main outcome measures were accuracy, sensitivity, and specificity in identifying true ODE from all possible combinations of ophthalmoscopic signs, provided by Support Vector Machine (SVM) analysis.Results: To identify ODE the sign SWELLING (i.e., swelling of theperipapillary retinal nerve fiber layer) had the highest accuracy(0.92; 95% CI: 0.82–0.97). All three outcomes showed littlevariation when the combination consisted of more than four signs.The best four-sign combination was: SWELLING, HEMORRHAGES,papilla ELEVATION, and CONGESTION of peripapillary vessels(accuracy = 0.93, 95% CI: 0.83–0.98; sensitivity = 0.95; andspecificity = 0.89).Conclusions: In our series of presumed ODE, 48/122 (39%) caseswere finally diagnosed as PODE. The sign SWELLING had thehighest accuracy as a single sign, and was a component of the most accurate combinations of signs. Accuracy reached a high plateau level if at least 4 (out of 10) ophthalmoscopic signs were present.