Optical coherence tomography in the differential diagnosis of true edema versus pseudoedema of the optic disc

Purpose To assess the predictive value of Spectral Domain OCT (SD-OCT) to discriminate between pathological true optic disc edema (ODE) and mimickers responsible for pseudoedema (PODE). Methods We carried out an observational cross-sectional study of subjects consecutively referred from 2011 to 2017 to the Neuro-Ophthalmology service of 4 different hospitals for presumed acute ODE. Among a total of 155 eyes, 95 were identified as ODE and 60 as PODE. Patients underwent the optic nerve OCT evaluation using Zeiss Cirrus Optic Disc Cube 200x200 analysis. Average and four principal quadrants RNFL values were compared between ODE and PODE groups and then with age-matched controls. ROC curve and AUC were calculated to determine optimal cut-off values. Mann-Whitney and chi-square tests were used to compare groups. Statistical correlation was tested by Spearman's rho test. All tests were two sided with p<.05 being considered statistically significant. Statistical analysis was performed with IBM SPSS Statistics 24. Results Average and RNFL thickness of each optic nerve quadrants resulted significantly higher in ODE compared to control and PODE; among quadrants, the highest correlation was reported for the inferior one. Combining the appropriate cut-off value for average and inferior quadrant, we found a negative predictive value of 91% for ODE when compared to PODE. No statistically significant differences were seen between control and PODE. Conclusions Our data show the usefulness of SD-OCT in the management of acute optic disc elevation of uncertain causes. In particular, the results herein reported provide high negative predictive value in differentiating benign mimickers from true edema of the optic disc, thus avoiding misdiagnosis and invasive procedures not necessary for such patients.