Regression Analysis of Optical Coherence Tomography Disc Variables for Glaucoma Diagnosis

Abstract

Purpose To report diagnostic accuracy of optical coherence tomography (OCT) disc variables using both time-domain (TD) and Fourier-domain (FD) OCT, and to improve the use of OCT disc variable measurements for glaucoma diagnosis via regression analyses that adjust for optic disc size and axial length-based magnification error Design Observational, cross-sectional Participants 180 normal eyes of 112 participants and 180 eyes of 138 participants with perimetric glaucoma from the Advanced Imaging for Glaucoma (AIG) Study Methods Diagnostic variables evaluated from TD-OCT and FD-OCT were: disc area, rim area, rim volume, optic nerve head volume, vertical cup-to-disc ratio (CDR), and horizontal CDR. These were compared to overall retinal nerve fiber layer (RNFL) thickness and ganglion cell complex (GCC). Regression analyses were performed that corrected for optic disc size and axial length. Area-under-receiver-operating curves (AUROC) were used to assess diagnostic accuracy before and after the adjustments. An index based on multiple logistic regression that combined optic disc variables with axial length was also explored with the aim of improving diagnostic accuracy of disc variables. Main Outcome Measure Comparison of diagnostic accuracy of disc variables, as measured by area-under-receiver operating curves Results The unadjusted disc variables with the highest diagnostic accuracies were: rim volume for TD-OCT (AUROC=0.864) and vertical CDR (AUROC=0.874) for FD-OCT. Magnification correction significantly worsened diagnostic accuracy for rim variables, and while optic disc size adjustments partially restored diagnostic accuracy, the adjusted AUROCs were still lower. Axial length adjustments to disc variables in the form of multiple logistic regression indices led to a slight but insignificant improvement in diagnostic accuracy. Conclusions Our various regression approaches were not able to significantly improve disc-based OCT glaucoma diagnosis. However, disc rim area and vertical CDR had very high diagnostic accuracy, and these disc variables can serve to complement additional OCT measurements for diagnosis of glaucoma.

Agreement between the newly developed OCT glaucoma staging system and the standardized visual field glaucoma staging system 2

“…The present study also showed a moderate positive correlation between GSS2 and the cup-to-disc ratio, which is consistent with that of Richter et al, 18 who reported that the disc rim area and vertical CDR had very high diagnostic accuracy and could complement additional OCT measurements for the diagnosis of glaucoma.…”