Macular Structure Parameters as an Automated Indicator of Paracentral Scotoma in Early Glaucoma

Abstract

To evaluate the predictive ability of macular parameters defined in the significance map created using spectral-domain optical coherence tomography (SD-OCT) for paracentral visual field defects in early glaucoma. Prospective comparative study. We studied 78 early-glaucomatous eyes of 78 patients, who underwent SD-OCT and standard automated perimetry 10-2. Macular layer parameters included the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL) + inner plexiform layer (IPL), and RNFL + GCL + IPL. The minimal distance between the area with abnormal (P < 1%) thickness and foveal center was defined as the shortest distance. A wider area of an abnormally thinned (<1%) region, within either an inferior or a superior hemicircle with a diameter of 6 mm centered at the fovea, was defined as the macular abnormal area. A circumpapillary RNFL parameter was defined in its 36 sectors. Areas under the receiver operating characteristic curves (ROCs) were calculated to discriminate between eyes with (n = 39) and without (n = 39) paracentral visual field defects in the central 5 degrees. Measurement reproducibility was almost perfect in the macular parameters at P < 1% (intraclass correlation, 0.907-0.942). Areas under the ROC were significantly higher (P ≤ 0.01) in the macular parameters (0.870-0.930), including the shortest distance of GCL + IPL/RNFL + GCL + IPL, and the macular abnormal area of RNFL/GCL + IPL/RNFL + GCL + IPL than in the circumpapillary RNFL parameter (0.676). When specificity was fixed at ≥90%, the shortest distance of GCL + IPL (area under the ROC = 0.874) and the macular abnormal area of RNFL (area under the ROC = 0.894) showed sensitivities greater than 50%. Macular structural parameters defined on an SD-OCT significance map may be potentially useful predictors of the presence of paracentral scotoma.