A comparative evaluation of segmental analysis of macular layers in patients with early glaucoma, ocular hypertension, and healthy eyes

Abstract

To compare macular layer thicknesses between early glaucoma, ocular hypertension, and healthy eyes and to evaluate the accuracy of spectralis optical coherence tomography (OCT) segmentation software in discriminating early glaucoma from ocular hypertension and healthy eyes. OCT scans were performed using the standard macular and peripapillary retinal nerve fiber layer (pRNFL) protocols on the Spectralis-OCT. The following macular thickness parameters were compared in the inner and outer circles of the Early Treatment Diabetic Retinopathy Study: total macular thickness (MT), retinal nerve fiber layer (mRNFL), ganglion cell layer (mGCL), inner plexiform layer (mIPL), inner nuclear layer (mINL), outer plexiform layer (mOPL), outer nuclear layer (mONL) and ganglion cell complex (mGCC: sum of mRNFL, mGCL, and mIPL). Sectors and layers with the best area under the receiver operating characteristic curve (AUC) were determined and compared between groups. Of a total of 200 eyes included in this study, 64 eyes had primary open angle glaucoma, 69 had ocular hypertension, and 67 were healthy. Peripapillary RNFL was significantly thinner in the early glaucoma group (P<0.05). For the macular variables, there was a significant reduction in the MT, mGCC, mRNFL, mGCL, and mIPL thicknesses in the early glaucoma group; while there were no statistically significant differences between the ocular hypertension and control groups (P>0.05). For distinguishing early glaucoma from normal eyes, AUCs for mGCC, mGCL, and mRNFL were similar to the pRNFL; and for early glaucoma and ocular hypertension, AUCs for mGCC, mGCL mRNF and mIPL were comparable to the pRNFL. Macular segmentation can assist in the early diagnosis of glaucoma as a complementary study to pRNFL analysis.