Diagnostic ability of macular ganglion cell–inner plexiform layer thickness in glaucoma suspects

The purpose is to assess the diagnostic ability for early glaucoma of macular ganglion cell–inner plexiform layer (GCIPL) thickness in a Chinese population including glaucoma suspects. A total of 367 eyes with primary open-angle glaucoma (168 early glaucoma, 78 moderate glaucoma, and 121 advanced glaucoma), 52 eyes with ocular hypertension (OHT), 59 eyes with enlarged cup-to-disc ratio (C/D), and 225 normal eyes were included. GCIPL thickness (average, minimum, superotemporal, superior, superonasal, inferonasal, inferior, and inferotemporal), retinal nerve fiber layer (RNFL) thickness, and optic nerve head (ONH) parameters were measured using Cirrus high-definition optical coherence tomography (OCT) and compared. The diagnostic ability of OCT parameters was assessed by area under receiver operating characteristic curve (AUROC) in 3 distinguishing groups: normal eyes and eyes with early glaucoma, normal eyes and eyes with glaucoma regardless of disease stage, and nonglaucomatous eyes (normal eyes, eyes with OHT, and enlarged C/D) and early glaucomatous eyes. Glaucomatous eyes showed a significant reduction in GCIPL thickness compared with nonglaucomatous eyes. In all 3 distinguishing groups, best-performing parameters of GCIPL thickness, RNFL thickness, and ONH parameters were minimum GCIPL thickness (expressed in AUROC, 0.899, 0.952, and 0.900, respectively), average RNFL thickness (0.904, 0.953, and 0.892, respectively), and rim area (0.861, 0.925, and 0.824, respectively). There was no statistical significance of AUROC between minimum GCIPL thickness and average RNFL thickness (all P > .05). GCIPL thickness could discriminate early glaucoma from normal and glaucoma suspects with good sensitivity and specificity. The glaucoma diagnostic ability of GCIPL thickness was comparable to that of RNFL thickness.