Macular Inner Plexiform and Retinal Nerve Fiber Layer Thickness in Glaucoma

Purpose. To compare the parameters of the macular ganglion cell-inner plexiform layer (mGCIPL) thickness measured by Cirrus high-definition optical coherence tomography in normal-tension glaucoma (NTG) and primary open-angle glaucoma (POAG). Methods. Eighty patients with NTG, 80 patients with POAG, and 100 normal control subjects were enrolled. The mGCIPL and peripapillary retinal nerve fiber layer (pRNFL) thicknesses measured by Cirrus high-definition optical coherence tomography were compared in patients with glaucoma. The areas under the receiver operating characteristic curve (AROCs) were calculated to compare the diagnostic power of the mGCIPL thickness with that of the pRNFL thickness. Pearson correlation coefficients were determined to investigate the correlation between the mGCIPL or pRNFL thickness parameters and the mean deviation (MD) values of visual field tests. Results. All parameters of the mGCIPL thickness were significantly different between normal control subjects and patients with glaucoma. The superior, superotemporal, and superonasal thickness of mGCIPL and the superior thickness of pRNFL showed significant reductions and significantly higher AROCs for distinguishing between normal eyes and eyes with glaucoma in POAG compared with those in NTG. In NTG or POAG groups, the mGCIPL and pRNFL parameters with the highest AROC were the minimum and average thickness, respectively. The average, minimum, inferior, inferotemporal, and inferonasal thickness of mGCIPL and the average and inferior thickness of pRNFL were correlated with MD in NTG (p < 0.05 for all parameters), whereas all parameters of the mGCIPL thickness except the inferonasal thickness and all parameters of the pRNFL thickness except the temporal thickness were correlated with MD in POAG (p < 0.05 for all parameters). Conclusions. The diagnostic ability of the mGCIPL thickness was comparable to that of the pRNFL thickness in patients with NTG or POAG. The mGCIPL loss in NTG was localized and mainly concentrated on the inferior portion compared with diffuse mGCIPL loss in POAG.