Comparison of macular ganglion cell complex thickness by Fourier-domain OCT in normal tension glaucoma and primary open-angle glaucoma

Purpose: To compare perimacular ganglion cell complex (GCC) parameters between patients with normal tension glaucoma (NTG) and primary open-angle glaucoma (POAG). Methods: Participants, consecutively enrolled from January 2009 to June 2009, underwent optical coherence tomographic imaging with RTVue-100 (Optovue Inc, Fremont, CA). Optic nerve head (ONH) parameters, retinal nerve fiber layer (RNFL) parameters, and GCC parameters were acquired. Mean measurements of ONH, RNFL, and GCC parameters among the normal, NTG, and POAG groups were compared using analysis of variance. Area under the receiver operator characteristic curve was used to assess the ability of each parameter to detect glaucomatous changes. Results: Fifty-eight normal controls, 51 patients with NTG, and 52 patients with POAG were included. Mean measurements of ONH parameters were similar between the NTG and POAG groups (all P>0.05). Average RNFL thickness did not differ between the NTG and POAG groups (P=0.053), whereas average GCC thickness significantly differed between the NTG and POAG groups (P=0.001). In terms of pattern-based parameters of GCC, focal loss volume did not differ between the NTG and POAG groups (P=0.165), whereas global loss volume was significantly higher in the POAG group (P<0.001). There were no statistically significant differences between RNFL and GCC measurements with respect to the ability to detect glaucomatous changes. Conclusions: GCC loss in the NTG group was more localized compared with diffuse GCC loss in the POAG group. Perimacular GCC parameters could be a good alternative or supplement to peripapillary RNFL measurements for diagnosis and research in patients with NTG.