Comparison of ganglion cell and retinal nerve fiber layer thickness in primary open-angle glaucoma and normal tension glaucoma with spectral-domain OCT.

BACKGROUND: The aim of this study was to evaluate the macular thickness (MT), ganglion cell complex (GCC), and circum-papillary retinal nerve fiber layer (RNFL) thickness in primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG) with spectral domain optical coherence tomography (SD-OCT).
METHODS: A total of 169 subjects were enrolled: 52 normal subjects, 61 with POAG, and 56 with NTG. Spectral-domain optical coherence tomography (SD-OCT) was used to analyze MT, GCC, and RNFL thickness. To compare the discrimination capabilities between the MT, GCC, and RNFL thickness measurements, we analyzed the areas under the receiver operating characteristic (ROC) curves (AUCs). The relationships between GCC and RNFL measurement and also the relationships of the groups, with age, gender, GCC, and RNFL thickness were assessed.
RESULTS: Normal subjects showed the thickest superior and inferior GCC, followed by in order NTG and POAG (p < 0.05). While there was a statistically difference in MT value of the normal subjects and the glaucoma patients (p < 0.05), MT value did not differ between POAG and NTG (p < 0.05). RNFL thickness parameters were significantly greater in normal subjects, followed in order by the NTG, and POAG (p < 0.05). Between the normal and entire glaucoma groups, all GCC and RNFL parameters showed the similar discrimination power. RNFL thickness parameters correlated significantly with all GCC thickness (p < 0.05). Superior RNFL thickness was the only independent variable between the POAG and NTG patients (odds ratio (OR) 0.942, p = 0.004, 95 %CI 0.905-0.981).
CONCLUSIONS: SD-OCT evaluation results suggest higher GCC and RNFL parameters for NTG than POAG.