Abstract
Purpose: The aim of the present study was to investigate the diagnostic power of RGCL in the macula quantitatively and qualitatively by using a conventional and extended elliptic grid with deviation maps.Subjects and Methods: Thickness of RGCL was measured using SPECTRALIS® OCT (Heidelberg Engineering, Heidelberg, Germany) in 150 eyes of 150 subjects of the Erlangen Glaucoma Registry (EGR; NTC00494923): 26 ocular hypertension (OHT), 39 pre-perimetric open-angle glaucoma (pre-OAG), 19 normal tension glaucoma (NTG), 34 primary open-angle glaucoma (POAG), 16 secondary open-angle glaucoma (SOAG), and 16 controls. Analysis of RGCL was done quantitatively (global value, GV) and qualitatively (qualitative total value, QTV) by using a color-coded point score for data of the common elliptic macular grid of deviation maps. Furthermore, qualitative analysis of RGCL was done for an extended elliptic macula grid (extended qualitative total value, eQTV). Receiver operating characteristic (ROC) curves were calculated for the conventional and the enlarged macular grid for all subjects' groups.Results: GV of RGCL thickness differed significantly between pre-OAG (p < 0.05), NTG (p < 0.001), POAG (p < 0.001), SOAG (p < 0.001), yet not OHT (p > 0.05) and controls, respectively. Quantitative ROC analysis of GV showed AUC of 0.965 (SOAG), 0.942 (POAG), 0.916 (NTG), 0.772 (pre-OAG), and 0.526 (OHT). QTV differed significantly between pre-POAG (p < 0.05), NTG (p < 0.001), POAG (p < 0.001), SOAG (p < 0.001), yet not OHT (p > 0.05) and controls, respectively. Qualitative ROC analysis of QTV showed AUCs of 0.908 (NTG) 0.914 (POAG), 0.930 (SOAG), 0.734 (pre-POAG), and 0.519 (OHT). Implementation of eQTV yielded even higher AUCs for NTG (0.919), POAG (0.969), and SOAG (0.973) compared to GV. Similar AUCs of eQTV and GV were observed for OHT (0.514) and pre-OAG (0.770).Conclusion: The results of the present study showed that quantitative and qualitative analysis of RGCL thickness yielded similar diagnostic impacts compared to RNFL. Qualitative analysis might be a quick and easy useable tool for clinical all-day life. The present data suggest that analysis of an extended macula region might improve its diagnostic impact.
Highlights
Glaucoma is one of the most common causes of blindness worldwide
The aim of the present study was to investigate the diagnostic power of only RGC layer (RGCL) in the macula quantitatively and qualitatively by using a conventional and extended elliptic grid in patients with ocular hypertension (OHT), pre-perimetric open-angle glaucoma, normal tension glaucoma (NTG), primary open-angle glaucoma (POAG), and secondary open-angle glaucoma (SOAG) compared to controls
No significant difference was observed between OHT and controls (p > 0.05)
Summary
Glaucoma is one of the most common causes of blindness worldwide. The health burden caused by glaucoma increased in the last 25 years [1, 2]. Thereby, scan quality reaches to the level of histological images It seems to be more precisely than perimetry for diagnosing the progression of glaucoma in earlier stages [9]. To measurement of the peripapillary retinal nerve fiber layer (RNFL), RGC layer (RGCL) thickness can be quantified [10]. The RNFL thinning decreases in speed while glaucoma disease continues to progress. RGCL thickness continued to decrease constantly with glaucoma progression [9]. Analysis of RGCL thickness might offer an additional diagnostic parameter for revealing progression of glaucoma from early to advanced stages. In eyes with early pre-perimetric glaucoma average RGCL thickness and especially the inferior region of the macula RGCL were observed to be the most appropriate ones for diagnostics [7]. Implementation of enlarged grids for RGCL analysis, enabling analysis of larger macula regions, lead to an enhanced diagnostic power, as temporal quadrants of larger macular grids reached highest AUC value [11]
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