A new strategy to interpret OCT posterior pole asymmetry analysis for glaucoma diagnosis.

AIM: To detect early glaucoma by optical coherence tomography (OCT) posterior pole asymmetry analysis.
METHODS: Totally 39 eyes from 39 healthy subjects, 40 eyes from 40 mild glaucoma patients, 33 eyes from 33 moderate glaucoma patients and 41 eyes from severe glaucoma patients were included in this study. All subjects underwent posterior pole asymmetry analysis (PPAA) of OCT and the posterior pole area was divided into three zones. Means, standard deviations and 95% confidence intervals of each zone asymmetry in control group were assessed. Retina thickness asymmetry (RTA) of different stage of glaucoma were compared for each zone, and receiver operating characteristic (ROC) curves were made to test the efficacy of strategies using different zones to discriminate glaucomatous eyes from the healthy ones.
RESULTS: In a healthy population, RTA of the centre zone showed the minimal mean value (3.085 µm), standard deviation (1.756), and the narrowest 95% confidence interval (from 2.360 to 3.810 µm). It was only in the center zone that RTA exhibited significant difference between control and moderate glaucoma group (P<0.01), as well as control and severe glaucoma group (P<0.00001). The strategy utilized in the center zone had the strongest diagnostic capability (zone 3 AUROC=0.816, P=0.0016) in comparison to that of the periphery area (zone 1 AUROC=0.675, P=0.0016; zone 2 AUROC=0.623, P=0.0197), the whole posterior pole involved interpreting strategy showed inferior diagnostic power than the centre zone dependent strategy (z=2.851, P=0.0044).
CONCLUSION: Utilizing the posterior pole centre zone to interpret OCT PPAA results are more effective than making use of the whole posterior pole map.