A mode optic nerve ultrassonography for glaucoma diagnosis

Abstract Objectives: Determine if retrobulbar optic nerve horizontal diameter measurement or reflectivity correlates with the optic disc excavation diameter relation in glaucoma, considering: measurements correlation, the sensitivity and specificity between the methods and which value has greater sensitivity and specificity to differentiate patients with and without glaucoma. Methods: In a masked study, the optic nerves of 38 patients with open angle primary angle glaucoma and 37 control patients were examined for retrobulbar echographic determination of their A mode (DNA) and their reflectivity (RNA) diameters. Biomicroscopically the relationships of the vertical or horizontal length of the excavation by the corresponding diameter of the optical discs (EV / DV or EH / DH) were estahed. These measures were evaluated for their correlations, consistencies, sensitivities and specificities. Results: Mean DNA was 2.93 mm in the control group and 2.72 mm in the glaucomatous group (p <0.001) and that of the RNA was 32.22% in the control group and 31.59% in the glaucomatous group (p = 0.577). DNA was moderately and significantly correlated with EH / DH (-0.450, p <0.01) and EV / DV (-0.463, p <0.01) and RNA correlated insignificantly with DH / DH and EV / DV. DNA measurements was 0.6780 (95% CI: 0.5883-0.7561) and RNA was 0.6902 (0.6010-0.7640) and were lower than the consistency measurements of the disc. The measurement of 2.85 mm of DNA was the one of greater sensitivity (0.757) and specificity (0.714) for diagnosis of glaucoma. Conclusion: The standard method A of retrobulbar optic nerve diameter measurement was the most suitable for glaucoma diagnostic.