| Objective:To describe and analyze the structural characteristics of the optic nerve head using SD-OCT(Spectral-domain optical coherence tomography)technology,such as the thickness of the retinal nerve fiber layer(RNFL),the thickness of the ganglion cell complex(GCC),the ratio of the cup to disc of the optic papilla,and the border tissue of Elschnig in healthy people and glaucomatous patients.To assess the changes of the structure of the optic nerve head in open-angle glaucoma patients.Methods:Descriptive study and case-control study.The information was collected and recorded from patients who visited our hospital from August 2020 to January 2023.The SD-OCT scans of the subjects were performed,including ONH(Optical nerve head)mode,GCC mode,Raster mode,and radial mode centered on the optic disc.The RNFL thickness,GCC thickness,and cup-to-disc ratio around the optic disc were measured by software.The border tissue of Elschnig and the Bruch’s membrane around the optic disc were outlined in each optic disc-centered Radial mode tomographic image,and the degrees of the tilt and the vertex angle of the border tissue of Elschnig were measured.The relationship between peripapillary RNFL thickness,GCC thickness,and intraocular pressure with age in normal subjects were analyzed,and the distribution characteristics of different forms of the border tissue of Elschnig in each area were described.Between the glaucoma group and the control group,the differences of the RNFL thickness,the thickness of GCC,the cup-to-disc ratio,and the distribution of the configuration of the border tissue of Elschnig were compared.Results:A total of 149 subjects were included in this study,including 16 patients(20 eyes)in primary open-angle glaucoma(POAG)group and 133 cases(223 eyes)in control group.In the healthy group,The RNFL thickness around the optic disc decreased significantly with age(r=-1.41,P=0.026),and was significantly negatively correlated with cup-to-disc ratio.Mean GCC thickness did not differ between men and women(P=0.232),and peripapillary RNFL thickness was significantly thicker in the superior area than the inferior area(P=0.004).According to the measurement of the angle,the tilt angle of the border tissue of Elschnig was classified into 3 types:nonoblique,internally oblique,and externally oblique,and the vertex angle of the border tissue of Elschnig was classified into 4 types:type 0,type 1,type 2,and type 3.The distribution of the four types of the vertex angle of the border tissue of Elschnig differed significantly among the eight regions surrounding the optic disc in healthy subjects.Type 1 of the vertex angle of the border tissue of Elschnig was the most common,accounting for 68.5%of the healthy group,and were mainly distributed in the superior temporal region.The distribution of each tilt type of the border tissue of Elschnig was significantly different among the eight regions(P=0.004),with externally oblique of the border tissue of Elschnig being the most common around the optic disc,mainly distributed in the temporal upper region,temporal lower region,and inferior temporal region in healthy eyes,and mainly in the temporal lower region of the openangle glaucoma group.In the superior temporal region,open-angle glaucoma patients had significantly more type 3 of the vertex angle of the border tissue of Elschnig than controls(P=0.001).In the superior nasal region,open-angle glaucoma patients had more nonoblique of the border tissue of Elschnig than controls(P=0.001),and in the temporal upper region,open-angle glaucoma patients had less externally oblique of the border tissue of Elschnig than controls(P=0.045).The ratio of optic cup to optic disc area,vertical diameter,and horizontal diameter were significantly greater in the openangle glaucoma group than the controls,and the GCC thickness and RNFL thickness were significantly less than the controls.Conclusion:The distribution of the various configuration of the border tissue of Elschnig was different in the eight areas around the optic disc of the healthy people.Compared the control group,the configuration of the border tissue of Elschnig in the glaucoma group has significant difference.The thickness of peripapillary RNFL became thinner with age,and was significantly correlated with GCC and optic disc rim.The different structural and histological characteristics of the optic nerve head may play an important role in the development of the primary open-angle glaucoma. |
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