Analysis of Z-profile Signal Width for the Demonstration of Neuroretinal Rim Using the Heidelberg Retina Tomograph (HRT)
Schmidt E.1, Scheuerle A. F.2, Pillunat L. E.1
1Universitäts-Augenklinik Dresden; 2Universitäts-Augenklinik Heidelberg
Purpose: Form and size of neuroretinal rim are among the most important parameters evaluating glaucomatous damage to the optic disc. The macular module of the Heidelberg Retina Tomograph analyses the z-profile signal width togeather with the reflectivity in all pixels. The resulting value is called e. We investigated if the neuroretinal rim can be demonstrated using the macular module and if this mode allows the differentiation of healthy and glaucomatous optic discs.
Method: From the groups 1) healthy, 2) moderate glaucoma und 3) advanced glaucoma we examined 20 eyes respectively. Classification was based upon visual field, intraocular pressure, funduscopy and HRT-parameters. 15°-HRT II scans of each eye were performed and analysed by the macular module software. Results were compared interindiviually and correlated to clinical aspects.
Results: Especially optic discs with medium or large cupping were suitable for demonstration of neuroretinal rim by e-values. Healthy optic discs showed the widest, glaucomatous ones showed the narrowest rim area. Defects of nerve fiber bundles often were associated with rim notches. The demonstration of neuroretinal rim by e-values appeared to be difficult for healthy optic discs with a very small and shallow excavation.
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