P 429
Laser Scanning Morphometry of the optic disc and echographic optic nerve thickness in glaucoma
C. Y. Mardin
Purpose: Aim of this study was to investigate the correlation of intraocular morphometric measurements of the optic disc with retrobulbar measurements of the optic nerve sheaths. This question is of practical interest in eyes with opaque media, when conventional transpupillar examination of the optic disc is impossible.
Patients and methods: 42 eyes of 21 patients (age 57,8± 15,3a) of our Glaucoma Service with asymetric glaukomatous optic atrophy were prospectively examined. All eyes were devided in three diagnostic groups: ocular hypertensive, preperimetric and perimetric glaucomatous optic discs. In the course of a 24h-IOP profiles, static Octopus-perimetry, and morphometry of the optic disc with the HRT (Heidelberg-Engineering, Heidelberg, Version 2.01) were performed. Thickness of the optic nerve was measured with B-scan and its maximum pial, arachnoidal and dural diameter (Æ ) with standardised A-scan-echography. The results of both methods, perimetrys mean defect and highest IOP were correlated using the non-parametric Spearmans test.
Results: Max. Æ of all optic nerve sheath measurements (A-scan) correlated significantly with two- and three-dimensional HRT-measurements of the excavation, neuroretinal rim (NRR) and the perimetric mean defect ([R]³ 0,5, p=0,0001). The max. B-scan-Æ did not correlate with any HRT-measurement. The max. pial and arachnoidal Æ was significantly lower in the perimetric group than in the perimetric and ocular hypertensive group (p£ 0,01). The arachnoidal Æ of the optic nerve showed the highest correlation of all A-scan measurements with the variables of the HRT.
Discussion: Loss of NRR results in a reduced echographic Æ of all optic nerve sheaths. The retrobulbar standardised A-scan measurement of the optic nerve correlates sufficiently with the intraocular HRT-measurements of the optic disc. The measurement of the arachnoidal Æ seems to be most and the B-Bild-Æ least suitable to estimate the glaucomatous optic nerve head atrophy e.g. in eyes with opaque media.
Augenklinik mit Poliklinik Universität Erlangen-Nürnberg, Schwabachanlage 6, D-91054 Erlangen
Supported by Deutsche Forschungsgemeinschaft, SFB 539