K 327
Quantitative and objective topometric analysis of optic nerve head drusen (ONHD) using Heidelberg Retina Tomograph (HRT)
J. Kuchenbecker, T. Wecke, C. K. Vorwerk, W. Behrens-Baumann .
Aim of the study: Optic nerve head drusen (ONHD) are one of the most frequent causes for congenital swelling of the optic nerve head. The Heidelberg Retina Tomograph (HRT) allows a three-dimensional topometric analysis of optic nerve disc. The present study focuses on the possibility to analyze superficial optic nerve head drusen quantitatively, and to obtain objective topometric data with the HRT.
Patients and methods: 18 eyes from 9 patients with sonographic confirmed drusen were analyzed with the HRT. We included in the topometrical analysis of the disc the following parameters: "disc area", "cup area", "rim area", "cup/disk ratio", "cup volume", "rim volume", "volume above surface", "mean retinal nerve fiber layer (RNFL) thickness" and "RNFL cross section area". The group was compared to 18 eyes from 9 matching healthy individuals. Statistic significance was done by using the t-test and Anova.
Results: Excluding the "RNFL cross section area" we found a significant difference in all measured parameters (p<0,05) between the two groups. The absolute frequency of the "volume above surface" of optic nerve head drusen revealed a peak from 0,25 - 0,5mm3 (7 from 18 eyes), whereas in normal eyes a peak from 0 - 0,25mm3 (17 from 18 eyes) was observed. The sectored analysis of the "volume above surface" of optic nerve head drusen showed in the nasal quadrant the highest (0,16 mm3) and temporal inferior the lowest (0,08 mm3) average.
Conclusions: The most relevant parameter for the quantitative and objective assessment of superficial optic nerve head drusen is the "volume above surface" measurement. It opens the possibility for follow ups of optic nerve head drusen with the HRT.
Department of Ophthalmology, Otto von Guericke University Magdeburg, Leipziger Str. 44, D-39120 Magdeburg, Germany