P 768Assessment of retinal thickness in macula holes by means of the Heidelberg Retina Tomograph (HRT)
E. Schmidt, A. F. Scheuerle, R. O. W. Burk
Objective: The in vivo-measurement of retinal nerve fiber layer thickness (RNFLT) faces many problems. Macula foramen of stage III and IV allow free visibility of the retinal pigmentary epithelium. In this trial we used scanning laser tomography for an in vivo examination of the retinal thickness.
Methods: Inclusion criteria was a flat bottom of the macula hole. To quantify possible elevations we placed a contur line right in the hole. The resulting "cup area" was to equal 0, the maximum "cup depth" must not exceed 30 m . 17 patients fit this selection. Operating with the analyse intensity-mode we obtained the z-values of the maximal reflectivity in the bottom of the macula hole, in the surrounding prominence and in the unaffected retina. The retinal thickness at a distance of 6o from the macula was calculated by substraction.
Results: The distance between the retinal surface and the bottom of the hole was 120 ± 34 m (mean ± SD). The average height of the surrounding prominence was 78 ± 43 m above the retinal surface.
Discussion: The calculated parameters of the retinal thickness showed a small standard deviation. We hypothize that in patients with macula hole one can assess the retinal thickness using the analyse intensity-mode of HRT. The calculated thickness of 120 m differs significantly from histologic exams though (220 m , Rohen 1977 in Naumann: Pathologie des Auges). Further investigations of the papillary and macular region in patients with macula holes might improve the precision of HRT measurements as reference height and RNFLT and so could enhance diagnostics in glaucoma.
Eye clinic University of Heidelberg, INF 400, D-69120 Heidelberg