98th Annual Meeting DOG 2000

K 188

Topographic retinal thickness measurement by optical coherence tomography in diabetic patients with and without diabetic retinopathy

U. Schaudig, F. Scholz, C. Glaefke

Background: Measurement of retinal thickness using two dimensional cross sectional images produced by optical coherence tomography (OCT) can be performed either on single scans or by an integrated computed algorithm. This study aimed to find topographic differences in central retinal thickness measured by an integrated software between normals and diabetic patients with and without diabetic retinopathy.

Methods: We studied 20 diabetic patients without (group 1) and 20 patients with diabetic retinopathy (group2) and no clinical significant macular edema. 25 normal healthy subjects were studied as a control group. Six radial 5 mm linear scans rotated at 30 degrees through the center of fixation were performed. Measurement of retinal thickness was done using an integrated threshold-based algorithm. The software composes a false-color coded retinal thickness map based on 600 single measurements and produces mean values of retinal thickness for the macula and 8 regions in a nasal, inferior, temporal and superior quadrant around the macula.

Results: Differences (Mann-Whitney test) were only found between groups 0 and 1 and groups 0 and 2. Statistically significant differences were found in the nasal quadrant (p=0,027 und p=0,018, respectively) and in the macula (p=0,031 und p=0,013, respectively). In 9 % of the eyes, the automated algorithm failed to produce valuable data because of insufficient quality of one or more oft the six scans.

Discussion: Significant differences between retinal thickness in healthy subjects and diabetics with and without diabetic retinopathy are present in specific areas around the macula and in the macula. The study supports previous findings based on non-algorithm based measurements. Increased scanning speed and software modifications are necessary to improve topographic measurements of retinal thickness by OCT in the future.

Augenklinik, Universit├Ąts-Krankenhaus Eppendorf, Martinistrasse 52, 20246 Hamburg