Repeatability of Retinal Macular Thickness Measurements in Patients with Clinically Significant Macular Edema Using Two Different Scanning Protocols of Spectralis Optical Coherence Tomography.

OBJECTIVE

To determine the repeatability of Spectralis optical coherence tomography (OCT) retinal thickness measurements in diabetic patients with clinically significant macular edema (CSME) using two different scanning protocols.

METHODS

Seventy-one eyes of 71 diabetic patients with CSME were included in the study. Coefficients of repeatability and intrasession variation coefficients were tested with 20 × 15 degree raster scans consisting of 19 or 37 high-resolution line scans (15 or 8 frames per scan, respectively) that were repeated 2 times by 1 experienced examiner. The first scan was set as the reference scan; the second scan was the follow-up scan and was performed with the use of the follow-up mode.

RESULTS

The mean and standard deviation for the central foveal subfield (CSF) using the first scanning method was 404 ± 88 μm, while it was 399 ± 86 μm using the second protocol, which was not statistically significantly different (p = 0.35, paired test). Particularly examining the CSF, the coefficient of repeatability was 1.48 (6.00 µm) and 1.49 (5.95 µm) for the 19- and the 37-B-scan acquisition, respectively, showing a nonstatistically significant difference (p < 0.001).

CONCLUSIONS

Retinal thickness measurements in diabetic patients with CSME are repeatable using both scanning protocols (19 or 37 B-scans) with Spectralis OCT. The repeatability of the retinal thickness measurement does not improve by increasing the number of B-scans from 19 to 37.