Purpose:
To assess the performance of the back-scattering measurement determination of intraretinal layers in healthy normal and type 1 diabetic eyes using optical coherence tomography (OCT) along with a single and multiple back-scattering model.
Methods:
Unprocessed raw scan data were exported from the Stratus OCT machine after performing standard macular mapping in 74 healthy eyes, 39 eyes with type 1 diabetes mellitus (DM) with no retinopathy, and 36 eyes with diabetic retinopathy (MDR) on biomicroscopy. Automatic layer segmentation was performed using OCTRIMA. Mean values of relative internal reflectivity (RIR) and reflectivity with normalization to the RPE reflectance (NRPE) were used in the comparisons. Mean light-backscattering and scattering coefficients of the intraretinal layers were calculated by using single and multiple scattering models. Mann-Whitney U test was used to test for differences between the groups (p<0.001 was considered statistically significant).
Results:
Scattering coefficients were significantly different between MDR and healthy eyes for the INL, IS/OS junction, OS and OS/RPE junction when mean values of RIR were analyzed. When comparing NRPE values between the above groups, significant differences were also found for the OS and OS/RPE junction . Moreover, scattering coefficients were significantly different between MDR and DM eyes for the OS and OS/RPE junction for both types of normalization used .
Conclusions:
Our results suggest that the optical properties of the intraretinal layers may provide useful information to differentiate DM and MDR eyes from healthy eyes. It appears that diabetes also inflicts additional damage to the outer retinal segment demonstrated by the optical changes of the OS and RPE, which could be an additional indicator to differentate diabetic eyes with and without early retinopathy. Further research is warranted to determine how this approach may be used to improve diagnosis of diabetes.
Keywords: image processing • diabetic retinopathy • optical properties