Dynamics of the retinal microvasculature and morphology in Type 2 diabetes

Abstract

Purpose : To examine the longitudinal alterations of the microcirculation and inner retinal structure in patients with in Type 2 diabetes.

Methods : We analyzed data from a longitudinal study ranging over three years. Altogether 71 patients were enrolled and divided into two groups: eyes without and with mild diabetic retinopathy (DM and MDR, n=58 and n=33, respectively). We also enrolled 26 healthy subjects as controls. The subjects were imaged by SD-OCT (Spectralis, Heidelberg Engineering, Germany) and also by the Retinal Fundus Imager (RFI, Optical Imaging, Israel). The OCT volumes were segmented by OCTRIMA 3D while the RFI was used to measure retinal blood flow velocity (BFV) and blood flow rate (BFR). We extracted a total of 7 layers in all scans and calculated an average thickness in the nine ETDRS regions for all layers. Linear regression was performed to assess the changes over time. A mixed model analysis of variance was also applied for the interaction of time and group, accounting for inter-eye bias. The level of significance was set at 0.005.

Results : For both groups, we found that the superior-inferior blood flow rate difference (mean values) in the arteries were significantly negatively correlated with the thickness of the inner nuclear layer (INL) in the central ETDRS subfield (r=-0.464, p≤ .001). We also found that mean blood flow velocities in the arteries were significantly positively correlated with the thickness of the inner nuclear layer (INL) in the inner inferior region (r=0.329, p≤.007). The post-hoc least significant difference tests showed that the MDR group had less blood flow velocity in the arteries than the healthy (p=0.002) or the DM group (p=0.005), but that healthy and DM were not different from each other (p=0.430). The post-hoc least significant difference tests also showed that the blood flow velocity (BFV) in the veins for the Healthy group was different from the DM (p=0.002) and MDR (p<0.001) groups which were not different from each other (p=0.118).

Conclusions : As in previous studies, our results demonstrate the vascular impairment trend in diabetic patients with retinopathy and support the view that irregularities in vessel function exist in diabetic eyes before the development of clinically apparent retinopathy.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.