Purpose: To evaluate retinal vessel diameters in relation to different severity grades of diabetic retinopathy (DR) using spectral-domain optical coherence tomography (SD-OCT).
Methods: Patients with varying degrees of nonproliferative DR (NPDR) underwent circular OCT scans centered on the optic nerve head using a SD-OCT. These cases were retrospectively reviewed. The presence and severity of DR was assessed using Early Treatment Diabetic Retinopathy Study protocols. The 5 largest retinal arterioles and venules were labeled and measured on OCT scans for each patient according to previously published methods. Vertical vessel inner contour diameter, vertical vessel outer contour diameter, and reflectance shadowing width were among the documented parameters.
Results: Of 59 eyes from 45 patients examined, 30 (50.2%) and 29 (49.8%) had mild and severe NPDR, respectively. Eyes with severe NPDR had narrower mean arteriolar vertical vessel inner diameter (87.9 ± 10.8 μm), vertical vessel outer diameter (119.1 ± 9.7 μm), and vessel shadow width (78.8 ± 10.9 μm) than eyes with mild NPDR (89.8 ± 12.1 μm, 120.9 ± 12.9 μm, 81.3 ± 15.3 μm). However, the differences were not statistically significant (p = 0.53, 0.55, 0.47). No correlation was shown between the severity of NPDR and arteriolar parameters (p = 0.31, 0.59, 0.75). Wider venular diameters were associated with increasing severity of NPDR (p<0.001, <0.001, 0.007, respectively). The association remained after multivariate adjustment for age, sex, eye, and cataract surgery (p = 0.04, 0.01, 0.007, respectively).
Conclusions: Wider retinal venule diameter was significantly associated with the severity of NPDR by SD-OCT-assisted measurement. Prospective studies would be needed to evaluate whether change in retinal venule could be used as a clinical indicator of DR progression.