Retinal vasculature-function correlation in non-proliferative diabetic retinopathy.

PURPOSE

To compare and correlate retinal microcirculation and function in patients with non-proliferative diabetic retinopathy (NPDR).

METHODS

Thirty-three healthy controls (33 eyes), 36 diabetic patients with no clinically detectable retinopathy (NDR, 36 eyes) and 101 patients (101 eyes) with NPDR (35 mild NPDR, 34 moderate NPDR, 32 severe NPDR) were involved in the study. We used optical coherence tomography angiography (OCTA) to quantify the macular vessel density (VD) of superficial capillary plexus (SCP), deep capillary plexus (DCP) and foveal density in a 300 μm region around foveal avascular zone. Retinal function was assessed by a mydriasis-free, full-field flicker electroretinogram (FERG) recording device, and the amplitudes and implicit time were recorded. The association between microvascular parameters and FERG results was analyzed with stepwise multiple linear regression model.

RESULTS

Decreased amplitudes and delayed implicit time, as well as lower parafoveal/perifoveal VD in both SCP and DCP, were found in NDR group and NPDR groups compared with the control group (all p < 0.05). Specifically, the FERG parameters and microvascular indices were comparable between NDR group and mild NPDR group (all p > 0.05). However, compared to mild NPDR, the reduction in FERG amplitude was more pronounced than the reduction in parafoveal VD (both SCP and DCP) in severe NPDR. Stepwise multiple linear regression analyses showed that delayed implicit time was significantly correlated with increased age and decreased VD of parafoveal region in both SCP and DCP in patients with NPDR. Meanwhile, decreased amplitude was significantly associated with decreased VD of parafoveal region in both SCP and DCP in patients with NPDR.

CONCLUSION

Macular VD in both superficial and deep capillary plexus correlated with ERG implicit time and amplitude in mild-to-severe NPDR. OCTA and FERG may both be useful in detection of preclinical DR and early DR, but once the disease deteriorates, FERG may be more sensitive to discern progression of DR.