Impact of Diabetic Retinopathy Lesions on Association of OCTA Metrics and Diabetic Retinopathy Severity

It remains unclear whether the distribution of lesions in the retinal periphery affects the correlation between diabetic retinopathy (DR) severity and macular vessel density. A cross-sectional, observational study sought to determine the correlation of DR lesion distribution with optical coherence tomography angiography (OCTA) metrics and disease severity.

The study took place at a tertiary care center for diabetic eye disease. A total of 225 patients (352 eyes) with type 1 or 2 diabetes underwent imaging between February 15, 2016, and December 31, 2019. The cohort was 55.6% male, and the mean age was 52.1 years. The main outcomes were OCTA vessel density in the superficial capillary plexus, intermediate capillary plexus, and deep capillary plexus and choriocapillaris flow density; DR severity and the predominantly peripheral lesions (PPLs) were evaluated using ultra-widefield color imaging.

Among the 352 eyes, 183 (52%) had mild non-proliferative DR (NPDR), 71 (20.2%) had moderate NPDR, and 98 (27.8%) had severe NPDR or proliferative DR (PDR).

Among the 209 eyes (59.4%) with no PPL, decreases were observed with increasing DR severity in the mean (standard deviation [SD]) vessel density in the superficial capillary plexus (mild NPDR, 38.1% [4.7%]; moderate NPDR, 36.4% [4.6%]; severe NPDR or PDR, 34.1% [4.1%]; P<0.001), the deep capillary plexus (mild NPDR, 45.8% [3.0%]; moderate NPDR, 45.8% [2.2%]; severe NPDR or PDR, 44.5% [1.9%]; P=0.002), and choriocapillaris flow density (mild NPDR, 69.7% [6.2%]; moderate NPDR, 67.6% [5.6%]; severe NPDR or PDR, 67.1% [5.6%]; P=0.01). When adjusting for age, signal strength index, spherical equivalent, diabetes duration and type, and correlation between eyes of the same patient, the outcomes still persisted.

Among the 143 eyes (40.6%) with PPL, increasing DR severity was not impacted by mean (SD) vessel density in the superficial capillary plexus (mild NPDR, 34.1% [4.1%]; moderate NPDR, 35.2% [4.1%]; severe NPDR or PDR, 36.0% [4.3%]; P=0.42), deep capillary plexus (mild NPDR, 44.5% [1.7%]; moderate NPDR, 45.4% [1.4%]; severe NPDR or PDR, 44.9% [1.5%]; P=0.81), or choriocapillaris flow density (mild NPDR, 67.1% [5.6%]; moderate NPDR, 69.3% [4.6%]; severe NPDR or PDR, 68.3% [5.6%]; P=0.49).

“If DR onset and worsening are associated with the location of retinal non-perfusion, assessment of global retinal nonperfusion using widefield angiography may improve the ability to evaluate DR severity and risk of DR worsening over time,” the study authors concluded.