Predominantly Peripheral Lesions May Foretell Severity of Diabetic Retinopathy

If patients with diabetic retinopathy (DR) do not have predominantly peripheral lesions (PPL), and their optical coherence tomography angiography (OCT-A) scans show decreasing vessel density (VD), their DR is more likely to become severe, a JAMA Ophthalmology study shows. This is not the case for patients with PPL, the researchers note. 

“These findings suggest a potential need to stratify future OCT-A studies of eyes with DR by the presence or absence of PPL,” the study says. The researchers also recommend that “if DR onset and worsening are associated with the location of retinal nonperfusion, assessment of global retinal nonperfusion using widefield angiography may improve the ability to evaluate DR severity and risk of DR worsening over time.”

The researchers evaluated 352 eyes of 225 patients (125 were male with a mean age of 52.1 years), of which 183 eyes (52.0%) had mild nonproliferative diabetic retinopathy (NPDR), 71 eyes (20.2%) had moderate NPDR, and 98 (27.8%) had severe NPDR or proliferative diabetic retinopathy (PDR). They used OCT-A and ultra-widefield (UWF) color imaging to evaluate VD in the patients’ superficial capillary plexus, intermediate capillary plexus, and deep capillary plexus; choriocapillaris flow density, and severity of DR and PPL.

Their research shows that, in eyes with no PPL (59.4%), the mean VD in the superficial capillary plexus and the deep capillary plexus, as well as the mean choriocapillaris flow density, decreased with increasing DR severity. 

However, in eyes with PPL (40.6%), mean VD in the superficial capillary plexus and the deep capillary plexus as well as the mean choriocapillaris flow density did not appear to change with increasing DR severity.

All the associations remained statistically significant even after taking into account the participants’ varying ages, signal strength index, spherical equivalents, duration of diabetes, type of diabetes, and correlation between eyes of the same patient. 

While prior research has shown associations between decreasing OCT-A VD and worsening DR severity, none of it took PPL into account. This study distinguishes that it found no association between central VD and DR severity in eyes with PPL. Approximately 37% to 41% of patients with DR present with PPL.

The JAMA study’s findings appear to be consistent with the view that “worsening DR severity in an individual eye may be associated primarily with either central or peripheral nonperfusion,” the researchers explain.

The investigators advocate for ophthalmologists to both stratify analyses based on the  presence or absence of PPL and to apply UWF angiography for global retinal nonperfusion assessment in cases when DR onset and worsening are associated with the location of the nonperfusion.

Reference

Ashraf M, Sampani K, Rageh A, Silva P, Aiello L, Sun J. Interaction between the distribution of diabetic retinopathy lesions and the association of optical coherence tomography angiography scans with diabetic retinopathy severity. JAMA Ophthalmol. Published online October 29, 2020. doi: 10.1001/jamaophthalmol.2020.4516