Intraretinal Microvascular Abnormalities May Reveal Retinal Nonperfusion in DR

Intraretinal microvascular abnormalities, which may be detected using a multimodal imaging approach consisting of ultrawidefield-color fundus (UWF-CF) and widefield-optical coherence tomography-angiography (WF-OCT-A) imaging, may indicate underlying retinal ischemia in individuals with diabetic retinopathy (DR), according to an investigation published in Ophthalmology Retina. 

Researchers included 50 patients (eyes, 75; mean age, 53.3 years; 76% men) with varying stages of DR, according to Early Treatment Diabetic Retinopathy Study (ETDRS) criteria, in the prospective, cross-sectional investigation. The team determined the presence of predominantly peripheral lesions using UWF-CF and created a custom grid to subdivide retinal areas visible on WF-OCT-A assessment. The team measured retinal nonperfusion in each of these subdivided areas, calculated nonperfusion index, and determined the number of hemorrhages, neovascularizations, and areas with intraretinal microvascular abnormalities.  

Median retinal nonperfusion area was 5.4 mm² and median retinal nonperfusion index was 2%. Overall retinal nonperfusion and nonperfusion index were significantly correlated with ETDRS classification (P <.01). The location of retinal nonperfusion varied depending on DR stage. The inferior fields were most affected in moderate disease stage, while superior fields were most affected in severe disease stage, according to the report.

Among the cohort, 21% of eyes had mild DR, 23% had moderate DR, 30% had severe non proliferative DR (NPDR), and 27% had severe proliferative DR (PDR). A total of 79% of eyes demonstrated retinal nonperfusion, and eyes without retinal nonperfusion either had mild (n=14) or moderate (n=2) DR.

The team observed significant correlations between the number of microaneurysms and hemorrhages with retinal nonperfusion, with the highest correlation observed between the number of subfields affected by intraretinal microvascular abnormalities with retinal nonperfusion and nonperfusion index. 

“[A] multimodal imaging approach using WF-OCTA and UWF-CF allows precise analysis of microvascular DR features including the presence of [retinal nonperfusion] with [intraretinal microvascular abnormalities] and [predominantly peripheral lesions] on CF images potentially being indicators for the extent of underlying retinal ischemia,” the researchers explain. “The combination of WF-OCTA and UWF-CF may [prove] to be the primary imaging tools for clinical assessment of DR in eyes with adequate image quality.”

Study limitations include the exclusion of a large percentage of images due to poor quality (36%) and the use of a WF-OCT-A prototype with a field of view smaller than those used in commercial ultrawidefield devices. 

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.