Severe diabetic macular edema (DME) is associated with poor visual acuity, increased irregularity in the foveal avascular zone (FAZ), and vascular rarefaction in the deep vascular plexus (DVP), according to a study published in Eye and Vision

Investigators recruited 74 patients (92 eyes) with DME from a single center between June 2019 and September 2021 (mean age 56.23±12.35 years, 68.92% men, mean duration of diabetes mellitus 13.13±7.67 years). They stratified eyes with DME into 1 of 3 groups based on severity: early (n=24), advanced (n=53), and severe (n=15). The team calculated vessel density (VD) in the superficial vascular plexus (SVP) and DVP, and obtained FAZ parameters including FAZ area, FAZ perimeter, acircularity index, and foveal VD in a 300-μm-wide region around the FAZ (FD-300). They assessed associations between visual acuity and optical coherence tomography angiography (OCTA) metrics. 

According to the report, 93.24% of participants had type 2 diabetes, 58.11% had hypertension, 44.59% had a diagnosis of hyperlipidemia, and 37.84% had a history of renal impairment. Of the 92 eyes included in the study, 52 had non-proliferative diabetic retinopathy and 40 had proliferative diabetic retinopathy. 


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The researchers found that acircularity index was higher in eyes with severe DME compared with early (P =.006) and advanced DME (P =.003). In patients with severe DME, the whole and parafoveal VD in the DVP demonstrated more diffuse vascular rarefaction than in early DME (P =.018 and P =.005, respectively) and advanced DME (P =.035 and P =.012, respectively). The team determined that DME severity, FAZ area, and foveal thickness were positively associated with worse visual acuity (P =.001, P =.007, and P =.001, respectively). 

“Greater severity level of DME, larger FAZ area, and increased foveal thickness could be risk factors for poor visual acuity,” according to the researchers. “OCTA could be a promising device for evaluating DME severity and visual acuity.” 

Study limitations include a cross-sectional design, the relatively small sample size of patients, and an uneven distribution of patients according to DME severity. 

Reference

Han R, Gong R, Liu W, Xu G. Optical coherence tomography angiography metrics in different stages of diabetic macular edema. Eye and Vis. Published online April 5, 2022. doi:10.1186/s40662-022-00286-2