A greater baseline choriocapillaris flow deficit percentage (CC FD%) measured by swept-source optical coherence tomography angiography (SS-OCT-A) can reliably predict the risk of referable diabetic retinopathy (RDR) in patients with type 2 diabetes mellitus, according to research published in the British Journal of Ophthalmology. The findings indicate that CC FD% may act as a novel biomarker for predicting the onset and progression of diabetic retinopathy (DR).

The researchers conducted a prospective cohort study to evaluate the association between the CC FD% and 1-year incidence of RDR in patients with type 2 diabetes mellitus.

They graded DR status based on the Early Treatment Diabetic Retinopathy Study (ETDRS)-7 protocol using a digital fundus photography and measured the CC FD% in the central area (1 mm), inner circle (1.5 to 2.5 mm), and outer circle (2.5 to 5.0 mm). They also measured the entire area in the macular region using SS-OCT-A. 


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A total of 1222 eyes of 1222 patients (58.1% women, 41.9% men; mean age, 65.1±7.4 years) participated in the study and had complete baseline and 1-year follow up data. 

The team found that each 1% increase in baseline CC FD% in the macular region was significantly associated with 1.69 times higher odds for development of RDR after 1 year of follow up (relative risk [RR], 2.69; 95% confidence interval [CI], 1.53-4.71; P =.001). 

They also found 0.78 times and 1.54 times higher odds for development of RD for each 1% increase in baseline CC FD% in the inner circle (RR, 1.78; 95% CI, 1.07-2.96; P =.026) and outer circle (RR, 2.54; 95% CI, 1.47-4.40; P=.001), respectively.

“Monitoring CC FD% could facilitate the risk stratification of the diabetic population to personalize the frequency of DR screening accordingly,” the researchers explain.

Limitations of the study included only 1 year of follow up, measurement of choroidal blood flow at a single time point without consideration of possible diurnal variation, and inclusion of only patients from Southern China.

Reference

Wang W, Cheng W, Yang S, Chen Y, Zhu Z, Huang W. Choriocapillaris flow deficit and the risk of referable diabetic retinopathy: a longitudinal SS-OCTA study Br J Ophthalmol. Published online May 16, 2022. doi:10.1136/bjophthalmol-2021-320704