Progression of Diabetic Retinopathy, Not Development, Measurable With OCT-A

Optical coherence tomography angiography (OCT-A) measures diabetic retinopathy (DR) progression parameters, such as baseline vessel density (VD) and macular perfusion (MP) of the superficial capillary plexus, in patients with type 2 diabetes mellitus, according to a study published in Eye. However, the imaging technology is not able to successfully anticipate the development of diabetic retinopathy, according to the report.

The study reviewed 206 eyes of 219 patients with diabetes (mean age, 58.4±9.1 years; mean diabetes duration, 11.3±7.1 years). At baseline, 177 patients had no DR and 99 had mild or moderate nonproliferative diabetic retinopathy (NPDR)a. Of the 161 eyes with no DR that underwent final follow up, 27 developed incident disease. In 45 eyes that started out with NPDR, 17 progressed.

Patients who eventually experienced progression of diabetic retinopathy presented an average baseline VD of 12.90 mm/mm², significantly lower than 14.90 mm/mm² of stable eyes (P =.032). Analysis for hazard ratio (HR) revealed the odds for DR worsening rose by 1.21 times per unit (mm/mm²) of lower vascular density.

Also, patients with a mean MP of 36.96% did not progress, but those at 31.79% worsened (P =.043); showing progression risk of 1.10-fold per unit (percent) reduction. Researchers set sensitivity at approximately 80% to minimize false negatives. A cut-off of 15.85 mm/mm² VD yielded 77.4% sensitivity and 41.8% specificity for predictive ability; and a 40.75% MP benchmark offered 77.4% sensitivity, and 25.5% specificity.

“Progression of DR occurred in 37% of eyes with NPDR and was associated with a lower baseline OCTA-derived vascular density and macular perfusion, with no difference in OCT-derived RNFL and GCL-IPL thicknesses,” the researchers explained.

Previous studies using OCT-A to assess microvasculature of eyes for incidence and stage of DR found a relationship with increased foveal avascular zone (FAZ) and lower VD. Further, FAZ area and fractal dimension are reported to be linked to worsening DR.

A sample comprising few with severe NPDR or proliferative DR limited this analysis, as well as no automated measure available to test the deep capillary plexus. Alternatively, a strength included use of ultra-wide field fundus photography to detect and characterize DR severity.