Early detection of retinopathy in patients with diabetes is key; by the time visual impairment occurs, the retinal microvasculature has already been damaged. The introduction of OCT-A presented an opportunity to visualize retinal structures in more detail and better detect diabetic macular ischemia, but to date, most studies have only included adults with type 2 diabetes. A recent study, however, applied OCT-A to younger patients with type 1 diabetes and found that the tool can detect the earliest signs of nonproliferative diabetic retinopathy (NPDR) before the condition is visible with ophthalmoscopy.
The cross-sectional Norwegian study included 315 eyes of individuals aged 14 to 30, with at least a 10-year history of type 1 diabetes, and 168 control eyes. The researchers found that lower vessel density in the deep capillary plexus, longer diabetes duration and higher waist circumference were significantly associated with NPDR progression. Compared with controls, patients with type 1 diabetes who didn’t have diabetic retinopathy had a significantly lower vessel density in the superficial and deep capillary plexuses. Vessel density, however, was not associated with visual acuity.
Additionally, they noted that vessel density in macular plexuses can better discriminate between patients with and without type 1 diabetes compared with foveal avascular zone area, total retinal volume and central macular thickness. This indicates that vascular pathology precedes thinning of the central macular area.
The researchers concluded that vessel density in the deep capillary plexus is one of the best noninvasive biomarkers of early diabetic retinopathy and is able to discriminate between stages of NPDR. They emphasized that foveal avascular zone area measured by OCT-A was not a good predictor of diabetic retinopathy. “OCT-A is a much more sensitive tool to diagnose early NPDR than conventional OCT and funduscopic ICDR grading,” the study authors concluded in their paper.
Veiby N, Simeunovic A, Heier M, et al. Associations between macular OCT angiography and nonproliferative diabetic retinopathy in young patients with type 1 diabetes mellitus. J Diabetes Res. November 30, 2020. [Epub ahead of print].