Optical coherence tomography angiography (OCTA) with longer interscan times provides more accurate microaneurysm imaging in patients with diabetic retinopathy (DR), according to research published in Ophthalmology Science.

Researchers enrolled 45 eyes (9 without diabetes, 13 with no DR, 11 with nonproliferative DR, 12 with proliferative DR) of 34 patients (mean age 55.2±12.8 years, 21 men) in the analysis. The team performed comprehensive eye examinations including best-corrected visual acuity (BCVA) measurement, biomicroscopy, fundus photography, and OCTA imaging on all patients. They compared capillary flow density and visualization of retinal capillaries in the superficial and deep capillary plexuses (SCP and DCP, respectively) obtained by OCTA imaging at 3 insterscan times (4.3, 5.7, and 8.6 milliseconds (ms)). 

Investigators determined that SCP and DCP retinal flow density was not significantly different between images observed at each interscan time. The team did detect some capillaries at longer interscan times that could not be imaged at 4.3 ms. Researchers were able to detect some microaneurysms and note morphological changes with longer interscan times that the shorter 4.3 ms could not identify. The different imaging points in both the SCP and DCP were significantly higher in both patients with nonproliferative and proliferative DR than in patients without diabetes or DR (P <.01), according to the report.


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“These results indicate that in DR, there is slower blood flow that cannot be detected by OCTA in a conventional setting,” according to the researchers. “Therefore, prolonging the interscan time enables accurate detection and visualization of capillaries with slower blood flow.”

Study limitations include a small sample size, confounding due to vitrectomy or anti-vascular endothelial growth factor (anti-VEGF) treatments, and the exclusion of individuals with poor visual acuity.

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

Reference

Kaizu Y, Nakao S, Soda T, et al. Longer interscan times in optical coherence tomography angiography detect slower capillary flow in diabetic retinopathy. Ophthalmol Sci. Published online June 12, 2022. doi:10.1016/j.xops.2022.100181