SUSPENDED SCATTERING PARTICLES IN MOTION MAY INFLUENCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY VESSEL DENSITY METRICS IN EYES WITH DIABETIC MACULAR EDEMA

To study the effect of the suspended scattering particles in motion (SSPiM) on optical coherence tomography angiography (OCTA) vessel density metrics in eyes with diabetic macular edema (DME).Thirty-four eyes with DME from 27 patients (16 men and 11 women; 61.4 ± 9.6 years) with DME were included in this retrospective cohort study. Among these eyes, 19 (55.9%) showed the SSPiM artifact on OCTA. All participants received 3-mm and 6-mm optical coherence tomography angiography (OCTA) imaging. Perfusion density and skeletonized vessel density were calculated for the superficial capillary plexus (SCP) and the deep capillary plexus (DCP), and these were compared between eyes with and without SSPiM. Additionally, foveal vessel density in a 300-µm-wide region around the foveal avascular zone (FVD) was evaluated on 3-mm OCTA scans. The main outcome measures were vessel density in the SCP and the DCP.Among the 3-mm OCTA images, there was no statistically significant difference in SCP vessel density in eyes with and without SSPiM (P = 0.98). Vessel density in the DCP (P = 0.001 and P = 0.028 for perfusion and skeletonized vessel density, respectively) and FVD (P = 0.03) on 3-mm OCTA scans were significantly higher in DME eyes with SSPiM than in those without SSPiM. There were no statistically significant differences in vessel density in SCP and DCP between eyes with and without SSPiM based on 6-mm OCTA scans.The presence of SSPiM may lead to an overestimation of DCP vessel density in eyes with DME when 3-mm OCTA scans are used for analysis.