The longitudinal follow-up of a newly proposed OCTA imaging finding (SSPiM) and the importance of it as a new biomarker for treatment response in diabetic macular edema

Abstract

Purpose This study aimed to evaluate the frequency of SSPiM (suspended scattering particles in motion), systemic risk factors, ocular findings, progression characteristics, and treatment response in diabetic retinopathy (DR) patients. Methods In this prospective study, a total of 109 eyes of 109 patients with diabetic macular edema (DME) were included. Demographic characteristics and systemic data of the patients were recorded. In addition to a detailed ophthalmological examination, optical coherence tomography (OCT) and OCT angiography (OCTA) imaging were performed. According to the OCTA images, the patients were divided into two categories: SSPiM detected (SSPiM +) and undetected (SSPiM −). The patients were followed up at 0, 3, and 6 months. Treatment responses at 6 months in treatment-administered patients with and without SSPiM were examined. Results The frequency of SSPiM in DME cases was found to be 34.9%. No significant correlation was found between SSPiM and demographic characteristics, systemic, and biochemical parameters (p > 0.05). It was observed that SSPIM was most frequently localized in the outer nuclear layer adjacent to the outer plexiform (81.6%). SSPiM appearance disappeared in 7 (19.4%) of 36 patients with SSPiM who had regular follow-up for 6 months. In 4 (11.1%) of these seven patients, hard exudate plaques developed in the areas where SSPiM disappeared. Regarding treatment response at 6 months, the decrease in CMT was statistically significantly lower in the SSPiM group compared to cases without SSPiM. Conclusion SSPiM is a finding seen in approximately one-third of DME patients and may adversely affect the response to the treatment.