Purpose: To evaluate vessel density of retinal plexuses and optic nerve head (ONH) and flow of choriocapillaris to detect possible subclinical retinal microvascular changes associated with the radiologically isolated syndrome (RIS).
Methods: We analyzed 26 eyes of 26 participants diagnosed with RIS and 39 age and sex-matched healthy controls in this prospective, cross-sectional study. The superficial (SCP) and deep capillary plexus (DCP), foveal avascular zone (FAZ) parameters, and the flow area of choriocapillaris were evaluated using optical coherence tomography angiography (OCTA).
Results: Vessel density (VD) of the parafovea (p = .045) and parafoveal subregions (p = .049 for superior hemifield, p = .016 for inferior hemifield, p = .038 for superior, p = .033 for nasal, p = .042 for inferior, and p = .005 for temporal) in SCP were significantly lower in the RIS group. There was no significant difference between the groups in VD parameters of both DCP and ONH, FAZ parameters, and choriocapillaris flow area as well as thickness parameters. (p > .05 for all). ROC analysis revealed that SCP para inferior hemifield VD, SCP para superior VD, SCP para nasal VD, and SCP para temporal VD showed good ability to differentiate RIS from healthy controls (p = .023, p = .035, p = .028, and p = .008, respectively).
Conclusions: We demonstrated a decreased vessel density in the superficial parafoveal region in RIS. Hence, we propose that changes in parafoveal vessel density imply an early impairment in RIS and microvascular changes start from the vascular-rich superficial parafoveal area. Furthermore, SCP para inferior hemifield VD, SCP para superior VD, SCP para nasal VD and SCP para temporal VD parameters have a good ability to discriminate RIS from healthy controls.
Keywords: Optical coherence tomography angiography; RIS; parafoveal vessel density; radiologically isolated syndrome; superficial capillary plexus.