Effect of silicone oil on macular capillary vessel density and thickness

The present study assessed changes in macular capillary vessel density and thickness associated with ocular silicone oil tamponade (SOT) following complex vitreoretinal surgery. A total of 23 patients who underwent pars plana vitrectomy combined with intravitreal SOT were retrospectively enrolled, and a single eye was assessed in each participant. Furthermore, 20 patients who required silicone oil removal (SOR) were included. The macular capillary vessel density and the foveal avascular zone (FAZ) area were analyzed using optical coherence tomography angiography (OCTA) and retinal thickness was assessed by OCT. The results demonstrated that the macular capillary vessel density of the superficial capillary plexus (SCP) and deep capillary plexus (DCP), the FAZ area and full retinal thickness were retained at a stable level following SOT (P>0.05), and also following SOR (P>0.05). Furthermore, the parafoveal (P=0.008), superior-hemi (P=0.007), temporal (P=0.015), superior (P=0.028) and nasal (P=0.002) inner retinal thickness decreased in the SOT group, whereas the inner retinal thickness was unaltered after SOR vs. baseline (P>0.05). In conclusion, silicone oil has no significant effect on macular capillary vessel density within a 6-month period but may compress and reduce the thickness of the inner retina.