Dynamic biological macular vascular changes of silicon oil tamponade in patients with rhegmatogenous retinal detachment

Pars Plana Vitrectomy (PPV), combined with intravitreal tamponade Silicone Oil (SO), is one of the most popular and effective surgical interventions for Rhegmatogenous Retinal Detachment (RRD), achieving high rates of anatomic reattachment. However, long-term SO Tamponade (SOT) can induce structural and microcirculation alterations, affecting visual function, even after SO Removal (SOR). Therefore, for an appropriate SO Filling (SOF) duration, we investigated the dynamic changes of macular vasculature during SOF and after SOR. 51 eyes (51 patients) with macular-on RRD underwent single PPV and were randomly divided into 2 groups according to intravitreal SOT duration, either for 2 or 3 months. Optical Coherence Tomography (OCT) and angiography were used to evaluate the macular perfusion system, which was segmented into Superficial and Deep Capillary Plexus Flow Density (SCPFD, DCPFD) and Choriocapillaris Plexus Flow Density (CCPFD). The VA (VA) and the flow density were measured at 1 week, 1 month, 2 months, and 3 months SOF, and 1 week and 1 month post SOR. Both 2- and 3-month SOT strongly reduced VA, particularly in the first month. There was no significant difference in VA between the two groups during the opinion. Compared with that before the surgery, the VA had a 51% reduction after 2 months and a 57% reduction after 3 months of SOF, which was not recovered even after a 1-month SOR. 2-month SOT did not significantly affect macular microvascular. However, SCPED was starkly suppressed at 3-month SOF, following a significant increase after 1-month SOR. Moreover, 2-month SOT caused slight changes in macular microcirculation during the observation, together with a fast recovery of VA after 1-week SOR, about 90% of VA at 1-week SO. However, the flow densities in all three segmented layers upon 3-month SOT were correlated with each other, showing the same fluctuation trend, i.e., strong suppression at 3-month SO and slow recovery after SOR, which a low VA accompanied after 1-week SOR, about 50% of VA at 1-week SOT. Either 2- or 3-month SOT reduced VA of RRD eyes. However, unlike 2-month SOF, 3-month SOT could induce strong suppression of macular microcirculation, which might be detrimental to VA recovery of RRD eyes after PPV surgery. Therefore, a 2-month SO might be an appropriate time for SOR to achieve a better functional recovery of RRD.