Controlled drainage of subretinal fluid during scleral buckling surgery for rhegmatogenous retinal detachment: the pigment stream sign

Purpose To describe the macroscopic characteristics of the subretinal fluid (SRF) and its spilling modality during evacuative puncture in scleral buckling (SB) surgery for rhegmatogenous retinal detachment. Methods We retrospective reviewed all the SB surgeries performed over a period of 26 months at the University Eye Clinic of Trieste, Italy. We selected a cohort of 102 patients in which SRF drainage by means of evacuative puncture was performed. A highdefinition video was recorded during the whole duration of the procedures, and the macroscopic characteristics of the SRF leakage were assessed. Results Pigmented dark-brownish deposits spilling in the fluid outcoming from the evacuative puncture was observed during the surgeries. In all cases, this macroscopic feature was detected during the late phases of the drainage. Moreover, indirect ophthalmoscopic evaluation showed the almost complete SRF drainage and a flattened retina at that moment. Conclusions The pigment stream sign, easily detectable by the surgeon, allows to understand, during the evacuative puncture, when the SRF has been drained almost completely and that the drainage procedure is therefore close to the end.