Purpose: Our purpose was to determine the effect of fluid-air exchange on the amount of silicone oil (SO) droplets remaining in the vitreous cavity after removal of the main body of the SO.
Methods: This was a retrospective comparative study of 56 eyes of 56 patients that had undergone vitrectomy with SO tamponade. Fluid-air exchange was performed during surgery in 30 eyes [Air Ex(+) group] and was not done in 26 eyes [Air Ex(-) group]. All of the eyes were examined by ultrasonography, and the images were converted to binarized image. The amount of residual SO droplets/vitreal area in the images was expressed as the, "silicone oil index (SOI)". The correlations between SOI and clinical findings were determined.
Results: The SOI was significantly correlated with the axial length (AL, R = 0.444, P = 0.023). The SOI in the Air Ex(+) group was significantly higher (7.4 ± 2.6%) than in the Air Ex(-) group (4.9 ± 3.4%; P = 0.004). Multiple linear regression analyses showed that the SOI was independently and significantly correlated with the AL and the Air Ex(+) group (P = 0.003, P = 0.006, respectively).
Conclusions: Fluid-air exchange during vitrectomy to remove residual SO is not effective. Our findings indicate that it may increase the amount of residual SO droplets.
Keywords: Fluid-air exchange; Proliferative vitreoretinopathy; Residual silicone oil; Retinal detachment; Silicone oil; Tamponade; Ultrasonography.