Quantitative signs on ultrasound biomicroscopy images associated with the status of silicone oil emulsification within the eye.

Objectives: Silicone oil (SO) is a commonly used intraocular tamponade in the treatment of rhegmatogenous retinal detachment (RRD). SO emulsification is a common complication after SO injection. This study aimed to investigate correlations between SO emulsification signs on ultrasound biomicroscopy (UBM) and the real number/size of SO droplets.

Methods: An observational, cross-sectional study. Thirty-five RRD patients (19 males; 35 eyes) who underwent pars plana vitrectomy and SO injection were enrolled in the study. SO emulsification signs on UBM (endothelial deposits, floating droplets, ghost images, hyperoleon, anterior chamber angle impregnation, anterior iris surface impregnation, posterior iris surface impregnation and ciliary body impregnation) were acquired and quantified two days before SO removal, while real number/size of the SO droplets with a diameter in 0.4-20 μm in the first 2 mL washout fluid collected intraoperatively during SO removal were assessed by Coulter counter. Then the correlations between these values were explored.

Results: The grade of tissue impregnation and hyperoleon area in the anterior chamber demonstrated significant correlations with the number of large (5-20 μm) SO droplets ( = 0.336;  = 0.048 and  = 0.350;  = 0.039, respectively); however, no significant correlations were observed with the total number of droplets (0.4-20 μm)or the number of small (0.4-5 μm) droplets (both  ＞ 0.05).

Conclusion: The UBM quantitative grade of tissue impregnation and hyperoleon area in the anterior chamber could provide a noninvasive overview of the actual degree of SO emulsification before SO removal surgery.