Assessment of Silicone Oil Emulsification: A Comparison of Currently Applied Methods

PURPOSE: To compare ultrasound biomicroscopy (UBM), Coulter counter, and B-scan ultrasonography in the evaluation of silicone oil (SO) emulsification. METHODS: Patients who underwent primary pars plana vitrectomy with SO tamponade for rhegmatogenous retinal detachment and SO removal were included. UBM images were acquired before the SO removal, and B-scan images were taken after removal. The number of droplets in the first and last 2 mL of washout fluid was analyzed using a Coulter counter. The correlations between these measurements were analyzed. RESULTS: Thirty-four eyes received both UBM and Coulter counter analysis for the first 2 mL of washout fluid, and 34 underwent B-scan and Coulter counter analysis of the last 2 mL washout fluid. The mean UBM grading was 26.41 ± 9.71 (range: 1–36); the mean SO index obtained with B-scan was 5.25 ± 5.00% (range: 0.10–16.49%), and the mean number of SO droplets was 1.26 ± 2.45 × 10(7)/mL and 3.34 ± 4.22 × 10(6)/mL in the first and last 2 mL of washout fluid, respectively. There were significant correlations between UBM grading and SO droplets in the first 2 mL and between B-scan grading and SO droplets in the last 2 mL (all P < 0.05). CONCLUSIONS: UBM, Coulter counter, and B-scan ultrasonography could all be used in the evaluation of SO emulsification, and their findings were comparable.