Ultrasound biomicroscopy assessment of the subclinical involvement of the aqueous drainage structures after silicone oil tamponade.

Purpose: To examine the subclinical ultrasound biomicroscopy (UBM) changes in the anterior segment (AS) of eyes after silicone oil tamponade (SOT) permanence.

Methods: This observational study enrolled patients undergone pars plana vitrectomy for retinal detachment with SOT. UBM was performed shortly before removing the SOT from eyes without any clinically detectable emulsion/particle in the AS (i.e., the study cohort). For each subject, four radial scans of the AS were obtained circumferentially for both the study and the fellow non-operated eye (i.e., the control cohort). A region of interest (ROI) was identified in each UBM scan and the maximum, minimum, and mean echo-reflectivity were assessed using imageJ software.

Results: The study enrolled 33 patients (66 eyes). Of the study eyes, 15 underwent high-density tamponade (SOX), 11 underwent 2000cSt tamponade (SO2), and seven underwent 5000cSt tamponade (SO5). Significantly higher echo-reflectivity was detected in the superior quadrants of groups SO2 and SO5 (P = 0.04 and 0.02, respectively) and in the inferior quadrant of group SOX (P < 0.01) compared to the corresponding control eyes. In group SO2, the duration of the intraocular tamponade positively correlated with the number of hyper-reflective quadrants (P < 0.01).

Conclusions: The significant relationship between SOT density and the localization of areas of increased echo-reflectivity supports the actual relationship between SOT trabecular impregnation and UBM findings, even in eyes free from visible emulsions. In the SO2 group, the duration of the intraocular SOT correlated with the extent of the involvement of the filtering structures.