[Evidence of silicone oil deposits via high resolution ultrasound]

Using biomicroscopy the evidence of deposits of silicone oil in the anterior segment after vitrectomy is limited. We examined the anterior segment by high resolution ultrasound to verify the possibility to identify silicone oil.

Ten patients treated by vitrectomy with instillation of silicone oil were examined by high resolution ultrasound before and after the removal of silicone oil. The duration of silicone oil tamponade was at least 5 months. A 20-MHz-sectorscanner was used for examination. We compared the findings of ultrasound and biomicroscopy with groups of patients with or without pharmacological mydriasis, blue or brown colour of the iris.

The patients treated by vitrectomy and instillation of silicone oil showed small high reflective structures at the endothelium, the anterior front of the iris and in the angle. These highly reflective structures were found more often before, less often after operative extraction of silicone oil and could not be shown in the control groups. Using biomicroscopy we could not see an equivalent to all of the highly reflective structures.

The highly reflective structures we found by ultrasound are probably inclusions in endothelial cells, silicone oil-induced calcifications or free particles of silicone oil. High resolution ultrasound with a 20-MHz-sectorscanner can be used for identifying indication and localising of silicone oil in the anterior segment even if biomicroscopic signs are absent.