As the use of silicone oil in the treatment of complex retinal detachment becomes more frequent, an accurate assessment of ocular structures in these eyes by ultrasonic imaging is increasingly important. Because of the ultrasonic properties of silicone oil, the interpretation of ultrasound images of the silicone-filled eye is difficult. We have developed a mathematical model of ultrasound propagation in the eye. Using a computer simulation with graphic output, we have been able to make calculations concerning the interpretation and limitations of ultrasound examination in patients with intraocular silicone oil.