The acoustic lighthouse effect: An ultrasonic response met in eyes after vitreoretinal surgery with silicone oil
To discuss and possibly explain the ultrasonic lighthouse effect, a metaphor suggested for an artifact-like phenomenon sometimes found by B-scan in eyes having had intra-ocular perfluorocarbon and/or silicone oil injected as part of vitreoretinal surgery.
Analysis of the ultrasonic findings with a view to the specific gravities of the above injected substances. Compared to water, perfluorocarbon has a higher and silicone oil a lower gravity; they are heavy and light, respectively.
The elicited lighthouse effect may appear localized or ‘mobile’. When evoked only from specific positions on the globe, most likely it is explained by a lens-like accumulation of material trapped at the vitreous base just under the transducer. When mobile it depends on head position; there is a gravitational shift in position of the material, as evident in particular when becoming visible in the anterior chamber.
In case reports in literature slit-lamp verified anterior segment perfluorocarbon remnants have caused acoustic disturbances of a similar nature. In this study we found evidence that also silicone oil can underlie the acoustic lighthouse effect.