The nature and origin of intraocular metallic foreign bodies appearing after phacoemulsification

In order to evaluate the nature and origin of metallic foreign bodies embedded in the iris after uneventful phacoemulsification, we aimed to produce metallic fragments by applying ultrasound power with the same phaco machine and handpiece in an experimental model in vitro. In a glass bottle, we used linear phaco power of 100% continuously for 5 min first with a new phaco tip and then with a used tip. Afterwards, the fluid in the bottle was filtered through a Millipore filter. The remains on the filter were studied by scanning electron microscopy (SEM) and microprobe. Small particles remained on the filter which was used for the new tip. Microprobe microanalysis showed that these particles were mainly titanium, the same as the phaco tip. SEM of both the new and the used tips showed small fragments on the exterior surface and lumen. Intraocular metallic foreign bodies after phacoemulsification are likely to be shaken loose from the phaco tip. Although it is mostly agreed that these fragments are well tolerated, their overall effect remains to be evaluated in the long term.