ANTERIOR-CHAMBER METAL FRAGMENTS AFTER PHACOEMULSIFICATION SURGERY

Purpose: To determine whether metal fragments can be shaken loose from phaco needles during surgery and embed in the iris. Setting: Private practice, Vernon, British Columbia, Canada, and scanning electron micr oscope laboratory, Master Precision, Rapid City, South Dakota, USA. Me thods: The surfaces and rims of new and used phaco needles and the lum ens of halved new needles were examined by scanning electron microscop y (SEM). To determine whether the fragments on the phaco needles were approximately the same size as those seen in the iris, a photograph of an eye with metal fragments imbedded in the iris was projected and th e image size of the metal fragments approximated by using their magnif ication value. The magnification scale of the SEM images was used to d etermine the size of the metal fragments photographed on the phaco nee dles. Results: The SEM studies of new phaco needles revealed tiny frag ments of metal firmly adherent to the interior, exterior, and rim surf aces. No fragments were detected on the surfaces of the used phaco nee dles. Two metal fragments in the eye photograph were calculated to be 0.20 x 0.20 mm and 0.15 x 0.20 mm. Those in the SEM photos were calcul ated to be 0.03 to 0.10 mm. Conclusion: Although SEM of new titanium p haco needles revealed adherent metal fragments on their lathed surface s, no fragments were found on used phaco needles. The iris fragments c alculated from a projected photograph were slightly larger than those from the SEM micrographs, supporting the conclusion that annealed meta l fragments shook loose from the phaco needles. This indicates that ul trasonic activation of a new phaco needle with metal fragments anneale d to its surface causes fragments to release and embed in the iris.