[An analysis of intraocular metallic foreign body injury during hammer percussion]

Objective: To investigate the cause of intraocular metallic foreign body injury during hammer percussion and to observe the structure of the metallic foreign bodies. Methods: A retrospective analysis was performed in 21 inpatients with metallic foreign body injury in the posterior segment from January 2013 to April 2016. The foreign bodies were removed by magnetic drawing through external route of the sclera or vitrectomy. The shape of the foreign bodies was analyzed and the structural characteristics were observed under a metallurgical microscope. The visual acuity of the patients was compared before and after treatment. Results: All patients were discharged at one week after surgery. There was no significant difference in mean best corrected visual acuity of the patients between before treatment and after treatment (1.20±0.87 vs. 1.08±0.89, t=1.516, P>0.05). The metallic foreign bodies in all the 21 cases were magnetic and the injuries in 15 cases (71.43%) were caused by hammering on hard objects. The foreign bodies were mainly lamellar and shaped like a leaf or a lance. And the lamellar martensite structure was observed under a metallurgical microscope. Conclusion: The intraocular metallic foreign body injury often occurs during hammer percussion and the microstructure of the foreign bodies is lamellar martensite structure.