Low-cost electromagnet for extraction of metallic intraocular foreign body
Joselito Joel R. Castro Jr., MD, Rodolfo U. Chuanico, MD, FACS
Objective
To develop a low-cost electromagnet for extraction of metallic intraocular foreign body.
Methods
This is an experimental study of an improvised electromagnetic device for extraction of intraocular metallic foreign body in a porcine eye. The device is an electromagnet made from locally available electronic materials. It is equipped with two sizes of solenoid coil heads acting as the reservoir of magnetic field. The coils are fitted with two types of probes for intraocular and external magnetic extraction in a porcine eye. The device is compared with a rare earth permanent magnet to demonstrate its strength over existing magnets used in ophthalmology. The strength of the device is quantified by magnetizing a series of weighted iron plates and determining the maximum weight it held. The porcine eye was cut and the anterior hyaloid phase preserved. A 6 x 5- millimeter metallic fragment was introduced intravitreally; magnetic extraction was done with the use of the electromagnetic device through a 3mm sclerostomy.
Results
The device is 100 times less expensive than its commercial counterpart and stronger than the permanent magnet. It has a maximum lifting capacity of 8.5 pounds. The electromagnetic probe extracted the 6 x 5 mm metallic fragment from the porcine eye.
Conclusion
The low-cost electromagnet has a potential use in internal and external extraction of metallic intraocular foreign bodies in human patients.