Removal of Large Foreign Bodies Made of Thermoplastic Material from the Eye

Purpose To present the results of research aimed at developing a new method of minimally invasive removal of an intraocular foreign body (IOFB) from the eye cavity. Methods The main idea was to fix the IOFB onto the edge of a laser probe, which is transsclerally injected into the eye. After that, the IOFB is fixed at the end of the laser probe and removed transpupillary from the eye through an incision in the cornea. In order to fix the IOFB on the laser probe edge, this edge should be brought closely to the IOFB surface. The material of the IOFB should be locally fused using the laser emission. During this process, the probe edge should be submerged into the liquid melt. After laser emission is turned off, the material around the probe is hardened and the IOFB is hardly fixed on the laser probe edge. Results and Conclusions The main laser emission parameters and their influence on the eye tissue were investigated within a thermodynamic model. It is shown that for IOFB made from polyethylene terephthalate the optimal laser power is close to 2 W, the rate of rise of light energy is more than 10 ms, and the wavelength is approximately 0.905 μm. With these parameters (taking into account multiple scattering effects), the light impact on the retina will not exceed 100 mW/cm2, which is not dangerous for eye tissue. Efficiency is supported by clinical testing. The method was used for intraocular extraction of an Airsoft ball bearing (6 mm sphere of polyethylene terephthalate). The overall extraction time was approximately 4 minutes.