Use of Cohesive Viscoelastic Agents to Facilitate Safe Removal of Posterior Segment Intraocular Foreign Bodies.

Purpose: To assess the ability of viscoelastic agents and perfluoro-N-octane (PFO) to safely remove an intraocular foreign body (IOFB). Methods: A 23-gauge pars plana vitrectomy and lensectomy were performed in a porcine eye. A 5.0 mm metallic IOFB was inserted through a corneal paracentesis and dropped into the vitreous cavity. The posterior segment was filled completely with a balanced salt solution, cohesive viscoelastic, or dispersive viscoelastic or was partially filled with PFO under a balanced salt solution. The IOFB was then brought anteriorly and released. Each test was repeated multiple times and videorecorded. Results: The IOFB fell with high velocity through the balanced salt solution-filled vitreous cavity. When the eye was filled with either of the 2 viscoelastic agents, the IOFB did not move or moved posteriorly extremely slowly. A vitreous cavity filled partially with PFO led to deflection of the object's path, with the peripheral retina being struck, or the IOFB dropping straight down and striking the macula. PFO and the cohesive viscoelastic were easily removed from the eye with the vitrectomy instrument. The dispersive viscoelastic could not be completely removed and repeatedly clogged the vitreous cutter. Conclusions: Filling the posterior segment with a cohesive viscoelastic agent may significantly increase the safety and ease of IOFB removal.