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Chirag Shah, Bryce Schroeder, Mitul Mehta; Perfluorocarbon-Balanced Salt Solution Interface Deflects Intraocular Foreign Bodies. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5104.
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Perfluorocarbon liquids (PFCLs) have been previously used to float various objects off the retina, and some surgeons have begun to use PFCLs during intraocular foreign body (IOFB) extraction. The purpose of this study was to examine the utility of perfluoro-n-octane (PFO) to shield the macula from the impact of dropped metallic IOFBs by modelling scenarios in which they may fall during removal.
Model eyes were made of plastic spheres 3.5 cm in diameter. In each trial, model eyes were filled with one of several fluid mixtures (100% PFO, 100% BSS, and 10% PFO/ 90% BSS). The 10% PFO was used to cover the macula. 5 sample IOFBs (Fig 1 IOFBs A-E) were selected from metal debris of human-operated cutting tools in machine shops.<br /> IOFBs were submerged and dropped 50 times from several starting positions (center of the globe, touching the interior globe, or touching the central PFO-BSS interface). Trajectories were recorded using a camera attached to a Zeiss operating microscope. Fisher’s exact test was used to assess differences in number of trials impacting the macula between the PFO/BSS mixture and BSS alone.
All IOFBs impacted the macula in all trials using PFO or BSS alone. IOFBs A, B, & C were deflected by the PFO-BSS interface in 100% of trials (difference significant vs. BSS, p<0.0001). IOFB D was deflected in 96.7% of trials from a central position in the superior fluid (p<0.0001) as well as 100% of trials from a peripheral position (p<0.0001), but impacted the macula in 33% trials when dropped from the PFO-BSS interface (p=.0964). IOFB E impacted the macula in 100% trials from the central position (p=1.0), but was deflected by the PFO-BSS interface in 100% trials when dropped from a position touching the interior globe (p<.0001).
This study suggests that the surface tension of the PFO-BSS interface may be used to protect the macula by deflecting IOFBs dropped during surgery. The location and characteristics of the IOFB determine the amount of deflection. As seen with IOFB E, IOFBs that pierce the PFO-BSS interface when incident from a central position may be deflected if tumbling towards the interface from a position touching the interior globe, suggesting that some amount of kinetic energy is dispersed by the surface tension of the PFO-BSS interface.
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