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Eric J Snider, Jorge Acevedo, Peter Edsall, Brian Lund, David O Zamora; An Ex Vivo Corneal Puncture Model for Assessing Temporary Biomaterial Therapeutics. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4683.
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Eye-related injuries have risen in recent combat operations, with corneal puncture (CP) injuries having one of the poorest visual outcomes for wounded Soldiers. We hypothesize that further damage to the eye and vision complications may be minimized if a temporary sealant can stabilize the CP site until permanent treatment can be reached (average of 21 days). Different biomaterials are being considered but a CP injury model is needed. Here, we describe a benchtop model for creating CP injures in explanted porcine eyes, a first step towards developing temporary biomaterial therapeutics for CP injuries.
The CP model uses a high-speed solenoid device (MurCal, USA). The anterior chamber of porcine eyes (Animal Technologies, USA) is connected by needle to an outer pressure transducer (40cm from eye, AD Instruments, Australia), syringe pump, and hydrostatic reservoir so that intraocular pressure (IOP) and volume can be modulated. A second catheter-style pressure transducer (Millar, USA) is drawn into the vitreous chamber. The CP model was standardized by testing different eye holders, puncture travel distances, transducer locations, and tissue preservation conditions (fresh vs. 1-7days at 4, -20, -80oC).
We found that securing eyes in 10% gelatin resulted in more consistent CP injuries compared to rigid or firmer substrates. The CP device, which travels at 90 cm/s prior to CP, was suitable for puncturing eyes at a 1.6cm travel distance. Next, ocular compliance in fresh porcine eyes was significantly different from all preservation conditions. Lastly, we compared IOP readings taken inside the eye with readings taken outside the eye. CP experiments resulted in IOP changes of 126 mmHg for outside readings while inside readings reached 1,118 mmHg.
The developed CP model is capable of reliably performing CP injuries if key aspects of the model are properly controlled. We found that it is essential to use fresh porcine tissue. Further, utilizing a gelatin eye holder allowed for more repeatable CP results. Pressure transducer location resulted in dramatically different IOP readings, presumably due to the rapid CP injury time and large distance between the outer pressure transducer and eye. Assessing each of these parameters allows the puncture process to be standardized, essential for future studies assessing potential biomaterial therapeutics.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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