Development and Characterization of a Benchtop Corneal Puncture Injury Model

Abstract

During recent military operations, eye-related injuries have risen in frequency due to increased use of explosive weaponry which often result in corneal puncture injuries. these have one of the poorest visual outcomes for wounded soldiers, often resulting in blindness due to the large variations in injury shape, size, and severity. As a result, improved therapeutics are needed which can stabilize the injury site and promote wound healing. Unfortunately, current corneal puncture injury models are not capable of producing irregularly shaped, large, high-speed injuries as seen on the battlefield, making relevant therapeutic development challenging. Here, we present a benchtop corneal puncture injury model for use with enucleated eyes that utilizes a high-speed solenoid device suitable for creating militaryrelevant injuries. We first established system baselines and ocular performance metrics, standardizing the different aspects of the benchtop model to ensure consistent results and properly account for tissue variability. The benchtop model was evaluated with corneal puncture injury objects up to 4.2 mm in diameter which generated intraocular pressure levels exceeding 1500 mmHg. Overall, the created benchtop model provides an initial platform for better characterizing corneal puncture injuries as seen in a military relevant clinical setting and a realistic approach for assessing potential therapeutics. Eye-related injuries have risen in recent combat operations due to increased use of explosive weaponry. From World War I to Operations Iraqi and Enduring Freedom, eye-related injuries increased from 2% to 13% of combat injuries, respectively 1. The most prevalent ocular injuries are corneal abrasions, lacerations, and full thickness punctures, resulting in vision impairment without timely intervention 2. While there are treatments readily available for superficial corneal damage, more severe injuries such as full-thickness corneal punctures (CP) are challenging to treat. CP wounds predominantly enter through the cornea and may damage the iris, lens, and even retina, depending on the speed, material, and trajectory of how the eye was punctured 3. These injuries are not mitigated until injured warfighters are evacuated back to an ophthalmic specialist for surgical repair. For CP injuries where intraocular foreign bodies are present, the average time between point of injury and surgical repair was 21 days in recent combat operations 4. An open, untreated CP injury is highly susceptible to infection, metallic poisoning, and reduced intraocular pressure (IOP). Further, low IOP results in poor nutrient delivery throughout the eye, impacting viability and function of ocular tissues 3,5,6. As a result, CP injuries result in poor visual outcomes even after medical intervention 7. To date, when CP injuries occur on the battlefield the chain of treatment first involves placing a rigid eye shield on the injury site until evaluation by an ophthalmic specialist. If no intraocular foreign body (IOFB) is present, sutures are the gold...

An Open‐Globe Porcine Injury Platform for Assessing Therapeutics and Characterizing Biological Effects

“…The benchtop OG injury platform creates injuries using a high-speed solenoid device (Snider et al, 2020). Whole porcine eyes are used, and the extraorbital connective tissue around the eye is mimicked by placing the eye in a gelatin hydrogel solution, which more accurately mimics the OG injury mechanics compared to using a rigid eye holder (Weaver, Kennedy, Duma, & Stitzel, 2011;Weidenthal & Schepens, 1966).…”

“…The parts list below, along with the provided images and diagrams of the system, can be used to construct the puncture system used in our published work (Snider et al, 2020) and in ongoing research at the United States Army Institute of Surgical Research. The platform can be modified, however, for integration with pre-existing data acquisition setups, and different computer programs can also be utilized.…”

“…We have found that system compliance (measured in steps 1-8) is negligible compared to ocular compliance and can be neglected during these calculations (Snider et al, 2020).…”

“…However, it is challenging to develop therapeutics for this injury type, as standardized methods for injury evaluation are unlike those for other ocular traumas due to their unique shapes, sizes, and placements. To address this need in the field, we have developed, standardized, and characterized a high-speed OG injury platform (Snider et al, 2020). Our OG injury model uses enucleated porcine tissue, provides tunable injury shapes and sizes, and is compatible with a variety of different toxic or inert material types for mimicking different injury conditions.…”

“…Valves identified as #1 and #2 are called out in the protocol. Further details behind the construction of the pressure measurement system and puncture device are described in Alternate Protocols 1 and 2.Figure adaptedfromSnider et al (2020).…”