Abstract
Purpose :
Ocular blast injuries result from a variety of damage mechanisms. Primary blast waves can cause damage with local increases in pressure. Secondary injuries from projectiles can cause penetrating and blunt trauma. Current injury models study a single mechanism and do not consider possible additive effects of multifactorial damage. The goal of this study is to produce and test a repeatable and controllable combined injury model in ex vivo porcine eyes and in in vivo rabbits.
Methods :
A custom injury model device was fabricated that produces a primary blast wave, secondary corneal puncture injury, and blunt trauma in a simultaneous event. The physical effects of pressure, blade length, and blunt force were measured or calculated with a pressure transducer, microscopy, and projectile velocity, respectively. Immediate pathological effects were measured on fresh, intact porcine eyes, which were obtained from a local slaughterhouse. Blade lengths of 200, 400, and 600 µm were tested. Porcine corneas were analyzed with cornea strip extensiometry and histology. The injury model was further tested in New Zealand white rabbits. Wound healing was observed with ophthalmic exams at regular intervals and with histology at days 3 and 14 following injury.
Results :
The injury device produced consistent and controllable peak pressure, blade length, and blunt force. In porcine eyes, corneal strip extensiometry showed a decrease in elastic modulus (p<0.01, ANOVA) and ultimate stress (p<0.0001, ANOVA) with increased blade length (n=6). Histology showed that the wound depth correlated with blade length. In the in vivo study, fluorescein staining in ophthalmic exams and collagen imaging in histological analysis revealed a consistent location and depth of injury. By day 3, epithelial cells migrated and proliferated in the wound, and by day 14, scar tissue was observed through alpha-smooth muscle actin staining.
Conclusions :
Our results demonstrate a novel model that combines damage mechanisms underlying blast injury. The model produces consistent and controllable damage in ex vivo porcine eyes and in in vivo rabbits. The model could be used to assess compounding effects of blast injury mechanisms and to test multipronged therapies for these injuries.
This is a 2021 ARVO Annual Meeting abstract.