Blunt eye trauma: empirical histopathologic paintball impact thresholds in fresh mounted porcine eyes.

PURPOSE Ballistic studies were conducted using gelatin-embedded abattoir-fresh porcine eyes suspended within clear acrylic orbits to discern the energy required to produce specific ocular injuries. Paintball impact provides a robust ballistic model for isolating and quantifying the role of direct blunt force in ocular trauma. METHODS Fifty-nine porcine orbital preparations received direct blows from 0.68 caliber (16-18 mm diameter/3.8 g) paintballs fired at impact velocities ranging from 26 to 97 meters per second (2-13.5 J). Five additional eyes not subjected to ballistic impact were also evaluated as controls. Impact energies were correlated with histopathologic damage. RESULTS Minimum impact energies consistently producing damage in experimental eyes unobserved in control specimens were: 2 joules--posterior lens dislocation, zonulysis, capsular rupture, and choroidal detachment; 3.5 joules--moderate angle recession; 4 joules--anterior lens dislocation; 4.8 joules--peripapillary retinal detachment; 7 joules--severe angle recession, iridodialysis, and cyclodialysis; 7.5 joules--corneal stromal distraction; 9.3 joules--choroidal segmentation; and 10 joules--globe rupture. CONCLUSIONS Impact thresholds correlating traumatic ocular pathology with impact energy followed a positive stepwise progression in severity with impact energies between 2 and 10 joules. Moderate angle recession commensurate with typical clinical traumatic glaucoma was not observed among control eyes, but occurred at relatively low impact energy of 3.5 joules among test eyes. Extensive disruption in and around the angle (iridodialysis/cyclodialysis) consistently occurred at energies >7 joules. Globe rupture required a minimum energy of 10 joules.