Ocular and orbital trauma from water balloon slingshots: a clinical, epidemiological, experimental, and theoretical study.

PURPOSE

To report the clinical findings of 17 patients with ocular/orbital injuries produced by launched water balloons; to determine water balloon kinetic energies in experimental and theoretical studies.

METHODS

Six case histories are presented, 1 case was retrieved from the medical literature, and 10 cases were reported to the National Injury Information Clearinghouse of the United States Consumer Product Safety Commission. The energies were determined by field trials and calculations.

RESULTS

Injuries included orbital contusions and hematomas, facial hypesthesia, eyelid lacerations, subconjunctival hemorrhages, corneal edema and abrasion, hyphemas, traumatic iritis, iris sphincter ruptures, iris atrophy, angle recession, iridodialyses, traumatic cataract, vitreous hemorrhages, retinal hemorrhages, macular hole formation, optic atrophy, and bony orbital wall fractures. Epidemiological analysis revealed that children and young adults, more often males, were injured, most commonly in the warm weather months (May through September). In field trials, maximum water balloon velocities ranged from 38 to 41 m/sec (85 to 92 mph) with kinetic energies from 176 to 245 J; by calculation, maximum velocities ranged from 42 to 54 m/sec (95 to 121 mph) with kinetic energies from 141 to 232 J. In a field demonstration a 300-g water balloon launched horizontally from a distance of 20 ft exploded a 12-kg watermelon. Classic physics calculations are presented to explain the complex bio-mechanical interactions between the water balloon and the eye.

CONCLUSION

Kinetic energies of launched water balloons are comparable to or greater than kinetic energies experienced with a variety of common objects, including file bullets, which are well known to cause serious ocular and orbital injuries. In addition, these energies are far in excess of those required to perforate a cornea (0.7 to 1.7 J), rupture a globe (1 to 5.3 J), or fracture the bony orbit (1.8 to 14.7 j). Thus, this study demonstrates the serious and potentially vision- and life-threatening injuries inflicted by these "toys."