Purpose: The authors report the findings of 17 patients with ophthalmic injuries produced by launched water balloons; they determine water balloon kinetic energies in experimental and theoretical studies.
Methods: Six case summaries are presented; one case report was retrieved from the literature; ten injuries were reported to the Consumer Product Safety Commission. Energies were determined by field trials and calculations.
Results: Injuries included periorbital edema and ecchymoses, orbital contusions and hematomas, maxillary sinus hematomas, facial hypesthesia, eyelid lacerations, subconjunctival hemorrhages, corneal edema and abrasions, hyphemas, traumatic iritis, iris sphincter ruptures, iris atrophy, angle recession, iridodialysis, traumatic cataract, vitreous hemorrhages, retinal hemorrhages, macular hole formation, optic atrophy, and bony orbital wall fractures. Epidemiologic analysis revealed that children and young adults, more often males, were injured, most commonly in the warm weather months. In field trials, maximum water balloon velocities ranged from 38 to 41 m/sec (85-92 mph) with kinetic energies from 176 to 245 joules; by calculation, maximum velocities ranged from 42 to 54 m/sec (95-121 mph) with kinetic energies from 141 to 232 joules. In a field demonstration, a slingshot-launched water balloon exploded a watermelon.
Conclusion: Energies are comparable to or greater than those experienced with a variety of common objects, including some rifle bullets that are known to cause serious ophthalmic injuries. These energies are far in excess of those required to perforate a cornea, rupture a globe, or fracture the bony orbit. This study demonstrates the serious and potentially vision- and life-threatening injuries inflicted by these "toys."