Risks and regulation of rubber scattershot in Switzerland: a narrative review

Multiple kinetic impact projectiles (KIPs) are responsible for most eye injuries by crowd-control weapons. This review aims to outline an underreported, ongoing series of eye injuries by rubber scattershot in Switzerland, and to relate current knowledge about thresholds for lasting visual loss to the energy limits set on KIPs in crowd control, by way of a retrospective compilation of cases from publicly available records and a review of the pertinent literature. Scattershot can cause irreversible visual loss. Since 1980, there have been 36 known cases of eye injuries by rubber pellets in Switzerland. In 2023, the incidence was higher here than at the peak of protests in France. KIPs were originally cleared for use in crowd control at kinetic and area-normalised energies assumed to lie below the threshold for ocular penetration. However, closed globe injuries suffice to cause permanent visual loss. Lower energy thresholds for lasting damage have been confirmed by the newer literature on paintballs, airbags, air guns and toys. These values may differ in vivo versus in vitro, and in humans versus in animals. There is no clear consensus on how best to predict loss of vision. Underreporting the risks of crowd-control weapons may contribute to their prolonged and increasingly liberal use. Regulations should consider what is known on energy thresholds for permanent visual loss. It is critical for ophthalmologists to be involved in the evaluation and monitoring of eye injuries caused by projectiles, including KIPs and toys. An interdisciplinary approach could help to elucidate damage thresholds.