Ocular and associated brain injuries caused by less-lethal kinetic impact projectiles: A systematic review

Kinetic impact projectiles (KIPs), used by law enforcement and in crowd control, are "less-lethal" weapons designed to reduce injury risk. However, they can cause severe craniofacial trauma, particularly to the orbit, a vulnerable structure that may transmit impact forces to the brain. This systematic review evaluates ocular and orbital injuries caused by KIPs, focusing on associated brain injuries, sequelae, and forensic implications. A systematic review was conducted following PRISMA 2020 guidelines and registered in PROSPERO (CRD420261294742). PubMed, Scopus, and Embase were searched up to February 13, 2026, without date restrictions. Studies reporting human ocular or orbital injuries caused by KIPs with associated intracranial injuries were included. Two reviewers independently selected studies, extracted data, and assessed risk of bias using Joanna Briggs Institute tools. A narrative synthesis was performed due to study heterogeneity. Nine of 345 studies were included, comprising case reports, case series, and one retrospective study. Injuries mainly occurred in crowd-control settings and involved rubber bullets, bean bag rounds, foam projectiles, and plastic bullets. Ocular injuries ranged from contusions to globe rupture and enucleation, frequently causing permanent vision loss. Orbital fractures were common and often associated with facial injuries. Intracranial injuries, including subarachnoid hemorrhage, subdural hematoma, pneumocephalus, and brain contusions, were reported, although the relationship between orbital and brain injuries was inconsistently described. KIP-related injuries range from isolated ocular trauma to severe cranio-orbital injury. The orbit may transmit impact forces to the brain, but mechanisms remain unclear. Standardized reporting and biomechanical research are needed to improve forensic interpretation.