Development and Validation of a Synthetic Eye and Orbit for Estimating the Potential for Globe Rupture Due to Specific Impact Conditions

The Facial and Ocular CountermeasUre Safety (FOCUS) headform is intended to aid safety equipment design in order to reduce the risk of eye and facial injuries. The purpose of this paper is to present a three part study that details the development and validation of the FOCUS synthetic eye and orbit and the corresponding eye injury criteria. The synthetic eye and orbit were designed to simulate the force-deflection response to in-situ dynamic impacts. In part I, the force-deflection response of the eye was determined based on dynamic blunt impact tests with human eyes. These data were used to validate the appropriate material for a biofidelic synthetic eye. In part II, force-deflection corridors developed from ten dynamic in-situ eye impacts were used to validate the design and material selections for the synthetic orbit assembly. In part III, 82 experimental tests on the FOCUS headform were conducted using steel BB projectiles to develop a conservative injury risk criteria for the FOCUS headform based on the response of the eye load cell. Injury criterion for globe rupture is strongly correlated to the data from the FOCUS eye load cell (R² = 0.995). Based on the response of the FOCUS eye load cell, a 50% risk of globe rupture from a 4.5 mm BB impact is shown to be 107 N. With a biofidelic synthetic eye and this projectile-specific injury criteria, the FOCUS headform can be used to conservatively evaluate the risk of globe rupture from ≥4.5 mm diameter projectile impacts to the eye.