Abstract
Purpose :
Identifying pediatric abuse is crucial but challenging due to inconsistencies in case classification, and notable variations in the reported injuries. While retinal hemorrhage has been an important biomarker for shaken baby syndrome (SBS), recent studies propose that blunt traumas can induce comparable ocular and neurological injuries. Thus, our goal was to identify biomechanical characteristics that independently distinguish blunt traumas from SBS cases, and subsequently establish a link with frequently reported ocular injuries.
Methods :
Finite element simulations were conducted on pediatric eye models to assess their mechanical response to blunt traumas and SBS. We chose to evaluate the impact of a soccer ball and a badminton birdie, traveling at speeds of 50 and 80 mph, respectively, for the analysis of blunt traumas. The SBS scenario was reproduced using trajectory paths from biomimetic tests found in the literature. Retinal stress and strain energy were computed due to their capability to comprehensively describe the incidence of eye injury.
Results :
The birdie’s blunt impact showed a greater degree of damage, evidenced by a retinal stress of 45.83 kPa and a strain energy of 164.43 mJ. In comparison, the soccer and SBS simulations exhibited lower retinal stresses of 11.18 kPa and 6.50 kPa, along with strain energies of 63.59 mJ and 0.70 mJ, respectively (Fig. 1). Despite the soccer ball’s higher kinetic energy, the birdie, due to its size fitting within the orbit, transferred most of its energy directly to the eye. In contrast, the soccer ball stored and dissipated a generous portion of energy.
Due to the dynamic nature of impacts, stress and energy metrics showed peaks upon eye contact, followed by an exponential decay. However, SBS results indicated a constant amplitude of these metrics over time.
Conclusions :
Blunt ocular traumas are susceptible to severe injuries beyond retinal hemorrhage, unlike SBS, as the involved dynamic energy is not comparable to the shaking motion of an infant’s head. Even in the inelastic collision of a soccer ball, where a significant amount of energy was dissipated, the resulting stress and strain energy within the eye exceeded those observed in the SBS case. This fact aligns with the high incidence of acute lesions in sport ocular traumas such as retinal detachment, lens dislocation, optic neuropathy, and traumatic glaucoma, which are rarely found in SBS.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.