Postmortem changes in porcine eyes on computed tomography images

Porcine eyes were examined using postmortem computed tomography (PMCT) under controlled postmortem time and temperature conditions to assess the mechanisms and timing of changes in ocular structure. Eight porcine heads were halved, and PMCT scans were conducted from postmortem interval (PMI) days 0 to 13. CT images were obtained to evaluate the vitreous volumes, vitreous CT values, axial lengths of the eyes, lens dislocation, and intraocular gas. The vitreous volume decreased over time, with the highest median rate of 17.7 % at PMI 1, followed by 12.0 %, 11.7 %, and 11.3 % at PMIs 6, 7, and 8, respectively. There was a significant decrease in the axial eye length from PMIs 0 to 1, while the transverse diameter remained unchanged. Lens dislocation was observed in all cases at PMI 9. Receiver operating characteristic analysis using the PMI as the predictive value for the presence of lens dislocation revealed a cutoff value of PMI 6, with an area under the curve of 0.98. Intraocular gas was observed in four cases. In two cases with intraocular gas, intravascular gas appeared to be continuous with the intraocular gas via the ciliary body. Lens dislocation occurred 6 days postmortem in porcine eyes at moderate temperatures. Intraocular gas was also observed 6 days postmortem, which may have been caused by the influx of intravascular gas into the eye via the ciliary body. These structural changes in the porcine model, may help in estimating the time of death.