Postmortem changes in porcine eyes on computed tomography images

Area of Science:

• Forensic Pathology
• Ophthalmology
• Radiology

Background:

• Accurate estimation of postmortem interval (PMI) is crucial in forensic investigations.
• Understanding postmortem changes in ocular structures can provide reliable indicators for PMI estimation.
• Porcine eyes offer a relevant model for studying human postmortem ocular changes due to anatomical similarities.

Purpose of the Study:

• To investigate the temporal changes in porcine ocular structures using postmortem computed tomography (PMCT).
• To assess the utility of specific ocular changes, such as vitreous volume, axial length, and lens dislocation, in determining the postmortem interval.
• To explore the occurrence and potential mechanisms of intraocular gas formation in postmortem porcine eyes.

Main Methods:

• Eight porcine heads were subjected to PMCT scans at controlled postmortem intervals (PMI) from day 0 to 13.
• CT imaging was used to quantify vitreous volume, vitreous CT values, and axial eye length.
• The presence of lens dislocation and intraocular gas was systematically evaluated.
• Receiver operating characteristic (ROC) analysis was performed to determine the predictive value of lens dislocation for PMI.

Main Results:

• Vitreous volume showed a progressive decrease, with the highest rate (17.7%) observed at PMI 1.
• A significant reduction in axial eye length occurred between PMI 0 and 1, while transverse diameter remained stable.
• Lens dislocation was consistently observed by PMI 9, with ROC analysis indicating a cutoff value of PMI 6 for its prediction (Area Under Curve = 0.98).
• Intraocular gas was detected in four cases, with evidence suggesting continuity with intravascular gas via the ciliary body.

Conclusions:

• Lens dislocation at 6 days postmortem in porcine eyes is a reliable indicator of PMI at moderate temperatures.
• The development of intraocular gas, potentially linked to intravascular gas migration, also occurs around 6 days postmortem.
• These PMCT-identified structural changes in porcine eyes provide valuable insights for postmortem interval estimation in forensic science.