An experimental study on the association between postmortem corneal fold change and postmortem interval

Abstract:

Objective：To investigate the temporal variation of corneal folds after death using the digital image analysis technique，and to screen out appropriate quantitative indicators. Methods：Rabbits were randomly divided into open-eye group and closed-eye group after hanging，with 20 rabbits in each group，and then they were placed in a dark room at a temperature of 20 ℃. A digital camera was used to capture rabbit corneal images at a one-hour interval within 72 hours after death. MATLAB software was used to obtain the im－ages of the pupil region of the cornea，and the four parameters of image texture features（CON，COR，ASM，and HOM） which reflected the postmortem change of corneal folds were extracted dynamically. The two groups were compared in terms of the variation trend of each parameter with postmortem interval（PMI），and the correlation between each parameter（y） and postmortem interval（x） was ana－lyzed. Results：CON increased with PMI and COR decreased with PMI in both groups，but compared with the closed-eye group，the open-eye group had significantly faster and greater changes. CON and COR were significantly correlated with PMI（P<0.05），and the regression equations were y=0.002 4x2-0.026 8x+0.467 3（CON，R2=0.978 in the open-eye group），y=0.000 4x2-0.010 6x+0.304 4（CON，R2=0.904 in the closed-eye group），y=-0.000 4x2+0.014 2x+3.893 8（COR，R2=0.938 in the open-eye group），and y=-3E-05x2+0.001 2x+3.980 8（COR，R2=0.852 in the closed-eye group）. ASM and HOM had no significant correlation with PMI（P>0.05）. Conclusion：The temporal variation of corneal folds is observed after death，and the texture features of CON and COR are well corre－lated with PMI.