Subjective versus digital image analysis of the corneal opacity as a tool for estimation of time since death with studying the effect of eye closure and ambient temperature

Abstract
Estimation of time pass since death is a great forensic confrontation. Corneal opacity is an endorsed forensic tool for estimation of time pass since death. Previous researches depend on subjective way while others used digital image analysis system. In this study we compare subjective and digital image analysis methods, in addition to studying effect of eye closure and temperature on development of corneal opacity. Closed and opened rabbit eyes corneas were photographed at different postmortem intervals. A scoring system was used to assess the cornea opacity. Image analysis was done by MATLAB software. Simple regression analysis revealed better prediction of the postmortem intervals using image analysis parameters than when subjective assessment was employed. On using multiple regression analysis, there is improvement of SEE from 2.5-3.6 hr. to 1.1-1.3 when using equation of 3 elements of colors red, green and blue. Corneal opacity slightly increased in closed eye than in opened one. In summer corneal opacity occur faster than in winter.
Key words: time pass since death, corneal opacity, digital imaging, eye closure, temperature