EXPLORE THE INDICATOR TO DETERMINE TIME SINCE DEATH USING PILOCARPINE EYE DROP

Abstract

Pupillary changes after death have long been a topic of interest for researchers and medico-legal specialists in determining the time of death. Pupillary changes after death can provide valuable information for determining the time of death. The eye drops method and the injection method are two commonly used techniques for monitoring pupillary changes. The eye drops method involves instilling a mydriatic or miotic agent into the eye and monitoring the subsequent changes in pupil size. Mydriatic agents such as atropine cause the pupils to dilate, while miotic agents such as pilocarpine cause the pupils to constrict. The time it takes for the pupil to reach its maximum size or minimum size can be used to estimate the time of death. However, these methods can vary in terms of onset of reaction times, which can affect the accuracy of the results. It is important to note that while the study of pupillary changes after death can provide valuable information, it is just one factor that is considered in determining the time of death. Other factors, such as the ambient temperature, the presence of rigor mortis, and the level of lividity, are also taken into account. It is also important to understand that determining the time of death with certainty can be challenging, and that different methods may yield different results. As such, it is always advisable to consider multiple sources of information and to use caution when interpreting the results of any single method. The objective of the present study is to determine the reaction time for effective miotic changes in pupil diameter, comparison between the changes in pupil diameter in left and right eye and make regression equation between pupillary changes and post mortem interval in different cause of death using pilocarpine eye drops. Total 583 deceased (1166 eyes) of known time of death were instilled with the 2% pilocarpine eye drop into conjunctival sac and changes were analysed using ImageJ freeware. In this study, author observed no statistically significant difference in reactivity of both the eyes in different time interval in different sex (p= 0.097). However, significant difference found in reactivity of both the eyes in different time interval in different age group (p= 0.0007) and cause of death (p = 0.015) at α < 0.05 using t-test and one way ANOVA test. Author concluded that left eye reacts faster xviii than right eye and a significant number of pupillary miotic changes are observed up to 30 minutes. The author observed no statistically significant difference between the reactivity of the left and right eye (p = 0.4446, at α < .05). A negative correlation between the changes of pupil diameter under the influence of the pilocarpine eye drop showed less change with increase PMI. Pearson correlation showed the negative correlation between the pupillary changes with PMI with p value 0.0001, 0.00017, 0.0341 and 0.0021 where α=0.05 for natural death, hanging, burn and poisoning respectively. Effective onset of reaction time for pupillary miotic alterations caused by pilocarpine eye drops should be around 30 minutes. While the largest number of cases across all age groups showed a reaction after 20 minutes, there were still instances where miotic changes occurred in 30 minutes. Additionally, there was a significant decrease in pupillary constriction after 30 minutes, and no reaction was observed in either eye after 40 minutes. Therefore, it would be reasonable to recommend waiting at least 30 minutes before assessing the effectiveness of pilocarpine eye drops in causing pupillary miotic alterations. Based on the information provided, it seems that both the right and left eyes react identically for all different causes of death, but the left eye tends to show better reactivity in a greater number of cases. This suggests that the left eye may be a more reliable indicator for determining time since death. Final results of the study suggest that a different regression equation should be applied when determining postmortem interval (PMI) based on the various causes of death. It is important to note that the limited number of samples for the various causes of death could be a factor contributing to the potential misinterpretation of the results.