The use of pilocarpine eye drops for estimating the time since death

• This study demonstrated that pilocarpine can constrict pupils for a period of time after death.
• The longest duration that the pupil showed reaction was found to be about 15 h.
• The change in pupils after application of pilocarpine decreased with an increase in the postmortem interval (PMI).
• The change in pupil size and PMI were found to be correlated in a statistically significant manner.
• Regression analysis was performed to determine the correlation between change in the pupil and PMI.

ObjectiveThe objective of this study was to estimate the time since death using pilocarpine eye drops.MethodsIn this study, 100 postmortem cases with known time of death were included. In each case, the left pupil was measured in millimeter units using a vernier caliper, and pilocarpine eye drops were applied. The pupil was measured again 10 min later, and statistical analysis was used to analyze the correlation between the time since death and the change in the pupil.ResultsThe longest duration since death that the pupils showed reaction to pilocarpine was 15 h. The correlation between the change in the pupil and the postmortem interval was found (Spearman's rho, r = −0.304, p = 0.002), and the change in the pupil may be used to predict the postmortem interval by the following regression equation: postmortem interval (PMI) = 8.310−3.702 (Diff) ± 0.735 (PMI was postmortem interval in hours and Diff was the difference in the size of the pupil after administering pilocarpine in millimeter units).ConclusionThe present study showed that pilocarpine eye drops can be used to estimate the time since death.