Postmortem Sympathomimetic Iris Excitability.

BACKGROUND

A reliable estimation of time since death can be important for the law enforcement authorities. The compound method encompassing supravital reactions such as the chemical excitability of the iris can be used to further narrow intervals estimated by temperature-based methods. Mostly postmortem iris excitability by parasympatholytic or parasympathomimetic substances was assessed. Little is known regarding sympathomimetic agents. The present study aims to describe the postmortem iris excitability using the sympathomimetic drug phenylephrine.

METHODS

30 eyes from 16 cadavers (median age = 80.0; 9 males, 7 females) were examined. Cadavers were included after body donors gave written informed consent during lifetime. Cadavers were excluded if there was a known eye disease, or the postmortem interval exceeded 26hours. The median postmortem interval until drug application was 15.5hours. A pupillometer with a minimum measurement range of 0.5mm was used to determine horizontal pupil diameter before and 20minutes after drug application. Increase in pupil diameter was labeled as positive reaction, unchanged pupil diameter was labeled as negative reaction, and decrease in pupil diameter was labeled as paradox reaction.

RESULTS

Initial pupil size was in median 3.5mm (interquartile range [IQR]: 3.0 to 4.5mm) and progressed to 4.0mm (range: 3.5 to 5.0mm) 20minutes after drug instillation. The achieved pupil diameter difference comprised 0.5mm in median (IQR: 0.0 to 1.0mm). A positive reaction was observed in 21 cases. No reaction was observed in 5 cases. Paradox reaction was observed in 4 cases. Overall, there was a statistically significant difference in diameter between the initial and the reactive pupil (P = 0.0002; Wilcoxon-signed-rank test).

CONCLUSION

Although relatively rarely used, sympathomimetic drugs seem to be eligible for chemical postmortem iris excitability. Currently, assessment of postmortem iris excitability usually only involves parasympatholytic and parasympathomimetic agents. The findings of the present study give a hint that the application of a third agent with a sympathomimetic mechanism of action could provide additional information. Further studies assessing such a triple approach in the compound method in comparison with the current gold standard for estimation of time since death are mandatory to ensure reliable results.

Informations de copyright

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Déclaration de conflit d'intérêts

Declaration of Competing Interest The authors declare that they have no competing interests. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.