Determination of postmortem interval by sampling vitreous humour.

Estimation of postmortem interval (PMI) by analyses of vitreous humor has certain advantages over analyses of blood and cerebrospinal fluid (CSF). Certain substances, including potassium and hypoxanthine (Hx), have been shown to exhibit postmortem increase in concentration in vitreous humor in a linear fashion. In the present study, potassium and Hx concentrations were measured in 100 subjects with known PMIs. Three previously published equations were used to estimate the PMI using these measurements, and the accuracy of the equations was assessed. Simple linear regression analyses were performed on the data collected, and new equations for estimation of PMI were constructed. Estimates made using these equations were of comparable or better accuracy than those made using the published equations. It was observed that using both potassium and Hx measurements to estimate the PMI were associated with increased accuracy in all circumstances.