Postmortem Ocular Findings in the Optical Coherence Tomography Era: A Proof of Concept Study Based on Six Forensic Cases

Ocular Surface Fluid: More than a Matrix

Although the eye can be subjected to therapeutic manipulation, some of its structures are highly inaccessible. Thus, conventional therapeutic administration pathways, such as topical or systemic routes, usually show significant limitations in the form of low ocular penetration or the appearance of side effects linked to physiology, among others. The critical feature of many xenobiotics is the drug gradient from the concentrated tear reservoir to the relatively barren corneal and conjunctival epithelia, which forces a passive route of absorption. The same is true in the opposite direction, towards the ocular surface (OS). With the premise that tears can be regarded as equivalent to or a substitute for plasma, researchers may determine drug concentrations in the OS fluid. Within this framework, a survey of scholarly sources on the topic was conducted. It provided an overview of current knowledge, allowing the identification of relevant theories, methods, and gaps in the existing research that can be employed in subsequent research. OS fluid (tears particularly) has enormous potential as a source of biological material for external drug screening and as a biomarker of various systemic diseases. Given the numerous alternate matrices, knowledge of their properties is very important in selecting the most appropriate specimens in toxicological analyses.

Structural changes in the crystalline lens as a function of the postmortem interval assessed with two-photon imaging microscopy

The properties and structure of the crystalline lens change as time after death passes. Some experiments have suggested that these might be used to estimate the postmortem interval (PMI). In this study, the organization and texture of the rabbit lens were objectively evaluated as a function of the PMI using two-photon excitation fluorescence (TPEF) imaging microscopy. Between 24 h and 72 h, the lens presented a highly organized structure, although the fiber delineation was progressively vanishing. At 96 h, this turned into a homogeneous pattern where fibers were hardly observed. This behaviour was similar for parameters providing information on tissue texture. On the other hand, the fiber density of the lens is linearly reduced with the PMI. On average, density at 24 h was approximately two-fold when compared to 96 h after death. The present results show that TPEF microscopy combined with different quantitative tools can be used to objectively monitor temporal changes in the lens fiber organization after death. This might help to estimate the PMI, which is one of the most complex problems in forensic science.

The eye in forensic practice: In the dead

Post-mortem examination of the eye provides valuable forensic information yet is often overlooked. This brief review focuses on determining the cause/manner of death and post-mortem interval. External eye findings like corneal haziness and tache noire, combined with post-mortem changes in the iris, lens, retina and vitreous humour, can help estimate time since death. Ocular biometrics (iris/retinal scans) may facilitate identification. Age-related ocular changes can provide insights. The eye offers clues into personality (corneal tattooing, trichotillomania) and cause of death (petechiae in strangulation, retinal haemorrhages in abusive head trauma). Ocular trauma and underlying eye disease may be evident. Toxicology of vitreous humour can detect drugs/poisons. As a window into systemic disease and age-related changes, the eye aids pathology interpretations and, accordingly, post-mortem examinations have value. Ocular findings should not be overlooked in forensic examinations as they provide distinct information in determining cause/manner of death and post-mortem interval.

Ophthalmic imaging in abusive head trauma

BACKGROUND

Ophthalmic imaging plays an increasingly important role the evaluation of abusive head trauma, however these imaging modalities may be unfamiliar to non-ophthalmologists.

OBJECTIVE

To provide pediatricians and child abuse pediatric professionals with background on ophthalmic imaging techniques in the context of suspected abuse, as well as information on commercial options and costs for those interested in augmenting their ophthalmic imaging capabilities.

METHODS

We performed a review of the ophthalmic imaging literature for fundus photography, ocular coherence tomography, fluorescein angiography, ocular ultrasound, computed tomography, magnetic resonance imaging and postmortem imaging. We also contacted individual vendors for equipment pricing information.

RESULTS

For each ophthalmic imaging modality, we demonstrate its role in the evaluation of abusive head trauma including indications, potential findings, sensitivity and specificity of findings for abuse, and commercial options.

CONCLUSIONS

Ophthalmic imaging is an important supportive component of the evaluation for abusive head trauma. When used in conjunction with clinical examination, ophthalmic imaging can improve diagnostic accuracy, support documentation, and possibly improve communication in medicolegal contexts.

Keep an eye on the crime – a new look at the forensic use of post-mortem eye examination to estimate time of death

Determining the time of death plays a crucial role in a forensic post-mortem examination. Many methods for the time of death (TOD) determination have been developed. However, most are not applicable during the first hours after death and produce large post-mortem interval (PMI) ranges. Eye examination makes it possible to precisely determine the time of death during the initial period after death with half-hour accuracy.. In recent years methods for estimating the time of death by measuring the changes in the eye have made great strides. Those methods use the changes in the reaction to drugs and macroscopically visible morphological changes. Experimental studies also produced equations that can estimate the post-mortem interval using biochemical, electrochemical and thermal changes within the eye.

The Influence of Eyelid Position and Environmental Conditions on the Corneal Changes in Early Postmortem Interval: A Prospective, Multicentric OCT Study

In the current study, using portable optical coherence tomography, we evaluated 46 corneas of 23 individuals in a multicenter setting during the first 17 h after death. Twenty-three eyes were kept open, and twenty three were kept closed. Furthermore, the experiment was carried out for 12 samples in summer and 11 in winter. Our data show that postmortem corneal alterations largely depend on the phenomena of dehydration (in particular in open eyes) and swelling of the stroma in closed eyes, probably due in the first phase to hypoxia/anoxia and subsequently to the passage by osmosis of the aqueous humor from the anterior chamber to the corneal tissue. Our findings could have significant repercussions in forensic pathology for estimating the postmortem interval and transplantation to optimize the conservation of the tissue before the explant.

The Eye in Forensic Medicine: A Narrative Review

ABSTRACT

The eye, with its distinctive anatomy, not only reflects a wide variety of diseases in life but also undergoes a myriad of post-mortem changes. Consequently, the eye has long been an area of interest in forensic science, primarily for the estimation of post-mortem interval and therefore the time of death and also for assistance in ascertaining the cause of death. There has been significant progress in the knowledge of ophthalmic forensic science using new technologies which have allowed further possibilities to arise where understanding of this field can assist the forensic pathologist. This review aims to highlight the current knowledge which exists in this field and also to identify important avenues for further investigation. Post-mortem changes of the eye along with its current applications and challenges will be discussed. These include the important areas of post-mortem iris biometrics, pupil size correlation with post-mortem interval, use of point-of-care technology on vitreous humor, and the use of ophthalmic imaging in pediatric abusive head trauma.