Mini Review - Journal of Clinical Ophthalmology (2022) Volume 6, Issue 4
Optometry in crime scene investigation.
- Corresponding Author:
- Dr. Raj Kumar
Department of Optometry
Received: 31-May-2022, Manuscript No. AACOVS-22-63107; Editor assigned: 03-Jun-2022, PreQC No. AACOVS-22-63107 (PQ); Reviewed: 17-Jun-2022, QC No. AACOVS-22-63107; Revised: 30-Jun-2022, Manuscript No. AACOVS-22-63107 (R); Published: 07-Jul-2022, DOI: 10.35841/aacovs.6.4.552-554.
Citation: Kumar R, Kaur A. Optometry in crime scene investigation. J Clin Ophthalmol. 2022;6(4):552-554.
Biological fluids such as blood, saliva, urine, semen, vaginal secretions etc. carry a great evidentiary value when found at the crime scene. But due to lack of awareness in case of tears. The presence of tears at the crime scene reflects that the person was emotionally disturbed such as in the case of kidnapping, physical torture, suicide/murder, etc. Therefore the ophthalmic evidence such as spectacles, contact lenses, etc. strengthens the evidentiary value. Forensic Optometry is yet to get streamlined along with the routinely followed investigative techniques and scientifically explored although no standard protocols exist to analyze eyewear.
Tears, Biological fluids, Saliva, Investigation, Crime scene, Physical torture.
Composition of tears
The lachrymal glands present in the eyes secrete a transparent liquid called tear. Tears can be differentiated into 3 layers i.e. lipid, aqueous, mucous . The composition of tears includes water, antibodies, salts, antibacterial enzymes. Adrenocorticotropic hormone and leucine enkephalin are the stress hormones that are present in higher concentration in emotional tears (Tables 1 and 2) (Figure 1).
|1||Lipid||Contains Oil||Secreted by the tarsal glands||The lipid layer provides a hydrophobic barrier that coats the aqueous layer|
|2||Aqueous||Contains 60 metabolites and Electrolytes||Secreted by lacrimal glands||It controls the osmotic regulation and also the infectious agents|
|3||Mucous||Contains Mucin (have ability to form gels)||Secreted by conjunctival goblet cells||It provides a hydrophilic layer and coats the cornea|
Table 1. Composition of tears.
|1||Basal||For the lubrication of the cornea small quantities of tears are released continuously. They fight against infectious agents such as viruses, bacteria, etc., and are also considered a part of our immune system. These are also called basic functional tears because they ensure comfort and good visual acuity|
|2||Reflex||They are also known as Irritation tears because they are the result of the irritation caused in the eyes due to the foreign particles. They can also occur due to bright light. They are produced in higher quantities than the basal tears but the goals are the same|
|3||Emotional||Also called Psychic tears, crying, etc. These result from strong emotions such as sorrow, anger, happiness, etc|
Table 2. Types of tears and their description.
Prospects of tear examination
Biological body fluids play an important role in personal identification such as blood, saliva, semen, tear, etc [2,3]. Tears are exposed to both the internal and external environment; possess the significant value in determining the molecular information to diagnose ocular diseases.
Sample collection and storage of tear
During crime scene investigation, tear samples can be present on the tissue papers, bed sheet, and handkerchief. The body fluids possess the property of fluorescence when they are examined under the light of different wavelengths [4,5]. A tear sample is collected from the subject’s conjunctival sac of the eye in a small glass capillary tube.
Direct sampling method
In 2013, researchers worked on the tear cytokine response to multipurpose solution for contact lenses. Before the lens removal, from the inferior tear meniscus non stimulated tears were collected from both eyes with the help of 10 microlitre flame polished glass micropipette.
Then, immediately 5.5 microliters of the tear is transferred to a sterile, 0.2 ml tube which contains 49.5 microliter storage mixture at -80°C.
Indirect sampling method
Pre-Corneal Tear Film (PCTF) is collected with the help of Schirmer’s test strip, other absorbing materials such as cellulose sponge, filter paper, etc. (Figure 2).
ELISA: Enzyme-Linked immune-sorbent Assay technique is used to analyze inflammatory markers in PCTF.
A weak cell sponge is used to collect 10 microliters of tears [6,7]. The concentrations of interleukin (IL) 1_, IL-6, and pro-MMP-9 were measured by Enzyme-Linked Immune-Sorbent Assay (ELISA), and the MMP-9 activity was evaluated with gelatin zymography.
Luminex technology: To quantify the cytokine profile ophthalmic sponges and extraction buffer are compared using Luminex technology.
Merocel sponge is used to collect the cytokine profiles of tears. Past few year study by authors on the collection method of tear (Studies were performed on humans).
Significance of tear in personal identification
The process of investigation involves the identification of the suspect/criminal. Therefore a subject to objective approach is followed by the forensic laboratories. DNA Technology is used for the identification of known/unknown individuals in the cases such as genealogy studies, maternity/paternity testing . The use of tear along with the eyewear examination can strengthen the ease of identification. They are secreted in small quantities and are found in a dried state which can be diagnosed using presumptive test and can be confirmed using the confirmatory test [9,10].
The ophthalmic aids such as spectacles (color, frame shape, dimensions, prescription etc.) contact lenses, etc. have proved to hold a good evidentiary value in the crime scene investigation as they can give the idea about the gender, age, type of refractive error in the eye.
In many cases, it has been reported that the fragments of the lens give a positive match with the prescription data. The refractive error of an unknown lens can be measured by using the different type of focimeter or vertometer. So tear, spectacles, contact lenses Eyewear prescription databases act as excellent forensic evidences in crime investigation and personal identification. The ocular surface changes also help to determine the time since death.
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