Vitreous Humour
Definition
The gel-filled interior of the eye, anatomically isolated from hepatic and gastric post-mortem redistribution sources. In forensic toxicology of hooch deaths, vitreous methanol concentrations are more reliable ante-mortem concentration surrogates than central blood, particularly when post-mortem intervals are prolonged.
- What it is
- A transparent gel that fills the eyeball between the lens and retina
- Collection volume
- 1 to 2 millilitres per eye via fine needle
- Key forensic advantage
- Low bacterial load and resistance to post-mortem redistribution make it ideal for toxicology
Common questions
Why is vitreous humour used for testing ethanol and drug levels in poisoning cases?+
The vitreous humour is a relatively isolated, low-bacterial fluid inside the eye that resists post-mortem redistribution. Because it's separated from the gut and major blood vessels, it preserves drug and alcohol levels better than other fluids like central blood, especially when the body has been dead for a long time.
How is vitreous humour collected during autopsy?+
A fine needle is inserted through the lateral canthus (corner) of each eye to withdraw 1 to 2 millilitres of the gel. This simple procedure gives toxicologists a sample they can analyse for ethanol, glucose, electrolytes, and several drug classes.
What makes vitreous humour reliable in methanol poisoning deaths?+
Methanol concentrations in vitreous humour reflect the victim's ante-mortem exposure more accurately than central blood, because the eye is anatomically isolated from the liver and stomach where post-mortem chemical changes occur. This makes it especially useful when the body has been dead for hours or days.
Related terms
- Post-Mortem Redistribution (PMR)
- The phenomenon where drug and poison concentrations shift between body compartments after death, generally moving out of solid organs back into the...
- Viscera
- The standard set of organs and fluids collected at a suspected poisoning autopsy in India: stomach with contents, a length of upper...
- Alcohol Dehydrogenase (ADH)
- The hepatic enzyme (isoforms ADH1A, ADH1B, ADH1C) that catalyses the first oxidation step of both ethanol (to acetaldehyde) and methanol (to formaldehyde)...
- Anion-Gap Metabolic Acidosis
- The metabolic acid-base disorder produced by accumulating formate in methanol poisoning. The anion gap (Na+ - [Cl- + HCO3-], normal 8-12 mEq/L)...
- BNSS Forwarding Form
- The viscera-forwarding requisition that accompanies sealed bottles from the autopsy mortuary to the SFSL or CFSL. Successor to the CrPC-era Form 65...
- Chain of Custody
- The documented chronological record of who collected, handled, transferred, and examined a piece of evidence. For digital evidence, chain of custody includes...
- Congener Fingerprinting
- The use of the full volatile congener profile (fusel alcohols, acetaldehyde, ethyl acetate, pyridine, MIBK) in illicit liquor samples to establish batch...
- Decontamination
- The wash protocol applied to hair or nails before extraction, intended to remove sweat, sebum and external contamination so that the assay...
- Femoral Blood
- Peripheral venous blood drawn from the femoral vein after clamping it off proximally. Considered the gold-standard antemortem-equivalent matrix because it is anatomically...
- Fomepizole (4-Methylpyrazole)
- A specific competitive inhibitor of alcohol dehydrogenase (Ki approximately 0.1 µM), used as the preferred antidote for methanol poisoning in high-resource settings....
- Formate (Formic Acid)
- The terminal toxic metabolite of methanol oxidation (HCOO-, pKa 3.7). Formate inhibits cytochrome c oxidase (mitochondrial complex IV), causing optic nerve and...
- FSSAI Methanol Limit
- Under India's Food Safety and Standards (Alcoholic Beverages) Regulations 2018, the maximum methanol content permitted in legally produced and sold spirits is...
Explained in these topics
- Biological, Non-Biological and Viscera Matrices in ToxicologyThe gel inside the eyeball. Relatively isolated from gut and great vessels, slow to putrefy, and the preferred matrix for post-mortem ethanol quantitation.
- Methanol, Hooch Tragedies and Illicit Liquor ChemistryThe gel-filled interior of the eye, anatomically isolated from hepatic and gastric post-mortem redistribution sources. In forensic toxicology of hooch deaths,...
- Post-Mortem Examination and Viscera Collection in PoisoningThe transparent gel filling the eyeball between the lens and the retina. A relatively isolated, low-bacterial-load fluid that resists post-mortem redistributio...