Pupillary Reaction to Various Drugs and Substances

PUPIL REACTION TO SUBSTANCE/DRUGS

Pupil of human eye constrict and dilate depending upon the need of the eye to focus on near object/far object, dim light/bright light and whether it is under stress/not. This response is solely dependent upon the muscles inside the eyes in the iris. The pupillae constrictor muscle respond to cholinergic agents and cause pupillary constriction while the dilator pupillae muscle is acted upon by sympathetic system and causes pupillary dilation.

Beside these natural response, the substances we come in contact with can also alter the pupillary size. Drugs such as Adrenaline, antidepresssants, antihistaminics, can cause pupillary dilatation. Pethidine being an exception is the only opoid to cause pupillary dilation. Herbal products such as belladona, strychinine, calotropis and Chemicals such as alcohol, formic acid, cyanide Carbon monoxide also have dilatatory effect based upon the dosing.

Phenols, Organophosphate, carbamates, Carbolic acid, cause pupillary cosntriction. Drugs such as Opoids, barbiturates, Benzodiaepines, methyl dopa and plant product such as Nicotine, caffiene and opium causes the dilatation of pupil. 

Know how to assess the pupillary reaction or light reflex.

DILATORS		CONSTRICTORS
A6 C5 (Big1 Co Ca Cola Can)		O2 B2 C5 ( Car Car Caf )
Formic Acid			Phenol (Carbolic Acid)
Pethidine2 (only exception in Opoid)		O	All Opoids2  (Except severe Acidosis/hypoxia/ respiratory depression)
Adrenaline*/ Ephidrine/Sympathetomimetics	A		Parasympathetomimetics*
Atropine*/ Belladona/ Dhatura	A	O	Organophosphate*
Amphetamine	A	B	Barbiturates
Alcohol3	A	B	Benzodiazepines
Antidepressants	A
Antihistaminics	A
Cocaine Crack	Co	Car	Carbamate
Carbon Monoxide/ CO	Ca/CO	Car	Carbolic Acid
Calotropis	Cola	Caf	Caffeine
Cannabis	Can		Coma of Alcohol3
Cyanide			Clonidine
Hypothermia*			Heat Stroke*
Strychnine			Nicotine4
			Methyl Dopa

HIPPUS: Alternating dilatation and constriction is done by ACONITE

Note: All A’s constrict the pupil. All B’s and O’s dilate the pupil.

¹ Big is not a part of drug rather means dilatation.

² Only opoid to cause pupillary dilatation is Pethidine.

³ Toxic Effect of alcohol causes pupillary constriction as patient develops coma.

⁴ Delayed effect of Nicotine is dilatation of pupil.

* The drugs/substances in row with different color across the table are physiological Counterparts

  

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