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A human adult exhibiting voluntary control over his iris muscles, where he can cause his pupil to dilate and constrict on command. A dilation response , is the widening of the pupil and may be caused by adrenaline; anticholinergic agents; stimulant drugs such as MDMA, cocaine, and amphetamines; and some hallucinogenics (e.g. LSD). [2]
Additionally, nicotine can cause constriction of the blood vessels, reducing blood flow to the eyes and making them more vulnerable to damage and disease. [30] It is recommended that smokers exhibiting signs and symptoms of retinopathy engage in smoking cessation to improve their quality of life.
Nerves involved in the resizing of the pupil connect to the pretectal nucleus of the high midbrain, bypassing the lateral geniculate nucleus and the primary visual cortex. From the pretectal nucleus neurons send axons to neurons of the Edinger-Westphal nucleus whose visceromotor axons run along both the left and right oculomotor nerves .
Certain drugs cause constriction of the pupils, such as opioids. [7] Other drugs, such as atropine, LSD, MDMA, mescaline, psilocybin mushrooms, cocaine and amphetamines may cause pupil dilation. [8] [9] The sphincter muscle has a parasympathetic innervation, and the dilator has a sympathetic innervation.
The short-term physiological effects of cocaine include [11] constricted blood vessels, dilated pupils, and increased temperature, heart rate, and blood pressure. Some users of cocaine report feelings of restlessness, irritability, and anxiety. In rare instances, sudden death can occur on the first use of cocaine or unexpectedly thereafter.
Mydriasis is frequently induced by drugs for certain ophthalmic examinations and procedures, particularly those requiring visual access to the retina. Fixed, unilateral mydriasis could be a symptom of raised intracranial pressure. The opposite, constriction of the pupil, is referred to as miosis. Both mydriasis and miosis can be physiological.
Substances that may cause this toxidrome include cocaine, amphetamine and compounds based upon amphetamine's structure such as ephedrine , methamphetamine, phenylpropanolamine and pseudoephedrine. The bronchodilator salbutamol may also cause this toxidrome. It may appear very similar to the anticholinergic toxidrome, but is distinguished by ...
It can also cause headaches and gastrointestinal complications such as abdominal pain and nausea. A common but untrue belief is that the smoking of cocaine chemically breaks down tooth enamel and causes tooth decay. Cocaine can cause involuntary tooth grinding, known as bruxism, which can deteriorate tooth enamel and lead to gingivitis. [83]