Does Nicotine Dilate Pupils? (What Research Shows)

A look at how nicotine affects pupil size has been published in mainstream media, with some scientists and journalists claiming that people who use tobacco develop enlarged pupils, indicating that they are addicted or under the influence. Yet, the science is unclear.

There is no evidence that tobacco users have enlarged pupils, and it’s not very clear if tobacco use affects pupil size. Moreover, the size of pupils may not be a reliable sign of tobacco use, since the size of the pupil is affected by many factors, including light intensity.

Different lighting conditions can cause pupils to grow or shrink. Medication can also have an impact on the size of the pupil.

Mydriasis is the scientific name for pupils that enlarge. Miosis refers to when pupils get smaller. It is possible for both of these reactions to happen when a drug or substance enters the body.

Researchers have found that our pupils dilate when light levels change, when we need to focus on something closer, and when our eyes are responding to external or internal stimuli. For instance, your eyes dilate when you’re scared or excited.

Is Nicotine a Cholinergic Agonist or Antagonist?

There are two families of receptors, nicotinic and muscarinic. They get their names from the ligands that activate these receptors. Nicotine acts on nicotine receptors, while muscarinic receptors are activated by muscarine.

Signal transduction takes place through cholinergic receptors in the autonomic and somatic nervous systems. Because of their activation by acetylcholine, these receptors are called acetylcholine receptors.

To make it simple, nicotine is a cholinergic agonist. This means that it binds with the receptor and activates it.

Does Nicotine Constrict or Dilate Pupils?

Nicotine is the most commonly used addictive substance. The rate of its use has increased in the past several decades. The reasons for the increase in use have been attributed to the flexibility and relative social-acceptability of the substance.

The relationship between nicotinic acetylcholine receptor (nAChR) function and the development of smoking-related diseases is not well understood. Several clinical studies have shown that nicotine is a cholinergic agonist, which leads to the development of dependence and addiction.

In a study which included non-smokers and tobacco smokers, the size of pupils was measured after sham- and tobacco-smoking, respectively.

The study showed that compared to sham-smoking, pupillary constriction with tobacco was greater shortly after smoking one cigarette. However, this effect disappeared quickly and did not persist beyond 30 minutes.

This suggests that there may be some short-term effects of nicotine on pupil constriction.

How does nicotine affect pupils? Nicotine affects the pupils via its action on the parasympathetic nervous system. The parasympathetic nervous is responsible for the involuntary part of the autonomic nervous system. This includes things like heart rate, digestion, salivation, urination, defecation, etc.

When the parasympathetic nerves are stimulated, they signal the iris sphincter muscles to contract. When the parasympathetic nerve activity decreases, the signal is sent to the iris sphincter muscle, which then relaxes, and the pupil becomes larger.

This is why people who smoke tend to have smaller pupils than those who don’t smoke.

Taking Some Drugs Can Dilate Your Pupils

Drugs that affect your nervous system can make your pupils get dilated.

Cocaine causes dilation of the pupils, as well as other effects such as increased heart rate, sweating, nausea, vomiting, and hallucinations.

Methamphetamine causes dilation of the pupils, along with other effects such as increased blood pressure, anxiety, hyperactivity, muscle twitching, and dry mouth.

LSD causes dilation of the iris, and may cause other symptoms, such as hallucinations, confusion, and paranoia.

Marijuana causes dilation of the eye, but does not usually cause any other side-effects.

Marijuana causes dilation of the pupil, which is caused by hyperarousal of the nerves. This happens because of the chemical THC which is found in marijuana. There isn’t much research done on this topic, but it seems that people who smoke marijuana tend to have dilated pupils.

Is It True That Nicotine Causes Addiction?

This question has been debated for decades. Nicotine is a psychoactive drug that binds to the receptors of the cholinergic system in the brain.

Once it binds, it triggers the release of several neurotransmitters, including dopamine, adrenaline, and serotonin. All of these neurotransmitters have been implicated in the development of addiction.

How Long Does It Take for Nicotine to Affect the Pupil?

Once a person smokes, the effects of nicotine will be felt within the first minute. However, these effects will be short-lived, and then the effects will disappear.

Does the length of time it takes for the pupil to constrict or dilate affect how addictive the substance is? It’s not clear how the length of time it takes for the pupil to constrict or dilate affects the addictiveness of nicotine. The same amount of nicotine will produce different effects on the pupils if taken in different amounts of time.

It may also be related to the duration of smoking, and how much nicotine is absorbed in the blood.

However, there are no data available about the effect of the duration of smoking on the pupil response. There is a hypothesis that as people smoke more, they get progressively more addicted to nicotine and, therefore; they take longer to feel the effects. However, this is not supported by data.

Is there any effect of gender on the pupil response to nicotine? It’s not clear what role gender plays in the pupil response to nicotine.

The age of a person also plays a role. If someone is young, it may take longer for them to develop tolerance to nicotine. If someone is old, it may take less time for them to develop tolerance.

Don’t Smoke to Keep Your Eyes Healthy

The benefits of quitting smoking include allowing your eyes to heal and regenerate some cells, whether you use cigarettes or vape pens. Those who refrain from smoking for many years reduce their risk of many eye diseases. It will not be possible to eliminate the risk completely, since the effects of smoking persist for a long time following your cessation. However, cutting down the risk is well worth it.

A physician can help you quit smoking and stay sober if you’re a smoker. You can manage your risk of eye diseases by working with your optometrist or ophthalmologist.

Your eye doctor will watch for any signs of AMD, cataracts, glaucoma, or vision loss with an annual eye exam, no matter what your age is. There are a bunch of chronic eye conditions that can make your vision worse, but many of them can be treated. Stay on top of your eye health so you can keep your vision for years.

References:

https://pubmed.ncbi.nlm.nih.gov/10235421/

https://www.sciencedirect.com/science/article/abs/pii/S0167876020302166

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