What is Miosis?

What Is Miosis? What are some of the causes?

Miosis is the excessive constriction of the pupil of the eye.  Miosis can be caused by a bacterial infection in your brain that comes from untreated syphilis, a sexually transmitted disease.

What else can cause Miosis?

Miosis can also come from a major lack of vitamin D. There are two main ways to get vitamin D. Exposing your bare skin to the sunlight or taking a supplements.
You can’t really get the right amount of vitamin D your body needs from foods. Fatty fish like tuna, mackerel and salmon all have vitamin D. Orange juice, soy milk,beef liver, cheese and egg yolks all have Vitamin D, but ultraviolet B rays, sunlight, is the most natural.
Farsightedness, when you have trouble seeing things close up, this too can cause Miosis.  And Miosis can be caused by drug use. Using opiodis or opiates can cause your pupils to constrict excessively. Benzodiazepines can induce miosis. The sedation caused by benzodiazepines does this. Their atrophine-like effect on the iris is predicted to lead to mydriasis or dilation of the pupil of the eye. Anti-hypertension medications are other drugs that can cause miosis. These drugs could influence the parasympathetic nervous system to constrict the pupil by it’s control over the circular muscle.

The parasympathetic nervous system and Miosis

The parasympathetic nervous system is one of three divisions of the autonomic nervous system. Sometimes called the rest and digest system, the parasympathetic system conserves energy as it slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles in the gastrointestinal tract.
The sphincter is innervated by (signaled by nerves of) the parasympathetic nervous system, and the dilator by the sympathetic nervous system. Sympathetic stimulation of the adrenergic receptors causes the contraction of the radial muscle or the subsequent dilation of the pupil.  Proper stimulation of the parasympathetic nervous system can reverse miosis, taking the pupil from contracted to dilated.