What cause constricted pupils?

Constricted pupils, also known as miosis, can be caused by a variety of factors, including:

1. Bright Light: When exposed to bright light, the pupil naturally constricts to reduce the amount of light entering the eye.

2. Certain Medications: Some medications, such as opioid painkillers, can cause pupillary constriction as a side effect.

3. Neurological Disorders: Conditions like Horner's syndrome and oculomotor nerve palsy can disrupt the nerve pathways that control pupil size, leading to constriction.

4. Drugs and Substances: Certain drugs, including cocaine, amphetamines, and hallucinogens, can cause pupils to become constricted.

5. Head Injuries: Severe head injuries can damage the nerves or brain regions responsible for pupil control, resulting in constriction.

6. Parasympathetic Nerve Stimulation: Activation of the parasympathetic nervous system, through drugs or physiological responses, can cause pupillary constriction.

It's important to note that constricted pupils can be a normal physiological response to certain situations (like bright light) or a symptom of an underlying medical condition. If you experience sudden or persistent pupillary constriction along with other symptoms, it is advisable to consult a healthcare professional for proper diagnosis and treatment.