Miosis is the constriction of the pupil. It’s the opposite of mydriasis 😊.

Common causes:

1. Bright light
2. Medications: Opioids (e.g., morphine), eye drops (e.g., pilocarpine)
3. Conditions: Horner’s syndrome, iritis, or neurological disorders
4. Aging
5. Substance use: Certain drugs (e.g., heroin)

Effects:

1. Reduced light entry → dim vision in low light
2. Increased depth of field (improved near vision)
3. Headache or eye strain