The opposite of mydriasis is miosis, which involves the constriction of the iris, leading to very small or pinpoint pupils.
Understanding Mydriasis and Miosis
Mydriasis and miosis refer to the dilation and constriction of the pupil, respectively. These changes in pupil size are controlled by muscles in the iris, responding to various stimuli such as light levels, medications, and emotional states.
| Feature | Mydriasis | Miosis |
|---|---|---|
| Pupil Size | Dilated (enlarged) | Constricted (small/pinpoint) |
| Iris Action | Iris muscles contract to dilate | Iris muscles contract to constrict |
| Common Causes | Darkness, drugs, fear | Bright light, opioids |
Key Differences and Related Conditions
-
Anisocoria: Mydriasis affecting only one pupil is called anisocoria.
-
Causes of Mydriasis: Can be caused by certain medications, eye drops, or underlying medical conditions.
-
Causes of Miosis: Often a result of bright light exposure or certain medications like opioids.
Reference: The opposite of mydriasis is called miosis and is when the iris constricts to cause very small or pinpoint pupils. Mydriasis can affect one pupil at a time or both at once. Mydriasis that affects only one eye is called anisocoria.
