Q&A for How to Dilate or Shrink Your Pupils on Command

There are two sheets of circular muscles in the iris, one that expands to dilate the pupil in low light and one that contracts to constrict it in bright light.

The most common reason is that the lighting is dark or dimly lit, but there are other reasons why your pupils might dilate. There are certain prescription drugs, such as atropine, antihistamines, decongestants, tricyclic antidepressants, botox, and certain anti-seizure drugs that can cause this. Many illegal drugs are also known to cause dilated pupils, including, cocaine, amphetamines, psychedelics and ecstasy. Sometimes a head injury, a stroke or another brain disorder can cause pupils to dilate as well as certain injuries to the eye itself. Sometimes pupils can dilate for no specific reason, even for several days, but not be dangerous or indicate a more serious condition (known as benign episodic unilateral mydriasis).

Explain to them that you are on a medicine that has that side effect.

Test it out by looking in a mirror as you try to change them.

It depends on eye color. If the iris is brown, especially very dark brown, it won’t be that noticeable. If the iris is a lighter color, then people may notice it. If you wear color contacts, no one will notice.

Unless you have perfect eye control, this is impossible.

Yes, it can definitely harm your vision. A lot of these techniques, if done repeatedly, put a lot of strain on your eyes and can hurt your eyesight over time.

Yes.

No-––antibiotic drops do not penetrate deeply enough through the protective layers of the eye to affect pupillary functions.

That depends. If you're in a dark then yes, and if you're in a bright room then no. That's a tricky question because it really depends on what it looks like around you.