# Pain causing eyes to tear up

**URL:** <https://boards.straightdope.com/t/pain-causing-eyes-to-tear-up/480534>\
**Category:** Factual Questions\
**Created:** [January 9, 2009, 4:07pm UTC](https://boards.straightdope.com/t/pain-causing-eyes-to-tear-up/480534 "2009-01-09T16:07:20Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![HumanMonkeyGod](https://avatars.discourse-cdn.com/v4/letter/h/c67d28/32.png) [@HumanMonkeyGod](https://boards.straightdope.com/u/HumanMonkeyGod)\
**Post date:** [January 9, 2009, 4:07pm UTC](https://boards.straightdope.com/t/pain-causing-eyes-to-tear-up/480534/1 "2009-01-09T16:07:20Z")

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I’ve been wondering about this. I understand that asking “why” things evolved as they did is often foolish, but this one stumps me. Seems to me that if one experiences pain, it’s possible there is danger (and more pain) to follow, so how does being temporarily blinded help?

I ask as someone whose eyes seem to well up with little provocation - at pain levels that don’t cause much mental discomfort at all.

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**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\
**Post date:** [January 9, 2009, 5:13pm UTC](https://boards.straightdope.com/t/pain-causing-eyes-to-tear-up/480534/2 "2009-01-09T17:13:37Z")

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My eyes well up from pain more if the pain is nearby, like the nose or mouth or cheek. This could be part of the same reaction that tears up when some bit of dirt gets into the eye. Probably, in general and over the generations, it is helpful to have a rinsing action in the eyes if anything in that neighborhood is disturbed; more helpful than not, anyway.

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**Author:** ![HumanMonkeyGod](https://avatars.discourse-cdn.com/v4/letter/h/c67d28/32.png) [@HumanMonkeyGod](https://boards.straightdope.com/u/HumanMonkeyGod)\
**Post date:** [January 13, 2009, 4:58pm UTC](https://boards.straightdope.com/t/pain-causing-eyes-to-tear-up/480534/3 "2009-01-13T16:58:10Z")

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Yeah I meant to include that this mostly regarded facial sort of pain. The sort of scenario I was imagining was some distant forebearer being chased through the forest by a large hungry carnivore, hapless runner rounds a tree and bashes his forehead into a low branch. Eyes weep, human stumbles about in mild pain but near total blindness and twists his foot on a root, minutes later to make a teary meal.

But I guess that just didn’t happen (much). The eye-rinsing mechanism sounds valid though.

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**Author:** ![Max\_Torque](https://avatars.discourse-cdn.com/v4/letter/m/e9bcb4/32.png) [@Max\_Torque](https://boards.straightdope.com/u/Max_Torque)\
**Post date:** [January 13, 2009, 7:58pm UTC](https://boards.straightdope.com/t/pain-causing-eyes-to-tear-up/480534/4 "2009-01-13T19:58:22Z")

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WAG, but, I assumed it was just due to an involuntary muscle contraction, just like the general “cringe” of pain that the rest of your body performs, although with the face I suppose it’s more of a “wince”. The lacrimal gland gets squeezed by the involuntary contraction, tears are forced out, and the result is watery eyes.

Evolution doesn’t mean there’s a purpose for everything. Some stuff is just the unforeseen side-effect of something that actually _does_ have a purpose.

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**Author:** ![sjc](https://avatars.discourse-cdn.com/v4/letter/s/e5b9ba/32.png) [@sjc](https://boards.straightdope.com/u/sjc)\
**Post date:** [January 13, 2009, 9:24pm UTC](https://boards.straightdope.com/t/pain-causing-eyes-to-tear-up/480534/5 "2009-01-13T21:24:25Z")

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At first I thought the title read “Pa **l** in causing eyes to tear up”.