# Pupils



## Explorer127 (Mar 25, 2009)

Why do people's pupils constrict when they are sleeping? Generally, does trauma to the eye cause constriction or dialation? Or does it vary with different pts? Will head injuries ever cause pupils to constrict instead of dilate?


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## rhan101277 (Mar 25, 2009)

As you may know, the eyes are controlled by the optic nerves which come from your brain.  When pressure is exerted on these nerves due to trauma it can cause them not to function correctly.  One eye could be dilated while the other is constricted and vice versa.

The eye is a very complicated subject as I learned in anatomy.

Good reading.

http://en.wikipedia.org/wiki/Rhodopsin

http://en.wikipedia.org/wiki/Optic_nerve

As far as why your pupils do that during your sleep.  Its hard to answer, it has to do with the nervous system and requires some understanding of how it works to make any sense.  More reading..

http://universe-review.ca/R10-16-ANS.htm


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## AJ Hidell (Mar 25, 2009)

rhan101277 said:


> As far as why your pupils do that during your sleep.  Its hard to answer...


Not that hard.  In life, what neurochemical response makes pupils dilate (as well as increased pulse, respiratory rate, sweating)?  Now, at what time would that neurochemical response be least active and least likely to occur?

There ya go.


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## mikeN (Mar 25, 2009)

I'm takig a wild guess and saying that is your parasympathetic system kicking in and taking over. Just a guess and still doesn't explain much.


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## frdude1000 (Apr 8, 2009)

Yes, any abnormality in the size, inequality, or dialation/constriction is abnormal.

From emsresponder.com:

# Pupil is the black center of the eye - Amount of light that enters the eye changes the size
# Evaluate pupils for

    * Size
    * Equality
          o Both equal in size
          o Causes of unequal pupils: stroke, head injury, eye injury, artificial eye
    * Reactivity
          o Reacting to light by changing sizes
          o Causes for lack of reactivity: drugs, lack of oxygen to the brain

# Dilated Pupils

    * Become larger
    * Allow more light into the eye
    * Causes for dilated pupils: fright, blood loss, drugs, treatment with eye drops

# Constricted Pupils

    * Become smaller
    * Large amount of light gets into the eye


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## Moxiy (Apr 19, 2009)

mikeN said:


> I'm takig a wild guess and saying that is your parasympathetic system kicking in and taking over. Just a guess and still doesn't explain much.



This is probably a good guess.

If the occular motor nerve is depressed, etc, there is a good change you will see unequal pupils.


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## MSDeltaFlt (Apr 19, 2009)

Explorer127 said:


> *Why do people's pupils constrict when they are sleeping*? Generally, does trauma to the eye cause constriction or dialation? Or does it vary with different pts? Will head injuries ever cause pupils to constrict instead of dilate?


 


AJ Hidell said:


> *Not that hard. In life, what neurochemical response makes pupils dilate (as well as increased pulse, respiratory rate, sweating)*? Now, at what time would that neurochemical response be least active and least likely to occur?
> 
> There ya go.


 
Ockham's Razor:  All things being equal, the simplest answer is usually the best one.

Using that statement, the reason *why* pupils constrict during sleep should also be simple.

When you are awake and your *adrenaline* is kicking in (due to fear - a primitive response), your heart rate increases and your blood pressure increases to take on the demands of what your body is about to have to do.  Your hands and feet will sweat in to increase your grip.  Your *pupils will dilate* in order to take in as much visual detail as possible so you won't miss anything.

When you are sleeping, the opposite is also true.  Your HR and BP will lower because your are resting.  Your hands and feet will dry because they will not need to grip anything.  Your pupils will constrict because they will not need to see anything because they will be closed for a long period of time.


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## Melclin (May 9, 2009)

frdude1000 said:


> Yes, any abnormality ... is abnormal.



Really? I would never have known.


I kid , I kid.


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## mycrofft (May 10, 2009)

*I didn't know they constricted.*

Hard to tell since the eyes roll up normally when you sleep. 
Except for A&P students in the first two rows in class.


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## mace85 (May 27, 2009)

mycrofft said:


> Hard to tell since the eyes roll up normally when you sleep.
> Except for A&P students in the first two rows in class.



Ok, now that's funny.


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## mycrofft (May 27, 2009)

*Even odder...the relaxed state of the iris is with dilated pupils.*

Hence it being a clinical sign that you're bar tab has devolved to your estate.

More frequently seen than acute head trauma as a cause for pupillary changes are emotion (internal chemicals), external chemicals (toxins, drugs), old trauma or surgery to the eye (including iridectomy for closed-angle glaucoma leading to a "keyhole" iris).
Oh, yes....also, artificial cosmetis eyes and maybe cosmetic contact lenses can affect what you see in the pt's baby blues.


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