# Checking eyes with an LED



## adamjh3 (Jun 4, 2010)

Question: Is checking someone's eyes (essentially just PERRL) with an LED - using only the spill, of course - harmful? I've heard arguments for both sides, and I've researched and come up with conflicting information. 

Thanks

-Adam


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## EMSLaw (Jun 4, 2010)

I'm going to probably regret this answer, but...

If manufacturers like ADC sell LED penlights, I can't imagine they are harmful to the patient.


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## Sandog (Jun 4, 2010)

As a former Field applications Engineer I can tell you this. LED's come in a variety of flavors ranging from red, green, blue, yellow to white. Brightness levels range from ultra bright (which may hurt eyes to look at) to not so bright. Controlling the light intensity of an LED is a simple matter of a single series resistor and can be adjusted in such a way as the light intensity is not harmful to the human eye. I am sure there are LED penlights specifically designed for medical use where the luminosity is corrected. 

I would suggest that you use a LED penlight designed for medical use and not one from Home Depot.

The benefit of LED is long battery life and reliability as compared to an incandescent bulb.


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## adamjh3 (Jun 4, 2010)

Sandog said:


> As a former Field applications Engineer I can tell you this. LED's come in a variety of flavors ranging from red, green, blue, yellow to white. Brightness levels range from ultra bright (which may hurt eyes to look at) to not so bright. Controlling the light intensity of an LED is a simple matter of a single series resistor and can be adjusted in such a way as the light intensity is not harmful to the human eye. I am sure there are LED penlights specifically designed for medical use where the luminosity is corrected.
> 
> I would suggest that you use a LED penlight designed for medical use and not one from Home Depot.
> 
> The benefit of LED is long battery life and reliability as compared to an incandescent bulb.



I'm a budding flashaholic, which is why this topic came up. 

One of my friends (whom does not work in the medical field) also brought up the issue of color retention of an incan vs. an LED. I think I'm just sticking with an incan, for now.


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## Sandog (Jun 4, 2010)

Okay, I have to ask, what is a flashoholic?


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## MRE (Jun 4, 2010)

Sandog said:


> Okay, I have to ask, what is a flashoholic?



Someone with an obsession with flashlights and/or lighting in general.  I may have been accused once or twice.  


I carry a surefire e2e incandescent which could burn the eyes right out of your head, but I have used the wide spill to (carefully) check pupils before.  I have also used LEDs.  In my opinion an LED light with a nice smooth pattern is superior to those 5 cent disposable pupil penlights most ambulances stock.  They are quite often too dim and the artifacts in the light can make it very difficult to see any detail in the eye.  

As long as the LED is close to regular white light, the eye should react about the same.  The biggest difference between LEDs and incandescents is that incandescents produce a lot of infrared light in addition to visible light and LEDs don't.

Especially with cooler (more blue) LEDs, colors may not be as easy to see as with incandescents, but there are many LEDs available now that are not as susceptible to this.


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## mcdonl (Jun 4, 2010)

W1IM said:


> Someone with an obsession with flashlights and/or lighting in general.  I may have been accused once or twice.
> 
> I carry a surefire e2e incandescent which could burn the eyes right out of your head, but I have used the wide spill to (carefully) check pupils before



I have a surefire on either side of my helmet, on my XD and my AR but I could not imagine pointing one of those at a patients eyes!

I guess it would work just fine but would be pretty blinding. Hi, my name is mcdonl... I am a flashaholic too


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## Fox800 (Jun 4, 2010)

The best way to be sure is to just carry a legit, actual penlight with the pupil gauge on the side. That way you're not "eyeballing" it (har har) when you guesstimate pupil sizes for your narrative.

If you're using a Surefire to check pupils you probably deserve a smack on the back of the head.

This post brought to you my Captain Obvious.


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## mycrofft (Jun 4, 2010)

*Hi, I'm Mycrofft and I'm a Flashoholic too!*

...and I thought my malady was without a name! I give flashlights for Christmas!

I was never fast enough to shine the little penlight in their eyes, then whip it up to measure their pupils. Oh, wait, you measure them in ambient light...:blush:

The LED's on most flashlights are actinic (lots of blue and sometime into long wave UV), and not much red or IR. Shine one into your eye and see what it is like.B)
Checking for redness of the conjunctiva, the throat, etc. is not well done with them, blood can be missed. 

Now...I _was_ using a nine-unit LED for pt assessment and seeing in the dark, but if I needed good color vision I pulled out my four dollar, two-AA light with the added-on Krypton bulb. I checked pupils with the sidewash of the LED but very quickly, and with adequate lighting around me to see the pupils after my flash had passed.


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## reaper (Jun 4, 2010)

Fox800 said:


> The best way to be sure is to just carry a legit, actual penlight with the pupil gauge on the side. That way you're not "eyeballing" it (har har) when you guesstimate pupil sizes for your narrative.
> 
> If you're using a Surefire to check pupils you probably deserve a smack on the back of the head.
> 
> This post brought to you my Captain Obvious.



And why would this be?

If you know how to correctly assess pupils, you could use a spotlight!


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## Fox800 (Jun 4, 2010)

Yes, lets use a 2,000,000 candlepower unit to check pupils. Hope you dont trip or get pushed while you're doing it...ouch for your patient. Lets also use Mac/Miller 4's on babies because we can! If you can make it work it's fine, right?

No.


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## reaper (Jun 4, 2010)

exactly. The light should never be shined directly into the eye. It should be brought in from the side, until the light starts to hit the pupil.


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## adamjh3 (Jun 4, 2010)

reaper said:


> exactly. The light should never be shined directly into the eye. It should be brought in from the side, until the light starts to hit the pupil.




True, but I've tried it on myself with both a low low incan (mag solitaire) and a low low LED (Quark AA on moonlight mode) and the LED caused some discomfort, even with just the spill of the beam. But that could be a biased study.


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## Sandog (Jun 4, 2010)

mycrofft said:


> The LED's on most flashlights are actinic (lots of blue and sometime into long wave UV), and not much red or IR. Shine one into your eye and see what it is like.B)
> Checking for redness of the conjunctiva, the throat, etc. is not well done with them, blood can be missed.



Perhaps this may be true for a penlight purchased at your local hardware outlet, but true white LED's as would be used for medical use produce an even distribution of RGB as can be seen in the graph below, taken from an LED datasheet. Considering that the human eye only has receptors for RGB, other colors are irrelevant.


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## clibb (Jun 4, 2010)

I bought an LED penlight from Wal-Mart for $3.06 to be exact, that's with the tax included  .
I liked it because it was cheaper then a regular pen light. But, this one I'll use for tying  flies in the dark and if someone would happen to fall on their head or get a concussion when I'm out camping or fishing. For when I'm on the bus, I'll use the regular penlights they have there.


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## Veneficus (Jun 4, 2010)

Fox800 said:


> Yes, lets use a 2,000,000 candlepower unit to check pupils. Hope you dont trip or get pushed while you're doing it...ouch for your patient. Lets also use Mac/Miller 4's on babies because we can! If you can make it work it's fine, right?
> 
> No.



You use a laryngoscope to tube an infant?


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## mycrofft (Jun 4, 2010)

*Color receptors are nearly irrelevant.*

We don't have receptors for short wave UV and it will actually injure cells, including the cornea and the lens, given enough lumens/minutes. 

The pupillary response can be elicited even in animals with few color receptors because the black and white receptors (the ones we used to use for TV) are all you need. Oh, and intact neural pathways too.

Nice that they are getting the LED's tuned in better though. Now they need to outlaw them on headlights.


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## Sandog (Jun 4, 2010)

I am not aware of LED's giving off UV light, care to share this info? Of couse they do make UV lights, but this was done intentionally. 

I agree, those LED headlights are obnoxious and blinding at night.


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## Fox800 (Jun 4, 2010)

Veneficus said:


> You use a laryngoscope to tube an infant?



I suppose you could get by without but yes...Miller 0 would fit the bill methinks.


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## mycrofft (Jun 4, 2010)

*uv led*

http://www.google.com/search?sourceid=navclient&ie=UTF-8&rlz=1T4DKUS_enUS253US253&q=ultraviolet+LED
I have one I boght at Target that makes Fluorescin light up just fine.


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## Sandog (Jun 4, 2010)

Yes there are LED's that emit UV light but they are specifically designed for that purpose. Your link does not show that standard LED's emit UV light and I doubt that you will find a link that shows they do. I find it hard to believe that you get something to fluoresce from a standard LED, but who am I to argue.


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## webster44 (Jun 9, 2010)

I use the Streamlight Stylus

http://www.streamlight.com/documents/fact-sheet/120.pdf

I think I was about $10 or so. I like mainly because it slips into my shoulder pocket next to my pen, and has a tailcap switch. Its also bright enough to illuminate all sorts of other things.

I know that someday I'll lose it. But with it only costing 10 bucks i'm ok with that.


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## TransportJockey (Jun 9, 2010)

I picked up a little metal Rayovac LED penlight from walmart. Works pretty well to light up things and the check pupils. Was only like $2


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## Sasha (Jun 9, 2010)

I keep some kind of flashlight in my bag for various reasons, last night neither my partner or I couldn't find our penlights and I used the flashlight to check pupils. Regular penlights are ideal but not absolutely necessarry.


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## JJR512 (Sep 21, 2010)

webster44 said:


> I use the Streamlight Stylus
> 
> http://www.streamlight.com/documents/fact-sheet/120.pdf
> 
> ...



Sorry to dig up an older thread, but I came here tonight expressly for the purpose of enquiring about the Streamlight Stylus, and whether it was too bright or just right for diagnostic purposes (checking pupil response).

The light I have now is a Streamlight Microstream, rated at 20 lumens. It's too bright for a diagnostic penlight. The Stylus is rated at 10 lumens. But in its reviews at Galls, one person says it's bright enough to clear a room if the main light fails, another person says it's bright enough to blind a suspect if he becomes combative (this guy uses it in field sobriety tests to have the suspect follow the light sideways, looking for jerking motion of the eyes). Out of all the reviews at Galls, I believe one person said they've used it for EMS patient assessment, but even that person said it was a bright light.

Apparently, at least one person here feels it is acceptable for EMS. Now, in this thread, a lot of people have mentioned using LED lights, and some have mentioned using general-purpose LED flashlights vs. using actual medical LED lights, but until this mention of the Streamlight Stylus, I don't think I noticed any brands or model names mentioned for specific-purpose lights. So I'm wondering if anyone else has experience with the Streamlight Stylus, specifically whether it is too bright or just right for EMS diagnostic use, or what other brands/models are worth considering?


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## adamjh3 (Sep 21, 2010)

JJR512 said:


> [berevity]  ...or what other brands/models are worth considering?



I carry a 4sevens Preon 1 with me now. Comes on at 1.8 lumens, but can go up to 80 lumens if you need it. Works very well for checking reactivity, none too bright, and very handy for making sure I have everything in my backpack after EOW.

EDIT: I also added the clicky tailcap for $11, well worth it


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## EMTventually (Jul 2, 2020)

adamjh3 said:


> I'm a budding flashaholic, which is why this topic came up.
> 
> One of my friends (whom does not work in the medical field) also brought up the issue of color retention of an incan vs. an LED. I think I'm just sticking with an incan, for now.


 im a bit of one too, lol. im pretty much all OLight, mostly bc of quality, but definitely bc they have some unique color ways and styles too. M2R Warrior on my belt, and I have a Baton 1 that I keep with me bc its smaller and I can attatch it to my hat and use it as a headlamp if needed. thats come sooooooo in handy lol.


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## hometownmedic5 (Jul 2, 2020)

EMTventually said:


> im a bit of one too, lol. im pretty much all OLight, mostly bc of quality, but definitely bc they have some unique color ways and styles too. M2R Warrior on my belt, and I have a Baton 1 that I keep with me bc its smaller and I can attatch it to my hat and use it as a headlamp if needed. thats come sooooooo in handy lol.



And todays thread CPR award goes too......


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## ffemt8978 (Jul 2, 2020)

Closed for necroposting.


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