# Can those keychain lazers damage your eyes? **URL:** \ **Category:** Factual Questions\ **Created:** [August 26, 2002, 12:55am UTC](https://boards.straightdope.com/t/can-those-keychain-lazers-damage-your-eyes/125541 "2002-08-26T00:55:53Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![aha](https://avatars.discourse-cdn.com/v4/letter/a/eada6e/32.png) [@aha](https://boards.straightdope.com/u/aha)\ **Post date:** [August 26, 2002, 12:55am UTC](https://boards.straightdope.com/t/can-those-keychain-lazers-damage-your-eyes/125541/1 "2002-08-26T00:55:53Z")
I think they are called Diode lazers. If they can seriously damage your eyes they why are they available to small children? My son came home from a rodeo this weekend with one. He’s 12 years old. Of course fireworks could damage your eyes too but not in such a covert way. I was just wondering how much exposer it would take before eye damage occurred? ---
**Author:** ![pkbites](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pkbites/32/204_2.png) [@pkbites](https://boards.straightdope.com/u/pkbites)\ **Post date:** [August 26, 2002, 1:22am UTC](https://boards.straightdope.com/t/can-those-keychain-lazers-damage-your-eyes/125541/2 "2002-08-26T01:22:47Z")
In many areas it’s illegal for minors to posses laser pointers. In Wisconsin it’s a crime to point a laser beam at a police officer. From what I’ve read, constant exposure to one can harm the eye, but for how long one must be exposed I do not know. ---
**Author:** ![aha](https://avatars.discourse-cdn.com/v4/letter/a/eada6e/32.png) [@aha](https://boards.straightdope.com/u/aha)\ **Post date:** [August 26, 2002, 1:29am UTC](https://boards.straightdope.com/t/can-those-keychain-lazers-damage-your-eyes/125541/3 "2002-08-26T01:29:59Z")
Lasers! Of course that’s the proper spelling. The one my son had said Lazer Ray. A brand name that stuck in my head apparently. ---
**Author:** ![Church\_Key\_Kid](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@Church\_Key\_Kid](https://boards.straightdope.com/u/Church_Key_Kid)\ **Post date:** [August 26, 2002, 1:37am UTC](https://boards.straightdope.com/t/can-those-keychain-lazers-damage-your-eyes/125541/4 "2002-08-26T01:37:47Z")
From [http://www.princeton.edu/~ehs/laserpointer.html](http://www.princeton.edu/~ehs/laserpointer.html) > [@](#): > > Potential Hazards > > The hazards of laser pointers are limited to the eye. Although with most visible lasers, the largest concern is potential damage to the retina, most laser pointers are not likely to cause retinal damage. The possible exception might be the green light lasers described above. > > The most likely effects from exposure to viewing the beam from a laser pointer are afterimage, flashblindness and glare. Flashblindness is temporary vision impairment after viewing a bright light. This is similar to looking directly at a flashbulb when having a picture taken. The impairment may last several minutes. > > Afterimage is the perception of spots in the field of vision. This can be distracting and annoying, and may last several minutes, although there have been reports of afterimages lasting several days. > > Glare is a reduction or complete loss of visibility in the central field of vision while being exposed to the direct or scattered beam. This is similar to viewing oncoming headlights on a dark night. Once the beam is out of the field of vision, the glare ceases. While this does not pose a hazard to the eye, it can cause serious distraction and outrage. Glare can be exacerbated when the beam is reflected from a mirror-like surface. But still, better not risk it anyways. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [August 26, 2002, 2:22am UTC](https://boards.straightdope.com/t/can-those-keychain-lazers-damage-your-eyes/125541/5 "2002-08-26T02:22:54Z")
This question has come up on the Board before. My recollection, from undergrad physics lab, was that exposure to a 1/4 mW HeNe laser was roughly equivalent to staring at the sun. Someone posted a link to a site that showed that the exposure is on the order of 100 times greater than staring at the sun. I crunched the numbers and couldn’t find a mistake, so I guess m recollection is off. A red diode laser “pointer” is roughly the same wavelength and output power. Your eye will respond to bright light by closing down your iris rapidly and closing the lid. I’ve heard stories that forty years ago people aligned lasers by looking down the barrel as they tinkered with the mirrors, relying on this self-protection to kick in. (Kids, _DO NOT_ try this at home!) It doesn’t always work. Some folk who work with high-energy lasers end up with zapped spots on their retinas. I doubt if you could seriously injure yoursel or someone else with a laser pointed withot working t it, but don’t go looking down he barrel or pointing it at anyone else. Save those things for actually pointing at things you’e lecturing about, or for playing with cats (don’t shine it in the cat’ eyes, either). And if you shine it at a movie screen – even if the movie is **Signs** – you deserve a punch n the nose. ---
**Author:** ![kaylasdad99](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kaylasdad99/32/3398_2.png) [@kaylasdad99](https://boards.straightdope.com/u/kaylasdad99)\ **Post date:** [August 26, 2002, 2:37am UTC](https://boards.straightdope.com/t/can-those-keychain-lazers-damage-your-eyes/125541/6 "2002-08-26T02:37:44Z")
Well, yes, it’s rude, of course, but it’s not really **dangerous** , is it? I mean, it’s only _metaphorically_ a silver screen, right? Heh. Anyway, **aha** , the eye haxard presented by the laser is going to be a function of several factors. [Here are some of them.](http://www.jlab.org/ehs/manual/EHSbook-454.html)