# Do cats die if you put razors in their eyes? **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [October 10, 2005, 2:34am UTC](https://boards.straightdope.com/t/do-cats-die-if-you-put-razors-in-their-eyes/325487 "2005-10-10T02:34:00Z")\ **Posts on this page:** 5\ **Page:** 3
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [October 12, 2005, 1:46am UTC](https://boards.straightdope.com/t/do-cats-die-if-you-put-razors-in-their-eyes/325487/41 "2005-10-12T01:46:31Z")
> [@CynicalGabe](#): > > When’s Q.E.D going to return to tell me if my laser assertions are correct? Sorry. I forgot all about this thread, and then they moved it on me. Anyway, it’s a rather complicated issue. If we assume we are dealing with red lasers at the typical diode laser wavelength of about 680 nm, then the 30,000 second figure expressed in your camera’s manual means the laser is not capable of exceeding the Maximum Permissible Exposure (MPE) for a laser of this wavelength of about 30 x 10[sup]-6[/sup] mW/cm[sup]2[/sup], as measured at the cornea (see Table III:6-6 [here](http://www.safety.vanderbilt.edu/pdf/laser_exposure_limits.pdf) - PDF document). However, this is not a class rating, but an _exposure_ rating, and applies to all laser classes. It is dependent only upon wavelength. Your manual is incorrect in this regard. The _class_ is based upon a figure called Accessible Emission Limit (AEL): > [@](#): > > FDA Long-Term Exposure Limits. The FDA/CDRH Federal Laser Product Performance Standard (FLPPS) assumes a linearly additive biological effect for exposures to visible light between 10 and 10[sup]4[/sup] seconds (2.8 hours). The standard accepts that a cumulative radiant energy exposure of 3.85 millijoules (mJ) will not cause a biological effect. Hence a 10-second total accumulated exposure corresponds to an average power entering a 7-mm aperture of 385 microwatts (uW). For an exposure of 10[sup]4[/sup] seconds, the average power would be 0.385 uW. In the FLPPS, the power level of 0.385 uW is referred to as the Class I Accessible Emission Limit (AEL) for a visible CW laser. Since your camera’s laser focussing system is rated for 30,000 seconds of exposure (occupational exposure, i.e., approximately 8 hours, the length of a typical workday), the average power as measured at the cornea cannot exceed 0.128 uW. Your camera can meet this specification, since the beam is dispersed. Other devices, such as laser printers, can only meet the specification for Class I if the beam is entirely contained within the device and protected by interlocks, as I stated earlier. So, you get partial credit. However, no laser pointer can possibly meet the Class I specification. It’s not possible. ---
**Author:** ![CynicalGabe](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@CynicalGabe](https://boards.straightdope.com/u/CynicalGabe)\ **Post date:** [October 12, 2005, 2:15am UTC](https://boards.straightdope.com/t/do-cats-die-if-you-put-razors-in-their-eyes/325487/42 "2005-10-12T02:15:40Z")
> [@Q.E.D.](#): > > Your camera can meet this specification, since the beam is dispersed. Other devices, such as laser printers, can only meet the specification for Class I if the beam is entirely contained within the device and protected by interlocks, as I stated earlier. So, you get partial credit. Ahh. I stand corrected. > [@](#): > > However, no laser pointer can possibly meet the Class I specification. It’s not possible. That sounds like a challenge. 😉 /scurries off to mad-scientist lab ---
**Author:** ![Zebra](https://avatars.discourse-cdn.com/v4/letter/z/c0e974/32.png) [@Zebra](https://boards.straightdope.com/u/Zebra)\ **Post date:** [October 12, 2005, 4:18am UTC](https://boards.straightdope.com/t/do-cats-die-if-you-put-razors-in-their-eyes/325487/43 "2005-10-12T04:18:09Z")
> [@vetbridge](#): > > (Bold text via me.) > > Gotta respectfully disagree, having done just that. I have removed dermoids from the corneal surface of a cat’s eye using a razor blade piece broken off using an instrument called a Castroviejo Blade Breaker (cite: [http://www.delasco.com/pcat/2/GSInstruments/RBH13C/RBH13C/](http://www.delasco.com/pcat/2/GSInstruments/RBH13C/RBH13C/)) > > Here is a picture of one such tumor: > [Website Disabled](http://www.catvet.homestead.com/Dermoid.html) > > Note, while it is possible to stick a razor in the eye of a cat, it should be done under a general anesthetic using appropriate surgical technique. I am NOT looking at that link. ---
**Author:** ![InternetLegend](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/internetlegend/32/13154_2.png) [@InternetLegend](https://boards.straightdope.com/u/InternetLegend)\ **Post date:** [October 12, 2005, 6:34am UTC](https://boards.straightdope.com/t/do-cats-die-if-you-put-razors-in-their-eyes/325487/44 "2005-10-12T06:34:38Z")
> [@ntucker](#): > > And to think all these years I thought it was the cat’s **own** curiosity that killed it… I just have to say that this comment inspired me to tell every member of my immediate family about this thread, just to use your punchline. And we have all laughed and laughed and laughed. _I’m sure even the cats would have laughed, had they been able._ ---
**Author:** ![picunurse](https://avatars.discourse-cdn.com/v4/letter/p/7bcc69/32.png) [@picunurse](https://boards.straightdope.com/u/picunurse)\ **Post date:** [October 12, 2005, 6:50am UTC](https://boards.straightdope.com/t/do-cats-die-if-you-put-razors-in-their-eyes/325487/45 "2005-10-12T06:50:59Z")
> [@sciguy](#): > > Is this “hypothetical” experiment just a tail transplant, or attaching the stump of CatA to CatB to create a Pushmeow-Pullmew? The anti-rejection drugs are pretty expensive… 😃 [Previous page](https://boards.straightdope.com/t/do-cats-die-if-you-put-razors-in-their-eyes/325487.md?page=2)