Because I am using one as a christmas tree decoration and people look straight into it every day.

7 Answers 7


Unless the mouse is labelled as a class 2 laser device, then it will not cause damage to your eyes. Most (possibly all) mice are either not lasers or class 1 laser devices, which are safe under all conditions, and do not require labelling.

If you want to know a lot more detail, there is a company called Broadcom Inc. (formerly Avago) which owns lots of patents in the this area. They have produced a detailed document covering aspects of safety with regard to optical and laser mice [PDF].


It will deplete the pigments in the cells of your retina where the light falls, but it doesn't contain enough energy to actually cause any lasting damage.


Well, I did spend some time experimenting with this few years ago.

I noticed that after spending several minutes staring directly at mouse LED at close range (as in 1-2 cm), the way I perceive colors changes. It resets back to normal after few minutes of not staring into the mouse, and as far as I can see, there was no permanent damage.

  • 2
    I think you'll find that happens with any coloured light - even with the different colours of "white" light, like the 3500K orangeish light from an electric lightbulb compared with the 5400K bluish light from the sun.
    – stib
    Dec 15, 2010 at 9:50
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    Cool! I can see colors and hear the grass grow. And DEA can't say anything 'cause it is the LED in my mouse's belly. ;-)
    – Aki
    Dec 15, 2010 at 9:50
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    You (over)stimulate the receptors for a specific color in your eye. When you look e.g. at a grey/white object afterwards, they are desensitized for a while, and you only perceive the colors from the other receptors (don't quote me on that, it's been a while since I read about it), so you see the opposite color (like yellow/blue). Perception is a funny thing, try googling for Adelson's checker shadow illusion, or the Hermann grid illusion.
    – Daniel Beck
    Dec 15, 2010 at 11:15
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    Please do not look into the laser with your remaining good eye. ;) Dec 17, 2010 at 20:12
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    "As far as I can see", good one :D !
    – Bertvan
    Feb 28, 2013 at 13:28

I don't think the LED is powerful enough anyway. You may get blurry eye for a few moments but you can get that just by looking at a bright light bulb for a duration. Your retina can get a little bit tired if staring in it for too long but this is all from the strong light. And it is not infra-red. Humans cannot see infra-red light. It is visible red which is higher in frequency.


No, unless you have a infrared laser led but I guess invisible beams are not the best christmas tree decoration ... ;-)

  • Wavelength effect what kinds of damage a bright light can do, but all wavelengths can be dangerous. Intensity is the single most relevant metric. Dec 15, 2010 at 15:58
  • I agree with that but you are missing my point. All laser mice I'm aware of are in the IR spectrum so there is no chance the question is about them. You unlikely use IR lights to decorate a christmas tree.
    – jlliagre
    Dec 15, 2010 at 16:55

Point source emissions such as lasers and LEDs are generally not good for your eyes.


And if LEDs are bad for your eyes, I'm not sure what makes a class 1 laser less harmful.

Best to avoid looking directly at it.

  • That page (apart from misleadingly mixing different arguments) discusses "white" LED lightbulbs, compared to incandescent ones. This question is about an optical mouse - never seen one using white light... Apr 10, 2021 at 18:07

It can damage your eyes, but not in an immediate or immediately noticeable way. The damage to the cells on retinas will be accumulated and permanent, but there are tons of photoreceptor cells on retinas. A relatively small number of dead/degraded cells at a time, combined with the brain's compensation mechanism, might not be noticeable immediately without specific testing. However, the vision loss/degradation is real, and it will eventually become disabling if accumulated enough; this is not the only source of damage, so why add unnecessary damage to your eyes when it's avoidable?

"The blink reflex and aversion responses are protective mechanisms against injury caused by devices with a radiation output of less than 1 mW (2). This class of laser only causes damage if the exposure time exceeds 0.25 s, which approximately corresponds to the time lag of the natural blink reflex (according to DIN EN 60825–1). However, only part of the population can be expected to have this blink reflex, meaning that these natural protective mechanisms are inadequate (3)." (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5754573/)

Degradation/damage to the photoreceptor cells on retina won't cause any discomfort, since those cells can't feel pain. It's highly unlikely peeps will actively avoid the harmful light unless it's persistently causing discomfort or they're educated to do so and know the type of the light. The funny discoloring/warping spot in vision caused by harmful light alone won't be alerting enough.

The line between safe and unsafe is kind of thin here by the looks of it.

People sometimes like to look into lights in general.

You most likely have had exposed your retinas to lasers more than 0.25s at a time multiple times.

As far as I remember photoreceptor cells on retinas are non-regenerative, so any damage occurred to them is permanent and will be accumulated, and it will only becomes worse overtime. Some damages have delayed effects where your eyesight is okay for hours to days after exposure but then significantly worsens.

Don't accelerate the degradation process for your retina cells for no good reason.

People should avoid looking at lasers in general. Sometimes even the reflection of a laser is unsafe, meaning some shiny objects (sometimes even not shiny ones) can reflect enough of its light to damage your retina cells.

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