Are we killing our eyes!!!!

[Shawn O]

I smell a new option that high-end tank builders can offer right here.

I bought a pair of those HD glasses for wearing to the range for target practice but find that they are only usable on overcast days, except for dawn and dusk hours. Just too bright for a sunny day. Would love to get a pair that are clear or smoked. I would imagine they would be less than fun for fish watching as the colors would be altered by wearing them.

Thanks to the OP for this thread, useful info here.

 

[ReefKeeper64]

The tank in my home office has a canopy but I sit at eye level and can see some of the lighting in my peripheral vision. I'm seeing the tank out of the corner of my eye all day long so I wonder if this is a long term risk? I also wonder if tanks can be built with UV protection already in the glass panels? Any thoughts out there on this?

 

[davocean]

Just do a goggle search. There is already TONS of research showing the damaging effects of blue light. You could also ask your Optometrist at your next eye exam. As for the other things, I don't really worry much about any of them. Some of them are beyond my control, others are mostly harmless and may happen from time to time, but I worry about my eyes. They are irreplaceable and if I can do something simple to protect them, I will.

I will ask my optometrist, but he does happen to have a cool 240g in the waiting room as well as one at home!

But I do hear how that can have an affect w/ enough time and actually have some clients looking at certain light spectrums and health issues, but in all honesty I'm pretty sure my PC screen does more harm than anything.

 

[Jyetman]

When you wear these blue blockers can you still see blue light while looking at the tank?

 

[gprdypoo04]

I'd be more concerned about the North Korea nuke lighting things up.

 

[alton]

The only benefit of wearing prescription glasses is the fact that I have always added UV protection to my list of options. Does it really help that much? Yes it does. My wife last year had cataracts and had to replace her lenses on her eyes. With the new $13,000 surgery/lenses she no longer has to wear glasses to read/drive like she did before the surgery. Except when she goes out in direct sunlight now she always wears sunglasses, where as before she didn't even own a pair.

 

[Kevin Guthrie]

According to this if you want to avoid macular degeneration then don't work outside, don't smoke, don't be a guy, and do eat lots of fruit.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3342546/table/T2/

 

[Tripod1404]

I doubt it would be stronger than the light that would hot you eye on a sunny day. Even if you dont directly look at the sun, light reflected is still pretty strong.

During the last solar eclipse we had 97% blockage where I lived. I used a PAR meter to measure the light intensity outside. It was 177 W/m2... That is more than what the bottom sides of my tank gets, with freaking 97% blockage.

So light reflected from your neighbors car while you are looking outside is probably much stronger than artificial lights.

 

[der_wille_zur_macht]

Can anyone quantify the statements being made here?

How much light in what wavelength over what exposure time produces what sort of result?

How much light in that spectrum do our tanks produce?

Otherwise this all sounds like acting afraid of drinking a glass of water because you can drown in the ocean.

 

[Jyetman]

I'd be more concerned about the North Korea nuke lighting things up.

Agree, they need to be sneaky send that freaky kim twit a good USA gesture trucks loaded with oozing artery blocking big macs and fries that should temporarily curve his hunger for power and hopefully put him on life support lots of tubes up his nose and his ahhh yeah!

 

[mikluha]

Here are some numbers. Numbers are based on assumption, therefore, please read assumptions.



Assumptions:

1. LED is a point source (i.e. its dimensions are negligible comparing to distance)
2. LED is at the height H=14"=355 mm above water level at the center of a fishtank. Tank width W=24"=610 mm
3. Eye pupil diameter D= 7 mm (fully dilated pupil - what's required by laser safety standard). This correspond to unrealistic case when you sit in completely dark room and LED is turned on all the sudden. Makes sense for lasers, but not much sense in our case. In reality, pupil diameter, when looking at the tank would be 4-5 mm
4. Distance between eye and LED
5. LED is a Lambertian source. Of course, most LED has front lens or other type of light concentrators. It results in more "useful" light for the tank and less leakage into the eye. So, Lambertian would be the worst case.
6. Will use radiometric quantities as opposed to photometric, since energy is what matters
7. Eye is right next to fishtank front glass, at its top.
8. Eye is turned up, so it looks right at the LED. It makes thing worse (more energy). We can omit cosine
9. LED electrical power P = 1W in blue part of spectrum. Results should be multiplied for real LED values
10. Blue LED efficiency b=24%, i.e. for each 1W of electrical power, the blue LED produces 0.24W of light energy. Neglecting losses in power supply (based on Luminus PT-40)
11. Radiation is not focused at the eye retina, i.e. this is not a laser source

Calculations:

• Angle between LED normal (vertical) and viewing direction: a=atan(W/(2H))=atan(305/355)=0.71 rad = 41 degrees.
• Distance between LED and the eye L=sqrt(H^2+(W/2)^2)=468 mm = 18.5"
• Pupil area: S=pi*D^2/4=39 mm2
• Solid angle subtended by the eye from LED: dA=S/L^2=1.75 E-4 steradian = (approximately) 0.0002 sr
• LED radiant flux: F=b*P=0.24W
• LED is lamebrtian, so its maximal radiant intensity (similar to photometric luminous intensity) is at normal direction: Imax=F/pi=0.24/3.14=0.076 W/sr
• Radiant intensity into direction at eye : I=Imax*cos(a)=0.076*cos(40)=0.058 W/sr
• Radiant flux into eye: dF=dA*I=0.058*1.75e-4=1.0e-5 W=10 uW (microwatt)

So, per each "blue" LED watt human eye receives 10 uW into pupil.

Estimating MPE (maximum permissible exposure - IEC-60825-1 standard, is a incredible mess, so we use guide: http://onlinelibrary.wiley.com/doi/10.1002/9781118688977.app1/pdf, Table A4,
wavelength 0.4-0.5 um, exposure time = 3000 s, Photochemical damage to retina, retinal burn ): MPE=1.e-4 W/cm2 (power density).

Power density (W/cm2): U=dF/S (S - in cm2 now) = 1.e-5/0.39=2.64e-5 W/cm2)

So, we're U/MPE=0.26, i.e. you can safely stare into 4W blue LED for 1 hr

For occidental short exposures (10s), MPE=1.8e-3*t^0.75 (J/cm2)= approximately 1e-2 J/cm2.
Our case Q=U*t=2.64e-5*10=2.64e-4 J/cm2

So, Q/MPE=2.64e-4/1.e-2=0.026, so you can safely stare into 40W blue LED for 10s

Again, each case is different, the model is very simplified, however, it should give you some idea.