Is infrared bad for eye's retina?

That's a good question. Infrared light is not different than any other photon, except its energy is lower than visible light. However, photon energy alone is not sufficient to insure NO DETRIMENTAL effect occurs. If the amount of energy absorbed (here in your tissues of the eye) is above some threshold, damages occur. So you want to adjust the flux of infrared light to be much below that threshold. The key figure is "power density", but I do not know the  number. People doing surgery use sometimes infrared sources, so the literature there has what you need.

All infrared, visible or ultraviolet electromagnetic radiation can cause injury to the eye in sufficient concentrations, but this is very rare.T he infrared light needs to be extremely intense to cause harm.  In extreme cases, if the eyes absorb too much infrared light, they can be irreversibly damaged.

Comparing the energy from iPhone LED screen, is the light energy from LED screen much higher than Infrared light's energy?  If yes, we can ignore this issue.

Does anyone have any suggestions?
Thanks, to everyone very much for any suggestions (^v^)

Post Merge: 5 years ago

Referring to following statement, I would like to know on how infrared radiation effects protein within the lens of the eye.

Does anyone have any suggestions?
Thanks, to everyone very much for any suggestions (^v^)

"studies have found that the protein found in the lens of the eye is very sensitive to the infrared radiation used in the biometric and when exposed, can lead to cataract."

https://www.dailymail.co.uk/sciencetech/article-4597594/Samsung-users-say-iris-scanner-causing-eye-discomfort.html

An iPhone's screen uses LED lighting in its display. The LED light is within the visible spectrum (see link for reference)

https://biology-forums.com/index.php?action=gallery;sa=view;id=30288

Infrared is also emitted by the screen, but because its wavelength is outside the visible spectrum, so it's invisible.

Wavelength and energy are related by a combination of two formulas. \(E = hν\), where E is the energy in Joules, h is Planck's constant (\(h=6.626\cdot 10^{-34}\)), and ν is the frequency of the light in units of \(s^{-1}\) (or Hertz, Hz). Frequency is related to wavelength by \(λ=\frac{c}{v}\) , where c, the speed of light, is \(3.0\cdot 10^8\ \frac{m}{s}\). Combining these two formulas and you get: \(E=\frac{hc}{\lambda }\) which you can use to calculate energy.

The effects of infrared and visible light would have a similar effect on the eye.