When is LED lighting harmful for the eye?

Depending on the illumination level, exposure time, and distance of direct exposure: prolonged, continuous excessive exposure to short-wavelength rich light from indoor (and outdoor) lights, computer monitors, mobile phones and television screens may be enough to damage retinas on the long run. Though, during day time a great amount of blue light is very positive.

What color temperature is more harmful?

Bulbs with a temperature over 5000 Kelvin contain relatively high amount of blue light which can be hazardous to the retina, depending on the illumination level, exposure time, distance and how much blue light you were already exposed to.

What light intenstity is more harmful?

Excessive bright lights can possibly damage the retina, always avoid staring straight into bright lights. Luminance higher than 10,000 cd/m² causes visual discomfort no matter what the position of the lighting source is in the field of vision. Once again, this also depends on the illumination level, exposure time, and distance.

Exposure time to blue light

Excessive exposure to blue light, combined with the illumination level, exposure time, distance, from LEDs in the range 470–480 nm for a short to medium period (days to a few weeks) should be relatively safe, this conclusion cannot be generalized to a long-term exposure (months to years).

Eye strain relieve

E.g. when having direct exposure to bright (LED) light source, like computer screens, give your eyes a break. Use the 20-20-20 rule. Every 20 minutes, take a 20-second break and focus your eyes on something at least 20 feet away.