If you are curious, the smallest doses where "blue light hazard" has been observed in humans (short-term exposure) are around 10 J/cm^2. International standards use around 2 J/cm^2 for a safety margin.

One example of this is hiking in fresh snow for hours, no sunglasses, meaning exposures well above 10,000 cd/m2 to "white light".

Computer screens are way dimmer - an hour of iPad use is .0365 J/cm^2.

http://www.nature.com/eye/journal/v30/n2/full/eye2015261a.ht... is a good summary.

For long-term exposure (AMD risk) we have very little data, so understanding the mechanisms (such as above article does) can help.