How do I determine eye safety limits for IR LEDs?
There are no issues with NIR led power levels like those of remotes.

Laser eye safety standards cover this area. Lasers can have very high pulse power levels at modest average power, and a narrow beam can get the energy through the aperture of the pupil. A narrow source can be focussed onto a narrow spot on the retina, where the flux will be high.

So hazard requires 3 things:


A significant energy must fit through the pupil aperture (7mm) at viewing distances 
The source area must be small enough that it can be focused by the eye to a concentrated spot on the retina. (this is what makes the sun dangerous)
the localised flux in the spot on the retina has to be high enough to cause damage, for NIR/vis that basically means heating


It the past LEDs were not considered able to put hazardous energy levels through the aperture of the pupil, and were not regulated

However there are now very high power leds. The eye protects itself from visible light by closing the iris down, but not from near-IR (or UV), which it can still focus onto the retina as the eye is transparent.

A modern 3W led die can emit 1W of IR from 1mm sq. That is a flux of 1MW/sqm (at the die surface) by comparison sunlight at earths surface is 1.3kW/sqm.

This is not quite as alarming as it might seem, solar flux is reached at 11mm from the die (180deg beam, ~40mm for 30deg beam), and at that distance you cannot focus to the tiny spot on the retina, that you can looking at the sun.

Nevertheless, led flux is now very high, and we gang up lots of leds into massive floodlight, spotlights etc. 

At the other end of the spectrum - Blue, Near UV and UV there is probably more actual hazard. Blue light (and more so UV) is biologically damaging - it breaks down organic bonds. (This is probably why plant use red light, and reflect green light)