There has long been a debate about the dose response curve, action spectrum and
mechanism for the production of infrared cataracts. Some scientists believe that the
damage mechanism is purely thermal, others suggest that there is some evidence that
it could be photochemical. If the mechanism is photochemical, a strong wavelength
dependence in the near infrared spectral region will be present, and this will have
great significance for lamp safety, IR-A medical devices, occupational exposure limits
and the design of industrial eye protection. With the advent of high-power infrared
LEDs and diode lasers as well as wavelength-tuneable infrared lasers (e.g. Titanium
Sapphire laser), it is now possible for the first time to conduct a definitive and
conclusive laboratory study of the action spectrum for infrared cataract.
Manufacturers of LEDs, lamps and lasers should be intensely interested in the results
of such studies. If the aetiology (cause) is purely thermal, the ambient temperature as
well as the spectral content of the infrared irradiation becomes important and this is
reviewed in this report. Currently the weight of evidence suggests that the aetiological
mechanism is thermal.