Infrared. An unseen and unnecessary hazard in ophthalmic devices

The concept of instrument-induced light damage to the retina is well established. Many have argued that ultraviolet (UV) energy is overwhelmingly responsible and that longer wavelength infrared (IR) energy causes thermal change and plays a minimal role. We suggest that infrared may play a primary role in instrument-induced damage. We measured the radiometric and photometric outputs from commonly used ophthalmic devices in normal use and in IR-blocked conditions. We found IR output to represent a significant portion of the total irradiation produced by these instruments. Infrared was easily and inexpensively minimized without compromising usable visible light in these instruments using an efficient IR filter. The instruments' incandescent lamps, glass envelopes, and optics are poor UV emitters or transmitters. Manufacturers' data do not indicate UV emission. Evidence for UV blocking and IR transmission by the intraocular media is presented.