What luminous intensity of LED lights can damage retina human eye?

The luminous intensity of LED (Light Emitting Diode) lights that can damage the retina of the human eye depends on several factors, including the wavelength of the light, the duration of exposure, and the individual's susceptibility. However, according to the American National Standards Institute (ANSI), the maximum permissible exposure (MPE) for the retina of the human eye is set at 10 mW/cm² for visible light between 400 and 700 nm. Exceeding this MPE level for an extended period can lead to retinal damage, including photochemical injury and thermal damage.

It's important to note that the luminous intensity of LED lights is measured in lumens, which is a measure of the total amount of light emitted by a light source in all directions. However, the damage to the retina is caused by the radiant intensity, which is the measure of light power emitted in a specific direction. Therefore, even if an LED light emits a high total luminous intensity, it may not necessarily pose a risk to the retina if the radiant intensity in the direction of the eye is below the MPE limit.

To ensure eye safety, it's recommended to adhere to the recommended guidelines and standards set by organizations such as ANSI and the International Commission on Illumination (CIE) when using LED lights. Additionally, it's essential to avoid direct eye exposure to high-intensity LED light sources, especially those designed for specialized applications like spotlights, stage lights, or medical devices, as they may exceed the MPE levels.