Visible Light Transmission (VLT) refers to the amount of visible light that passes through the lenses of laser safety glasses. This value affects how bright or dark the eyewear appears during use.

Higher VLT percentages allow more visible light through the lens, resulting in brighter viewing conditions. Lower VLT values create darker lenses that reduce brightness.

Balancing VLT with laser attenuation is an important consideration when selecting protective eyewear. In many professional environments, users require strong laser protection while still maintaining practical visibility for equipment operation or procedural work.

Different filter colours and wavelength requirements can influence VLT levels. Some high optical density filters naturally reduce visible light transmission more than others.

Understanding VLT helps users select eyewear that balances protection with usability.