Visible Light Transmission (VLT) describes the percentage of visible light that passes through a laser safety lens. It influences how bright or dark the surrounding environment appears while wearing the eyewear.

Higher VLT values provide a brighter viewing experience, while lower values result in darker lenses.

The amount of visible light transmitted depends on the filter technology required for the intended laser wavelength. Some filters achieve high protection while maintaining relatively high visibility, whereas others require darker lenses to provide the necessary attenuation.

VLT should not be confused with Optical Density, which measures laser attenuation rather than brightness.

Understanding VLT helps users compare different laser safety glasses and select eyewear that balances protection with workplace visibility.