Ultra violet light/radiation (UV) is part of the invisible light spectrum that falls between 100 and 380 nanometers (nm). UV light is divided into three ranges, UVA, UVB, and UVC. The range below 280nm is not considered a threat because most of it is filtered out by the earth's protective ozone layer.
Prolonged exposure to high range UVA and UVB radiation can cause eye damage ranging from discomfort to long-term vision problems such as cataracts. While clouds can block much of the visible light, nearly 80% of the invisible UV radiation can still reach your eyes.
Lighter tint lenses do let more "visible" light into the eye; which is harmless. But lighter tinted lenses can still filter out 100% of the "invisible" UV light.
All Optic Nerve lenses (including clear) meet or exceed the U.S. Government and FDA ANSI Z80.3 standards for UV protection. All their lenses filter out 100% of the dangerous UV light up to the maximum 400 nanometers.