What are Category 4 sunglasses and where are they used?
11th Feb 2025
Sunglasses For Sport sell a wide range of Category 4 sunglasses – probably the largest selection available in the UK. But what are they and where are they used?
What are Category 4 sunglasses
The lens category number equates to a percentage of the VLT (Visible Light Transmission) that is, how much light the lens lets through. The higher the VLT the lighter the lens, and conversely the lower the VLT the darker the lens tint will be, blocking more light coming through to the eye. A Category 4 lens lets in between 3-8% of light so it’s a very dark lens that can be in grey or brown tints.
Where are Category 4 sunglasses used
They are ideal for activities like skiing, mountain climbing, high altitude hiking and desert trekking: conditions where high glare or intense sunlight is experienced. Category 4 lenses are also suitable for eyes that are sensitive to bright light, a condition called photophobia. It’s a common symptom that’s associated with several different conditions, ranging from minor irritations to serious medical emergencies.
Can Category 4 sunglasses be used when driving
It's important to know that you must not use Category 4 lenses for driving (they are too dark for driving and could invalidate your car insurance if worn while driving). You will no doubt have seen media scare stories saying you could get fined £5000 for wearing sunglasses whilst driving. These “click bait” stories usually fail to emphasise that the only sunglasses you could get fined for wearing are those with Category 4 lenses.
We’ve made it easy to see all our Category 4 options by putting them into one section.