When it comes to light transmission, these sunglasses transmit between 80 and 100% of the light. On the other hand, if we’re talking about absorption then these lenses would absorb between 0 and 20% of sunlight. As you can see, these values are inverted.

They react to changes in light conditions, filter out more unwanted, harmful light than other glasses and greatly reduce the strain on eyes – not just on a sunny day but in all weather conditions. And, importantly, outperforming the competition here. Using them really is an eye-opening experience.

The style is deliberately understated. But if you want to jazz them up, there are some pretty vibrant colours for the frames and complimentary mirror-finishes for the lenses – including candy pink or lime green. We also found that because they are quite compact, there was a fair bit of creep around the lower parts of the frame, and with the sun at the side they didn’t prevent reflection of the skin as well as others here. Polarised lenses are usually more pricey, and do help cut down on glare. But they aren't necessary unless you spend a lot of time outdoors in high-glare situations, such as on the water. The Australian/New Zealand Standard for sunglasses and fashion spectacles does not cover either tinted or clear prescription glasses. However, some tinted or clear prescription lenses may provide protection from UV radiation. Certain lens materials and coatings provide UV protection. Lenses that darken when exposed to sunlight provide additional comfort by reducing glare, but do not necessarily filter out more UV radiation. Prescription glasses used for sun protection should be close-fitting and wraparound to provide maximum protection.

Always keep a spare pair of driving sunglasses in the car so they're ready to put on during road trips. Horizontal light occurs when it’s reflected off molecules in the air or when it bounces off large shiny surfaces such as water, snow, buildings or cars. The flat surface re-orientates and condenses the light into what we call glare. Category 3 sunglasses are the most common category and provide added protection from UV light. Our standard dark sunglasses tints are within this category, offering 100% UV protection and filtering out 75% of the light. They come in brown, grey and green. These sunglasses are perfect for everyday wear.

What that means is that when the light levels are more intense, and UV levels are higher, the lenses darken, or lighten in low-lighter areas. This seems like some sort of witchcraft, but Serengeti says it occurs when energy from UV radiation causes the polarity of the silver salt lens molecules to expand in brighter conditions, creating a denser lens that absorbs more light. In darker conditions, the molecules compress and separate to allow in more light. All clear?