With the Summer in full swing, the blinding glare caused by a low sun, or by bright light can often be potentially dangerous, especially when driving at speed on a long motorway journey or on country roads.
Glare is frequently cited as the cause of road traffic accidents, but the right pair of sunglasses can prevent it. Whilst there is some confusion about what sort of sunglasses you should wear when driving, at Blink Opticians we have an easy to understand guide to what sort of eye wear you should be wearing.
Clarity of vision
There are two essential requirements for lenses to be used for driving – your vision must remain clear and the glasses must allow sufficient light to get to your eyes. Sunglasses sold for general use can be too dark or unsuitable for driving so make sure they’re not too dark and where possible use a pair with a ‘fixed’ or ‘variable’ tint.
Fixed tint lenses
These remain the same darkness regardless of light conditions. Fixed tint sunglasses are readily available at Blink Opticians and a fixed tint can be added to prescription, or corrective, glasses as well . Polarised lenses normally have a fixed tint, but their inherent properties can significantly help to reduce glare. Their effect can be very evident on wet roads.
Variable tint lenses
Generally known as ‘photochromic’ lenses, these have the advantage of changing their colour density when exposed to varying UV lights. When the UV source fades, the lenses revert to their previously clear state. For variable tinted glasses we use Transitions XTRActive lenses as they darken behind the windshield of your car, even though it mat be tinted or contain a UV filter.
- Tinted lenses are graded according to the density of the tint, and all sunglasses should, by law, be labelled and show the filter category number.
- Lenses with light transmission less than 75% are unsuitable for night driving.
- Yellow tinted lenses are not recommended for night driving. The tint is likely to be unperceivable anyway if the lens has a light transmission factor of 75% or more to meet night driving requirements.
- Lenses with light transmission less than 8% are unsuitable for day or night driving.
- Due to the light levels within the car, filter category 2 lenses which transmit between 18% and 43% of light are recommended for daytime driving.
- Filter category 4 lenses only transmit between 3% and 8% of light and are not suitable for driving at any time. Sunglasses with these lenses should, by law, be labelled ‘Not suitable for driving and road use’.
Other things to consider
- All sunglasses should carry the CE mark and meet the European Standard BS EN 1836:2005.
- A good quality anti-reflection coating is recommended, along with a hard coating to protect the lenses from scratches.
- Sunglasses with deep side arms can block side, or peripheral, vision and are not recommended for driving.
- Ensure that all sunglasses are removed when the street lights come on. No matter how cool they look, sunglasses should never be worn at night time when it is dark.