If you wear glasses then you will know how helpful it is to have prescription sunglasses for those long sunny summer days or when the winter sun is low and bright. Even if you wear contact lenses it is advisable to have a pair for occasions when your eyes feel dry or you want that added convenience.
Just as UV can damage your skin this radiation can damage your eyes, both the exterior layer as well as the internal lens causing premature cataract and the retina increasing the risk of macular degeneration. When you wear a tinted or dark lens the pupil will dilate (as it does in darkness to improve vision) and therefore it is vital that the sunglass lens filters out UV light.
The International Standard is elimination of UV light up to 400nm just below the visible spectrum. It is important that your sunglasses protect fully from UV and have a CE or other regulatory mark to confirm quality and compliance. All our prescription and non prescription sunglasses have full UV protection and conform to all International Standards.
A standard sunglass lens with CE or other mark will provide UV protection whether the tint is light or dark. Please note that a lighter tint will not provide as much comfort (or perceived protection) as a darker tint.. If you are very sensitive to sunlight then you should choose a darker lens tint.
There are a number of different categorisation systems used by sunglass manufactures with the most popular being that used by Luxottica, manufacturer of sunglass brands such as Ray Ban and Oakley. They use a number system from category (or grade) 1 to 4, with 1 being the lightest tint and 4 darkest. You may find a note of this on the packaging eg most Ray Ban sunglasses have a category 3N lens meaning that the tint is a category 3 and the lens type is a neutral N sunglass.
If you purchase a polarised sunglass then the mark will contain a ‘P’ therefore 3P.
It is very rare to find grade 1 sunglass lenses whilst grade is an obvious light tint more desirable for it’s fashionable look. The darkest sunglass lenses will be at grade 4. Please note that you should not drive wearing grade 4 dark sunglass lenses as your vision may be reduced and driving unsafe.
At Pretavoir we manufacture all our lenses to grade 3 as standard, the most popular lens tint suitable to provide you with comfortable vision in the sun and safe for driving.
Sunglasses Lens Grading
80 - 100%
45 - 80%
20 - 45%
3 - 8%
Very Pale Tint often indistinguishable from clear.
Pale Fashion Tint. Not suitable for night driving.
Medium Tint. Not suitable for night driving.
Dark Tint. Not suitable for night driving.
Very dark Tint. Not suitable for daytime driving.
Sunglasses Lens Colours
Provides warmer, brighter colour perception that Grey or Green tint.
Provides a more neutral slightly cooler colour perception that Grey or Green tint.
Provides a more neutral sensation and colour perception. (Also known as G15).
These lenses provide full UV protection as all other lenses however have the added function of cutting out reflected light.
When light falls onto a flat or especially as shiny or smooth surface then the reflected light becomes more intense and polarised. The answer to this harsh glare is the polarised lens. When worn you experience a much more relaxed and clear vision devoid of distracting glare and reflections.
These lenses are available in three main colours; brown, grey and green. If you wish to achieve the ultimate sunglass lens combination then a back surface anti reflection coating will allow you the very best sun vision.
This type of sunglass has a dark tint at top portion of lens, smoothly reducing to a light tint at bottom portion.
This lens type is popular with drivers as light from road ahead is blocked whilst the dashboard is less affected. For the same reason those wishing to read with their sunglasses may find gradient lenses beneficial. However the reason why most gradient lenses are fitted is due to their elegant, fashionable appearance.
This coating is applied to the front surface of a tinted lens and has the effect of increasing light absorption whilst providing a striking reflective one way mirror look. This lens is also known as a flash mirror and is popular in brands such as Ray Ban and Oakley.
At Pretavoir, we are able to provide prescription lenses with this coating whether the base lens has a standard tint or polarised.
Light scatters in all directions, however when reflected from flat surfaces such as water or a shiny surfaces the reflected light is much more intense. On these occasions polarised sunglasses block out these intense rays resulting in calm and comfortable vision.
UV Protection and Clear Optical Lenses
Standard Glasses do not provide protection from UV light. However, higher index (thinner) lenses do cut our UV light up to 395nm. Therefore it may be beneficial to choose 1.6 index for your glass both to reduce edge thickness as well as help protect against UV.
Please note that all Zeiss lenses from standard index 1.5 provide full UV protection through their DuraVision UV coating which is provided with all Zeiss lenses purchased from Pretavoir.
Transitions and PhotoFusion
Transitions and PhotoFusion lens materials provide a solution in both sunlight and indoors light conditions.
These special lens materials react to the UV light falling on their surface changing their molecular orientation to transform quickly from a clear lens to tint and reduce glare. In the reverse direction once you move from sunlight to a darker indoor situation the the lens will return to its clear light state. Please note that these lenses provide full UV protection in fully clear status.