Sunglass Lens Information
Information Regarding Prescription Sunglass Lenses
Many assume that because they require a prescription lens that this excludes them from the full range of sunglass lenses on offer. This is not the case at Spex4Less.
Here, we can produce a wide variety of exotic lenses made to your prescription such as Polarised, Photochromic, Wrapped and even Mirrored sunglass lenses are available.
All prescription sunglasses supplied by Spex4Less block 100% UVA & UVB rays regardless of whether or not you select the free UV coating option when customising your lenses.
Below you will find further information on the types of sunglass lenses, colours and coatings that we offer.
Sunglass Lens Categories, LTF & Absorption Levels (Darkness).
When you order a pair of prescription sunglasses from Spex4Less, we will manufacture them to a Category 3 level as standard. This is a typical sunglass level suitable to protect your eyes from bright sunlight whilst also being suitable for daytime driving. Here is a description for each sunglasses category along with their respective LTF (light transmission factor) and light absorption levels. Please note if you require Category 0,1,2 or 4 lenses, you will need to place a special order via our helpline.
(LTF 80% - 100%)
(Absorption 0% - 20%)
Very pale to clear lenses for overcast and indoor use. Suitable for driving in the day time and at night.
(LTF 43% - 80%)
(Absorption 20% - 57%)
A pale tint for low light and fashion use. Not suitable for driving at night time.
(LTF 18% - 43%)
(Absorption 57% - 82%)
Medium tint for medium conditions. Not suitable for night time driving.
(LTF 8% - 18% LTF)
(Absorption 82% - 92%)
A dark tint for bright conditions. Not suitable for night time driving.
(LTF 3% - 8% LTF)
(Absorption 92% - 97%)
Very dark lenses for very bright conditions. Not suitable for driving at any time.
* Category 3 is the standard prescription sunglass level used when ordering prescription sunglasses at Spex4Less. When producing your lenses we aim to achieve 15% LTF (85% Absorption). For any other Category or LTF value please call for a quote on 0151 632 6611.
Sunglass Lens Colours
A standard Brown sunglass lens offers warmer, brighter colour perception than the Grey or G15 lens.
Standard Grey sunglasses offer a more neutral, slightly cooler colour perception than Brown lens.
A dark green/grey lens again offering more neutral and cooler colour perception than a Brown lens.
Mirrored sunglass lenses are also available made to your prescription. They can help to reduce glare but the main benefit is the lens aesthetics.
Currently, we offer Grey with Silver Mirror, Brown with Gold Mirror, Grey with Blue Mirror and Grey with Fire Red Mirror.
Polarised lenses are available in Grey and Brown and at first, glance appears to be regular Grey or Brown sunglass lenses. However, they also contain a polarising filter.
Light which is reflected from a flat surface such as a wet road or water becomes horizontally polarised. This horizontally polarised light is blocked by the polarising filter in the lens which dramatically reduces the glare from these reflections.
Polarised lenses are ideal for Fishing, Sailing, Golf and general use. However, those that also need to use LCD screens whilst wearing their sunglasses will find polarised lenses more of a hindrance. This is because screens of this nature emit polarised light which is blocked by the filter in the lenses making the screen difficult if not impossible to view through polarised lenses.
In the presence of UV a chemical reaction occurs inside a Photochromic lens which turns the lens darker. We offer standard Grey and Brown Photochromic lenses. They are clear indoors but outside in the presence of UV they turn into a darker sunglass lens. This offers you the correct amount of protection for the various light conditions, the more UV they receive the darker they go.
Unfortunately, because Photochromic lenses require UV to react, they do not work well when used behind a car windscreen. This is because most windscreens today have a UV filter inside them which prevents the UV from reaching your lenses.
However, Transitions have created a lens called Transitions Xtractive. These are almost completely clear indoors (a very pale tint) but react to approximately 50% behind a car windscreen. Outdoors, in the presence of UV, they react to a full dark sunglass tint.
Drivewear lenses combine both Photochromic and Polarising lens technology. Indoors and in low light conditions they remain yellow colour, in medium light and, behind a car windscreen, they react to a copper colour. Outdoors in bright sunlight the reaction continues and the lenses turn to a dark brown colour. Drivewear lenses also contain a polarised filter to reduce reflections just as a standard polarised lens does.
Our in-house glazing laboratory is able to glaze high base prescription lenses & wraparound frames. This means that wraparound sunglasses are now available to those who require prescription lenses. Wraparound frames are only suitable for prescriptions which are within the combined sph and cyl power range: -4.00 to +6.00. We will let you know if the combined prescription you have entered falls outside of the acceptable range.
Choose your new prescription sunglasses today!