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Glossary
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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Anti-Reflection Coat
A special coating on the surfaces of a lenses which reduces unwanted reflections. This improves cosmetic appearance, reduces glare and improves contrast.
Note: Anti-reflection coatings make lenses look much clearer, so any grease and dirt on the lens surface is more visible. Cleaning the lenses with a microfibre cloth rapidly restores them to optimal condition. A special easy-clean anti-reflection coating is also available which is easier to keep clean.
Aspheric
A special, high performance lens design which reduces visual distortion. As well as providing better vision, aspheric lenses also appear thinner than standard lenses. Highly recommended for spectacle wearers with high prescriptions. See also: Thinner/flatter lens.
Bifocal Lens
A segmented lens that provides the function of both reading and distance spectacles in a single lens. The reading portion is positioned in the lower part of the lens. Various sizes of reading segment are available; D25, D28, R25: the letter refers to the shape of the segment. 'R' indicates a rounded segment, whereas 'D' indicates a flat-top segment, like the letter D lying on its side. The number indicates the segment size in millimetres. See also: Distance Spectacles, Reading spectacles, Varifocal Spectacles.
Bridge
The part of the spectacle frame which fits over the nose and holds the rims of the glasses or lenses together.
Clean 'n' Clear
A special Kodak® anti-reflection / anti-scratch coating with a super-smooth water-repellant and dirt-repellant surface.
Dioptre
A measurement of the power of a lens. (specifically, the reciprocal of the focal length of the lens in metres)
Distance glasses
Glasses with single vision lenses, that correct the wearer's distance vision. Young people and people with good focusing power, can also read with distance spectacles.
Anti-Reflection/Anti-Scratch Coating
A combined anti-reflection and anti-scratch coating with a special easy-to-clean coating which resists dirt and dust build-up.
Flexi-Joint frame (Also called Flex joint)
A frames fitted with sprung hinges, providing greater comfort and resistance to breakage.
Flexi Frames
Frames made from a material called 'memory metal' which returns to its original shape after being bent. Provides greatly improved resistance to breakage.
Glazing
The process of shaping a lens to the correct size and fitting it to a frame.
Graduated tint
A tint which is darker at the top of the lens, fading to a lighter shade at the bottom. See also: Tinted lens, Solid tint.
Hydrophobic
A special lens coating which repels water, causing it to bead into droplets and run off.
ImpactX
A revolutionary range of lenses from Rudy Project, incorporating NXT - a very resilient lens material, guaranteed unbreakable for life.
Intermediate vision
The focal range between the far distance and typical reading distances. This is typically the distance at which a computer screen or television is viewed, or manual work is performed.
Iridium®
A special type of sun lens from Oakley with a reflective surface finish.
Laser (MultiLaser)
A special type of sun lens from Rudy Project with a reflective surface finish. MultiLaser lenses are reflective and iridescent.
NXT®
A revolutionary, semi-rigid lens material used in Rudy Project ImpactX lenses. Combines outstanding optical performance with unparalleled durability. Guaranteed unbreakable for life.
Photochromic lens
Lenses which darken when exposed to bright sunlight, fading back to a very slight tint when indoors. Photochromic lenses also block UV light, helping to protect your eyes from potentially harmful effects.
Polarised lens
A special type of tinted lens which dramatically reduces glare due to reflected sunlight, as well as improving contrast. Particularly recommended for daytime driving and outdoor sports such as angling, golf and sailing.
Prescription
A medical document provided by your optometrist, describing the lens powers required to correct your vision.
Pupillary Distance (PD)
This is the distance from the centre of one pupil to the centre of the pupil in the other eye, expressed in millimeters. Often given the abbreviation PD or referred to as the centration distance. This measurement does not normally form part of your eye examination, although your optician may supply it for a fee. We offer a free, on-line PD measurement service.
Reading spectacles
Spectacles fitted with single vision lenses for viewing at close distances, for reading, close work or sometimes VDU (desktop computer) work.
Rimless frame
Spectacles which do not have a supporting rim around the lenses. These frames are usually lighter and therefore more comfortable to wear than standard frames. See also: Supra Frame
Sides
The side of the frame. Sometimes referred to as the arms.
Side length
The distance from the joint of the spectacle frame to the point at which the side bends behind the ear.
Solid tint
A tinted lens which is the same density and colour over the whole lens area. See also: Graduated Tint
Standard lenses
Plastic lenses made from a clear acrylic material called CR39. See also: Thinner/flatter Lens, Anti-reflection Coat, Hard Coat
Supra frame
A frame which does not have a lower rim; sometimes referred to as a semi-rimless frame. Often the lens is fixed by means of a nylon cord running through a groove cut into the edge of the lens. These frames are usually lighter and therefore more comfortable to wear than standard frames. See also: Rimless frame
Thinner/flatter lens
A high-performance lens made from a different type of material, compared to standard lenses. These lenses may also be of an aspheric design. Both features result in significantly thinner lens. With higher-powered lenses, thinner lenses give a much better cosmetic appearance. Note: Choosing a frame with smaller rims will also make your lenses appear thinner.
Tinted lens
This is a lens which has been treated with a coloured or neutral-grey dye. In general, only uncoated plastics lenses may be tinted with this process. See also: Solid tint, Graduated tint
UV light
UV, or Ultra Violet light is a normal component of sunlight and some other light source, which produces a sun tan, and causes sunburn. Prolonged exposure to UV light can damage your eye and cause conditions such as cataract. You can protect your eyes by choosing a lens which blocks UV.
ALL OF OUR SUNGLASSES, POLARISED AND PHOTOCHROMIC LENSES INCLUDE UV BLOCKING AS STANDARD
UVSun
A range of high-performance Kodak® Polarised lenses. UVSun lenses cut out up to 99% of reflected glare and are the ideal sun lens.
Varifocal lens
A specially designed lens that provides the function of both reading and distance spectacles in a single lens, but without the noticable segment line found in bifocal lenses. The upper area of the lens corrects distance vision, whilst the lower-central area provides the correct power for reading and close work.
See also: Bifocal lens, Distance Spectacles, Reading Spectacles
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