Types of Spectacle Lenses and Coatings
Which glasses lenses are best for me?
Everyone's eyes are differerent. The lenses that best suit you depend on the strength of your glasses prescription, the type of glasses you choose and the activities you use your glasses for.
The simplest form of spectacle or contact lens is the single-vision lens, made to a single prescription to correct a particular eyesight problem. Concave lenses are used to correct short sight and convex lenses to correct long sight. Concave lenses are generally thinner in the centre than they are at the edge and convex lenses are usually thinner at the edge than at the centre. The curvature of the lens, its thickness and weight will depend on the amount of long or short sight it is designed to correct. The lens material will also influence the thickness and weight of your lenses, as will the size and shape of the spectacle frame you choose. Traditionally, spectacle lenses were made of glass but most lenses are now lightweight plastic and there is a wide range of materials available to suit your prescription and lifestyle.
Bifocal lenses contain two optical corrections with a distinct dividing line between the two parts. The most common use of bifocals is for people who have become presbyopic and need a different prescription for close work. The upper part of the lens corrects distance vision and the lower half is for near vision. Trifocals are also available that have three sections and incorporate a correction for intermediate vision. Bifocals and trifocals come in a range of designs but nowadays varifocal lenses are much more likely to be prescribed.
Varifocal or progressive lenses
Varifocal lenses, also known as progressive lenses, are used for correcting presbyopia but unlike bifocal lenses have no visible dividing lines between the different corrections. Instead they have a graduated section in which the power of the lens progresses smoothly from one prescription to the other, allowing the wearer to see clearly at all distances. These lenses also have the benefit of looking better - they don't draw attention to the ageing process. A range of varifocal designs is available depending on your lifestyle and occupation. Modern lens technology means that there are many different designs and materials to choose from. We can advise you on the best lenses to suit your individual requirements.
High-index and aspheric lenses
If you need high-powered lenses you can improve the weight or appearance of your glasses with special lens materials and designs. Opticians will often refer to this as "thinning" of the lenses but it actually means that we are using a different lens material that gives a thinner result. These
High-index materials and aspheric designs mean that lenses can now be made thinner, lighter and better looking than traditional lens types. High-index materials make lenses for short sight thinner, while aspheric designs that minimise the amount of material make lenses for long sight both thinner and lighter.
Whatever your prescription, it is important to protect the eyes against excessive ultraviolet (UV) radiation. Protection is needed to avoid reflected light from sand and snow or if you spend long periods out of doors, particularly in the summer. Prescription sunglasses can be made with single-vision, bifocal or varifocal designs to offer the same standard of protection as non-prescription sunglasses.
Safety and sports glasses
Special lenses and frames incorporating eye protection are available for a variety of safety and recreational uses.
Spectacle lenses can be provided with anti-reflection coatings which virtually eliminate distracting reflections off the lens surfaces. Reducing reflected light is particularly helpful for computer users and for night driving. Anti-reflection coatings also improve the cosmetic appearance of your glasses and can make thick lenses look thinner.
Scratch-resistant / hard coating
Plastic lenses are lighter than traditional glass lenses but they scratch more easily. Scratched lenses can be irritating for the wearer and look unsightly. Scratch-resistant coatings are available to protect against damage and prolong lens life.
Multi-coated lenses corporate a combination of coatings - anti-reflection, scratch-resistant, water repellent and UV - to combine to improve the properties of your spectacles.
Blue Filter Lenses
Blue filter lenses filter out blue light from artificial light like VDU computer monitors and are designed to reduce eye fatigue. Our blue filter lenses are combined with a scratch resistant coating to make you lenses last longer.
Photochromic lenses react to light so that indoors or in dull conditions they have a light tint, and in bright light they darken to eliminate glare and protect the eyes against UV. Modern photochromic materials react and fade quickly, suit most prescriptions and are more likely to be lightweight plastic than glass.
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