Welcome to our Lens page, there are many different types of lenses that we have on offer but they must suit your needs and lifestyle. Choosing the correct lenses will often determine how happy you are with your eyewear.
When buying glasses the frames are important to your style, appearance and comfort but the lenses will give you confidence, control and the correct vision needed to complete the simplest to the most complex tasks.
A common mistake when choosing lenses is not considering the choice of lens thickness (index) and coatings available. This applies to Single Visions, Bi-focals and Varifocals, the descriptions below will hopefully allow you to understand what is available and how important they can be to you.
In the early days of vision correction, all lenses were made of glass.
Although glass lenses offer exceptional optics, they are heavy and can break easily, potentially causing serious harm to the eye or even loss of an eye. For these reasons, glass lenses are no longer widely used for eyeglasses.
Please note we can supply glass lenses if required but our personal and professional choice is always plastic.
In 1947, the Armorlite Lens Company in California introduced the first lightweight plastic eyeglass lenses. The lenses were made of a plastic polymer called CR-39, an abbreviation for “Columbia Resin 39,” because it was the 39th formulation of a thermal-cured plastic developed by PPG Industries in the early 1940s.
Because of its light weight (about half the weight of glass), low cost and excellent optical qualities, CR-39 plastic remains a popular material for eyeglass lenses even today.
In the early 1970s, Gentex Corporation introduced the first polycarbonate lenses for safety glasses. Later that decade and in the 1980s, polycarbonate lenses became increasing popular and remain so today.
Originally developed for helmet visors for the Air Force, for “bulletproof glass” for banks and other safety applications, polycarbonate is lighter and significantly more impact-resistant than CR-39 plastic, making it a preferred material for children’s eyewear, safety glasses and sports eyewear.
A newer lightweight eyeglass lens material with better impact-resistant than polycarbonate is called Trivex (PPG Industries), which was introduced for eyewear in 2001.
Lens materials and their Refractive Index’s –
The higher the refractive index of a material, the slower light moves through it, which results in greater bending (refracting) of the light rays. So the higher the refractive index of a lens material, the less lens material is required to bend light to the same degree as a lens with a lower refractive index.
In other words, for a given eyeglass lens power, a lens made of a material with a high refractive index will be thinner than a lens made of a material with a lower refractive index.
The refractive index of current eyeglass lens materials ranges from 1.498 (CR-39 plastic) to 1.74 (a specific variety of high-index plastic). So for the same prescription power and lens design, a lens made of CR-39 plastic will be the thickest lens available, and a 1.74 high-index plastic lens will be the thinnest.
Abbe Value. The Abbe value (or Abbe number) of a lens material is an objective measure of how widely the lens disperses different wavelengths of light as light passes through it. Lens materials with a low Abbe value have high dispersion, which can cause noticeable chromatic aberration — an optical error visible as coloured halos around objects, especially lights.
All lightweight eyeglass lens materials (see table) have surfaces that are significantly softer and more prone to scratches and abrasions than glass lenses. The softest eyeglass lens is also the one that is the most impact-resistant: polycarbonate. But all plastic and high-index plastic lenses require a factory-applied anti-scratch coating for adequate lens durability.
Most of today’s modern anti-scratch coatings (also called scratch coats or hard coats) can make your eyeglass lenses nearly as scratch-resistant as glass.
An anti-reflective (AR) coating makes all eyeglass lenses better. AR coatings eliminate reflections in lenses that reduce contrast and clarity, especially at night. They also make your lenses nearly invisible, so you can make better eye contact and you and others aren’t distracted by reflections in your lenses. AR-coated lenses are also much less likely to have glare spots in photographs.
Anti-reflective coating is especially important if you choose high-index lenses, because the higher the refractive index of a lens material, the more light the lenses reflect. In fact, high-index lenses can reflect up to 50 percent more light than CR-39 lenses, causing significantly more glare, unless AR coating is applied.
Cumulative exposure to the sun’s harmful ultraviolet (UV) radiation over a person’s lifetime has been associated with age-related eye problems including cataracts and macular degeneration.
For this reason, people should protect their eyes from UV beginning in early childhood. Thankfully, polycarbonate and nearly all high-index plastic lenses have 100 percent UV protection built-in, due to absorptive characteristics of the lens material.
But if you choose CR-39 plastic lenses, be aware that these lenses need an added coating applied to provide equal UV protection afforded by other lens materials.
Photochromic treatment (Transitions)
This lens treatment enables eyeglass lenses to darken automatically in response to the sun’s UV and high-energy visible (HEV) light rays, and then quickly return to clear (or nearly clear) when indoors. Photochromic lenses are available in virtually all lens materials and designs.
Polarized lenses reduce glare reflected off surfaces, making images appear sharper and clearer. They are available for non-prescription and prescription sunglasses, and can be worn indoors by light-sensitive people, including post-cataract surgery patients and those continually exposed to bright sunlight through windows. Most polarized lenses provide UV protection, which is important to maintaining healthy eye sight.
Blue V is a next-generation lens coating that combats digital eye strain by reducing your exposure to blue light from smartphones, tablets, computer screens, televisions, energy-efficient lighting, and the sun. This attractive, near-clear coating also optimizes visual performance, improves visual comfort, enhances your appearance, and extends the life of your lenses.
We can add a tint to any lense, all tinting is done in house and we can show you a range of colours to choose from.
Types Of Lenses
Single Vision lenses are the optical industry’s standard for the majority of prescriptions. It is the most basic type of lens for glasses where the whole lens is made to the same prescription. We can produce these in a ‘Reading, ‘Intermediate’ or ‘Distance’ prescriptions.
Bifocal lenses consists of two parts. An upper section for clear long distance vision (walking, driving, TV etc), and a lower segment (usually in a half-moon shape – D28, D35) which is stronger and allows the eye to focus closer up. These lenses give nice wide viewing areas for both long-distance and close-up, but it might not be easy to focus on middle-distance items, for example computer screens and music stands.
Varifocal (Progressive) lenses work by having a gradual change in strength from the top of the lens to the bottom and multiple focal points in between. The upper part of the lens contains the distance power, the middle of the lens has the intermediate ranges and the lower portion, the reading part.
Below are the basic 3 regions of a varifocal lens:
Distance Zone: The ‘upper’ portion of the varifocal lens provides the ‘distance’ viewing area.
Intermediate Zone: The distance and reading areas are connected via a ‘corridor’ of intermediate powers and provides viewing for ‘mid-range’ vision.
Near/Reading Zone: The ‘bottom/lower’ portion of the lens provides the ‘close up/reading’ area
Varifocal Brands. We are not tied to any varifocal manufacturer, this means we can source any varifocal for you or recommend a selection of branded lenses fit for your purpose/ hobbies /occupation and lifestyle.