THE THREE TYPES OF LENSES
An eye examination will determine your prescription and which type of lenses you require. Usually you will be advised wether you need spectacles to correct either distance, intermediate or near vision, or a combination of the three:
- Distance vision lenses: general purpose wear for driving, watching television, the cinema or walking.
- Intermediate vision lenses: reading distance slightly further than arms length for looking at computers, reading music or shopping.
- Near vision lenses: close work for reading, iPhones or iPads, crafts and hobbies.
Single vision reading lenses (including frame from £29)
Single vision lenses are spectacle lenses that have one power throughout the whole of the lens. They will give you great vision for close work only, but as soon as you look ahead your vision will blur. This will result in you frequently taking spectacles on and off. Keep them close by so you don't lose them. Single vision lenses are suitable for all lens types, whether you need for distance, intermediate or near.
Single vision lenses are available in standard plastic, hi-index, photochromatic, polarised, and all tints and coatings.
Bifocal lenses (including frame from £49)
Bifocal lenses contain two lens powers in one lens. A large portion at the top of the lens allows you to see distance objects, while a smaller portion at bottom of the lens allows you to see near objects. However, it is possible to use different combinations, for example distance/intermediate or even intermediate/near. The reading segment on a bifocal is available in different sizes and shapes depending on your needs, including round, D-shaped and executive style (covering the full bottom portion of the lens). The reading segment will have a visible dividing line on the lens.
Bifocal lenses are available in standard plastic, hi-index, photochromatic, polarised, and all tints and coatings.
Varifocal lenses (including frame from £79)
Varifocal lenses have all three lens powers in one lens. This allows you to see clearly at all distances. The upper portion of the lens contains the distance prescription, this gradually increases in strength to give a full reading prescription at the bottom of the lens. The distance and reading areas are connected by a corridor, which provides an intermediate area. Varifocals look just like ordinary lenses as there is no visible line.
arifocal lenses are available in standard plastic, hi-index, photochromatic, polarised and all tints and coatings.
SightDirect supply 1.5 plastic lenses as standard. But with prescriptions over +/- 3.00 we recommend a thinner and lighter lenses
- Standard 1.5
- Thin 1.6
Up to 55% flatter, 40% lighter and 36% thinner than standard plastic lenses
Recommended for prescriptions over +/-2.00
- Very Thin 1.67
Up to 53% flatter, 45% lighter and 45% thinner than standard plastic lenses
Recommended for prescriptions over +/-4.00
- Thinnest 1.74
Up to 65% thinner than standard plastic lenses
Up to 42% thinner than 1.6 material
Up to 15% thinner than 1.67 material
Recommended for prescriptions over +/-6.00
Anti-reflection coating helps to improve both the vision through your lenses and the appearance of your lenses. Anti-reflection coatings virtually eliminate reflections on your lenses enabling 99.6% of light to reach your eyes. All anti-reflection coatings incorporate a hard coating to provide a tougher scratch resistant lens. Anti-reflection lenses are recommended for driving (especially at night), computer work or working under artificial lights. Anti-reflection coating makes your lenses seem “invisible” therefore improving the appearance of your spectacles.
Blue coated anti-reflection coating
The purpose of this coating is to filter harmful blue light emitted from artificial lighting, computers, tablets and smartphones without distorting colour vision.
OPTIONS FOR SUN PROTECTION
Sun tints protect the eyes from UVA and UVB as well as certain lights. They include:
- UV coating
- Tinted lenses
- Polarised lenses
- Photochromatic or Transitions lenses
Ultraviolet light (UV) is not only harmful to our skin but to our eyes as well. Overexposure to UV light is thought to be a cause of cataracts, retinal damage and other eye problems. Sunscreen will protect your skin from harmful UV rays and a UV protective coating on your lenses will block the same rays from damaging your eyes. Standard plastic lenses block most UV light but adding a UV coating will increase protection to 100%. A UV coating can be added to any lens. Some lenses including photochromatic/transition and high-index lenses plastic have 100% UV protection as standard.
Tinted lenses can reduce glare, improve contrast and enhance depth perception. Tints can range in depth. Choose a light tint with 10% light transmission factor (LTF) for cosmetic appearance or to reduce glare if you are light sensitive. Or choose a dark tint with 80% LTF if you require protection from a stronger sun. There are 3 colour options:
- Brown sharpens contrast and reduces glare. Brown is a good all purpose tint as it blocks out blue light, making it a good choice for driving and outdoor sport. A brown tint adds warmth to your vision.
- Grey allows the truest and most natural vision and colour perception. The neutral colour grey improves visibility and depth perception.
- Green transmits all colours evenly. It reduces glare while brightening shadows so it is a good all purpose tint.
Polarised lenses help eliminate glare, as well as improve contrast, visual clarity and comfort, while blocking 100% of harmful UVA and UVB light. Polarised lenses are the only lenses that can block blinding glare as they eliminate light from reflective surfaces such as roads, car bonnets and water; making them ideal for drivers, cyclists, fishermen and beach lovers. Polarised lenses are available in brown, grey and green, and they are available in single vision, bifocal and varifocal lenses. However, they can cause distortion when viewing digital displays, making some mobile phones, satellite navigation display and clocks difficult to read when viewed at an angle.
Photochromatic lenses, sometimes known as transition lenses, automatically adapt to changing light conditions. Lenses change from clear (when indoors) to fully dark (when in bright sunlight) making your vision more comfortable. When dark, lenses block 100% of UVA and UVB rays. Photochromatic lenses are available in brown, grey and green, and they are available in single vision, bifocal and varifocal lenses.