Choosing Sunglasses Lenses
When choosing lenses you should always ensure that your lens is optically correct, that is made to your specific eyesight requirements and made to a high standard. Low quality, cheaply manufactured lenses can often have imperfections which can lead to distortions in vision and even if they are small distortions, they can lead to discomfort, headaches and even nausea.
When choosing a lens material, you have several options, Glass, Plastic (CR-39), Polycarbonate or Acrylic. Glass lenses offer the best quality vision and are more scratch resistant. Downsides are that they weigh more, can shatter more easily and are more expensive than alternatives. Plastic CR-39 lenses are much lighter and thinner than glass lenses and also offer a high degree of impact resistances as do Polycarbonate lenses. Polycarbonate lenses are extremely impact resistant, much more so than any of the other materials, they also offer protection from UV rays as standard and as such make an excellent choice for sunglasses, kids glasses and protective eyewear. Acrylic lenses are the cheapest option and weigh very little however they are very prone to scratching and require special treatment to enable them to block UV rays.
Once you have chosen your material, you can move on to the lens color or tint. In general, the darker color the tint the more light will be absorbed. There are several common tints available:
- Gray: Gray lenses cause minimal color distortion and reduce glare whilst keeping vision as naturally as possible.
- Brown: Brown lenses cut out glare and offer good contrast whilst the darkness of the color reduces eye strain.
- Green: Green lenses are good in low light conditions where it enhances contrast and in high light conditions will reduce eye strain. This is considered the best all purpose lens.
- Orange: Orange lenses cut out a large amount of blue light and increase contrast thus enhancing details. Good for activities that are prone to high glare.
- Rose: Rose lenses give good contrast and glare protection. Rose lenses are good for daylight conditions.
- Yellow: Yellow lenses provide good contrast in low light conditions and are good in hazy or night conditions and in the skiing world.
The next step is to decide if you want a coating on the lenses, coatings can enhance certain features of your lenses or add an extra layer of protection. There are several options available, some of which are listed here:
- AR (anti-reflective) coating. This refers to various layers of metal oxides on both the front and back of the lens and as the name suggests is used to block out reflected light, reducing glare and halos.
- Photochromic. These lenses adjust to light conditions, darkening when it is bright and lightening when it is darker.
- Polarized. Polarized lenses consist of a filter between the front and back of the lens which stops the horizontal reflected glare given off by many surfaces.
- Mirror / Flash. This is a highly reflective coating that significantly reduces the amount of light reaching your eyes.
- Gradient. These are shaded from top to bottom and are commonly used in driving or flying to allow clear vision of the dashboard or controls.
- Scratch Resistant. A hard, clear coating is applied to the lens which offers a greater resistance to scratches. Many plastic lenses have a degree of protection already, notably polycarbonate lenses.
- UV Treatment. A coating that blocks UV rays from reaching your eyes.
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