Special lenses are now available to provide filtration for reading glasses, night driving glasses, computer glasses, aviator glasses, sports specific sunglasses and other special purpose glasses.
The appropriate eye protection glasses can reduce the risks of cataracts and macular degeneration in later life. Ultraviolet (UV) rays in sunlight damage the cornea and retina. Good sunglasses can filter out UV rays completely. Intense light naturally causes the iris to close as far as it can as a prelude to squinting.
If there is still too much light, as there can be in the glare reflecting off snow or water, the retina can be damaged. Quality leading designer sunglasses can block over 90% of the light entering the eye to avoid damage.
Cheap, low quality sunglasses can be more harmful than no protection at all if they do not block the UV rays. They block some light causing the iris to open wider to compensate and this allows more UV rays to enter increasing the damage to the retina.
Beware of imitation designer sunglasses!
Often the frames will look almost exactly the same as the top brands, even down to copying the logo but the lens will be nothing more than thin plastic with a tinted coating offering no protection at all and likely to make matters worse over time.
The top designers products will have various types of lenses offering good protection but it is as important to consider the features of the lenses as it is to decide on their virtues as a glamorous fashion accessory. Those requiring eyeglass lenses to correct visual impairement can incorporate their prescription into their ‘eye doctors’ advice.
Types of Light Filtering Sunglass Lenses
- The skin, hair and eyes contain a pigment known as melanin that provides us with protection against the harmful ultraviolet rays in sunlight.
- Recent advances in protective lens technology have enabled the properties of melanin to be incorporated in good quality eyeglass lenses and should be the choice for sports wear where there is any chance of an impact damage to the eyes or area immediately surrounding.
- CR-39 is a trade name for the optical industries’ standard plastic lens material. The lenses are considerably lighter and less breakable than glass but not as resistant to impact as polycarbonate.
- Glass has the best optical clarity of all optical lenses and has the best resistance to scratching.
- Glass is hardened to meet US Food & Drug Administration impact resistance standards.
- Many leading polarized sunglass manufacturers use glass lenses in some of their models.
- Polarized lenses filter out reflected light and glare typically from water and snow.
- They are ideal for activities such as sailing, fishing, driving or any other situation where glare may be encountered.
- They are particularly useful for winter sports enthusiasts.
- Considered to be the best lenses for eliminating UV rays and glare and is achieved by blocking light from certain angles while allowing light to pass through at other angles.
- The polarization effect shuts out all undesirable light and allows 1005 harmless light pass through the lenses.
- Polarized Lenses are also available with an anti reflective (AR) ultra thin coating on the back for increased clarity and reduced glare from the aback of the lens.
- Photo chromatic Lenses have a tint that changes according to the intensity of the light.
- They darken in bright sunlight and become lighter in color as the intensity of light diminishes allowing a reduction in eyestrain.
- This process is not instantaneous although recent developments have speeded up the change.
- These lenses are generally made of hardened glass to provide the best results and are an excellent option as visual impairment corrective lenses.
- Mirrored Lenses have a coating applied to the front surfaces of the lenses that in effect, causes them to act like a two-way mirror.
- The mirror coating reflects light waves from sources of high glare such as snow water or ice preventing them from passing through to the eye.
- Virtually any type of lens can be mirror coated and many have an anti reflective (AR) coating on the back to reduce back glare.
- Mirrored lenses are darker than other lenses and hide the eye from outside.
- For special sporting activities such as skiing sub aqua diving, snorkeling and swimming the goggles have lenses that can have a clear coating applied, which will prevent the fog or mist forming on the inside due to condensation, in other words, sport specific.
- It is also possible to find sunglasses which a have a ‘no fog’ coating for active sportswear.