Ultraviolet radiation (UVR) damages the eye and causes photoaging and cancer of the eyelids. Daylight exposes us to harmful levels of
UVR at any time of year from mid morning to late afternoon, even when people normally do not think to wear sunglasses. Spectacles can provide significant eye protection from UVR. Yet the most popular spectacle lens materials do not completely block UVR. Some ophthalmic lens standards ignore the hazard of UVR wavelengths longer than 380 nm, creating a UVR protection gap. ZEISS has re-engineered its most popular lens materials to provide full protection from harmful UVR.

 

Problem

Ophthalmic lens standards have not kept up with the latest research on the damaging effects of low-intensity UVR exposure. The ISO 8980-3 lens standard defines the UVR spectrum as stopping at 380 nm, even though the hazard evaluation standard that it relies upon defines a UVR hazard up to 400 nm. Forty percent of UVR in daylight lies between 380 and 400 nm.

Eyeglass wearers are aware that UVR is bad for the eyes, but many are told – or assume- that their eyeglasses already provide complete UVR protection. But: almost 2/3 of daylight UVR lies in wavelengths not fully blocked by the most common clear spectacle lens material (e.g. 1.50 index plastic passes a large amount of UVR over the region between about 350 and 400 nm),

approximately 40 % of daylight UVR lies in wavelengths not fully blocked by materials that can claim “100 % UV protection” by blocking to 380 nm (e.g. polycarbonate and 1.60 index plastic passes a significant amount of UVR below 400 nm).

Photoaging of skin can be prevented by sunscreen, but many people refuse to put sunscreen on their eyelids. Long wavelength UVR up to 400 nm penetrates deep into the skin, damaging mitochondrial DNA in dermal fibroblasts. The type of damage causes deep wrinkles and loose skin.

Skin cancers of the eyelid account for 5 to 10 % of all skin cancers and because of the local anatomy, they may easily spread to the rest of the body. UVR also causes cataracts. It is becoming apparent that long-wavelength UVR accelerates pre-cataract changes. These changes increase light scatter, reduce contrast and mute colors long before surgery is necessary. In light of these facts there is no good reason for spectacle lenses to let any UVR through.

Solution

By far the greatest potential UVR exposure to lens wearers comes from light passing through their lenses from the forward direction. Most of the UVR that could reach the eye and eyelids strikes the spectacle lens first. It is important that spectacle lenses render it harmless. The strongest standard for UVR protection is currently defined for sunglasses, not clear lenses. The Australia/New Zealand Sunglass Standard applies the ICNIRP UVR hazard over the full spectrum of UVR, up to 400 nm.

ZEISS UVProtect achieves the maximum level of protection, calculated according to that stringent sunglass standard, providing complete UVR protection in a clear lens. In fact, ZEISS scientists have found ways to engineer each of the most common clear plastic lens materials to absorb the full spectrum of harmful UVR, without troublesome changes to visible light (e.g. color and clarity).

The redesigned lens materials do not result in a noticeable change in appearance. In a ZEISS consumer study, consumers were shown standard plastic lenses and ZEISS 1.50 UVProtect lenses in a randomized and masked presentation. Looking through eachlens in both outdoor and indoor settings, a majority actually preferred vision through ZEISS UVProtect.

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