E-SPF

UV rays penetrate the eye to different depths

UVA rays are mostly absorbed by the lens but a small portion reaches through to the back of the eye, the retina. UVB rays are mostly absorbed by the cornea, with some reaching the lens of the eye.

Research has shown that there is a correlation between UV exposure and a number of short-term and long- term ocular diseases and conditions such as photokeratitis, pterygium, cataracts and various forms of cancer. Cataracts represent the most significant public health impact.

A cataract is the opacification of the crystalline lens due to the accumulation of oxidized lens proteins. This causes blurry vision that can ultimately lead to blindness. Every year, millions of cataract surgeries are performed to restore sight.

UV radiation from both transmitted and reflected UV rays

Research shows that effective protection from the serious hazards of ultraviolet radiation requires that lenses protect wearers from both transmitted and reflected UV rays.

Measures have found that up to 50% of UV light reaches the eye from the back and sides of the lenses. The rear surfaces of antireflective lenses absorb visible light while UV rays continue to reflect into the eyes. Since this is invisible there is no natural defense like pupil contraction or squinting.

Lenses that totally block the transmission of UV rays can reflect UV rays into the eyes and communication about total UV protection of the lens, whether clear, photochromic or sunwear, typically only refers to transmission.

Even for sunglasses where standards exist today regarding UVA and UVB protection, only UV rays transmitted through the front surface are taken into account.

So your patients may not be receiving maximum UV protection with their lenses

Essilor developed the Eye-Sun Protection Factor (E-SPF) as a new standard certifying the global UV protection of a lens

Whether a clear, photochromic or sunwear lens, E-SPF includes UV protection against both transmitted and reflected UV rays, so now you can be sure your patients get the best protection.

E-SPF is a ratio of UV irradiance that compares protection with and without a lens and has been established using a series of experimental measurements. The measurements and calculation have been endorsed by Karl Citek, OD PHD FAAO.

Just as the skin care industry adopted an index to identify levels of protection against ultraviolet rays for the skin, E-SPF has been developed to bring a new standard in UV protection provided by lenses. This will help you recommend the best level of UV protection to your clients. As the index used to rate skincare and sunscreen products efficiency, the concept for the consumer is a very simple one: the higher the E-SPF value, the better the level of protection.