Critical Wavelength®
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Education is the key 
                        to protection!

UVA and solar aging

Many of the cutaneous signs associated with aging, such as wrinkling, are due largely to solar exposure.  Protecting individuals from photoaging is more difficult than sunburn prevention.

In photoaging, both UVA and UVB contribute to photoinduced damage such as oxidative damage and erythema. However, UVA has several unique characteristics that make it a suspect in chronic sun damage and photoaging.

Photoinduced changes (secondary to UVA exposure) in the dermis are thought to be involved in the formation of wrinkles that accompany aging. UVA effects on cytokine release and signal transduction pathways alter expression of enzymes that remodel the dermis. Quantitative and qualitative changes in dermal macromolecules such as collagen, glycosaminoglycans, and elastic fibers follow exposure to UVA.

Sunscreens with a higher SPF and with broad-spectrum protection against not just UVB, but UVA can help in both preventing photoaging and in repairing it. Research has shown that use of sunscreens shifts the balance of tissue remodeling toward net repair by preventing additional deposition of abnormal ground substance. 

Put simply, UVA rays are known to “turn on” enzymes that promote collagen breakdown while at the same time inhibiting enzymes that result in new collagen formation. It is vital that one use a sunscreen with at least a Critical Wavelength® value of 370nm or above.


In the image above, the collagen is damaged (purple) which contrast starkly to the healthy (pink) collagen (seen below). Whereas UVB rays produce largely epidermal damage, UVA rays penetrate deeper into the skin resulting in dermal damage. As one extends further into the long wavelength UVA range, the deeper the UVA rays penetrate into the dermis. It is vital that one knows the level of UVA protection, or Critical Wavelength®, if they want to protect the dermis from the solar damage. 

Without adequate UVA protection, one is slowly etching everyday into their skin with the fine lines, sunspots, wrinkles, loss of elasticity, and skin thinning all associated with solar aging. Given new technology together with knowledge of a product's critical wavelength this damage is now avoidable, and perhaps to a limited extent reversible.

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