A proposed UVR protection factor for sunglasses

Ultraviolet (UV) transmittance characteristics of daily disposable and silicone hydrogel contact lenses

The ultraviolet (UV) transmittance spectra of daily wear hydrogel and disposable silicone hydrogel contact lenses were measured. Average transmittance percentages were calculated for each lens for the entire UV spectrum and individually for the UVC, UVB and UVA portions of the spectrum. The significance of the differences in transmittance spectra obtained for the lenses was analysed using a one-way ANOVA planned comparisons test (alpha=0.05). The transmittance data were then used to calculate a UV protection factor (PF) for each contact lens brand tested. The PFs for 1-DAY ACUVUE MOIST (6.22), ACUVUE ADVANCE (10.02) and ACUVUE OASYS (11.96) contact lenses show that these contact lenses have superior UV-blocking capabilities. The PFs for Focus DAILIES (1.79), SofLens 1-day disposables (1.72), NIGHT & DAY (1.84), O2 Optix (1.99) and Purevision (2.62) show that these contact lenses posses more modest UV-blocking characteristics. This paper reviews the importance of protection of the anterior ocular surface from UV damage and quantifies the protection afforded by selected commercially available disposable contact lenses.

Sunglasses and sunglass standards

Sunglasses and sunglass standards are reviewed from the point of view of the history of sunglasses and the development of sunglass standards. The need for eye protection from solar radiation is discussed and the provisions of the various national sunglass standards are discussed in relation to that need.

Nitric oxide-mediated depletion of Langerhans cells from the epidermis may be involved in UVA radiation-induced immunosuppression

Ultraviolet A (UVA) irradiation of the dorsal skin of mice reduced the contact hypersensitivity (CHS) response and the density of epidermal Langerhans cells (LC). The roles of nitric oxide (NO) and reactive oxygen species (ROS) in these biological effects of UVA were investigated. Topical application of N(G)-monomethyl-L-arginine acetate, an inhibitor of NO production, 2,2'-dipyridyl, an iron chelater, or 4-hydroxy-tempo, a superoxide dismutase mimicking agent, inhibited UVA-induced suppression of the CHS response. N(G)-monomethyl-L-arginine acetate but not the ROS inhibitors prevented UVA from reducing LC numbers in the epidermis. This suggests that NO but not ROS produced in response to UVA mediates a depletion of LC from the epidermis, probably by signaling these cells to migrate from the skin. This could be responsible for UVA-induced immunosuppression. UVA-induced ROS can also cause immunosuppression, but by a different mechanism. Agents that inhibit or modulate NO or ROS production may be useful for preventing damage caused by the UVA component of sunlight to the skin immune system.

Protection against solar ultraviolet radiation

Interest in protection against solar ultraviolet radiation (UVR) among the general public in Australia has been increasing steadily as a result of the 'SunSmart' campaigns run by the various state cancer councils. This increasing awareness is due in part to the requirements for occupational protection of outdoor workers and to provision of UVR protection for the recreational market. Behaviour outdoors can significantly affect exposure to solar UVR and use of items of personal protection can provide a substantial reduction in the UVR dose received. The protective properties of sunscreens, sunglasses, hats and clothing against UVR have been the subject of considerable research for some time, and over the last few years interest has extended to the provision of shade structures and the UVR protection provided by various commonly used materials. These materials include shadecloth, plastics, glass, windscreens and applicable tints. Australia has rigorous standards covering protection and UVR, in particular for sunscreens [Standards Australia/Standards New Zealand, Sunscreen products-evaluation and classification, Report No. AS 2604, Sydney/Wellington, 1993.], sunglasses [Standards Australia, Sunglasses and fashion spectacles-nonprescription types, Report No. AS 1067.1, Sydney, 1990.], protective eyewear [Standards Australia/Standards New Zealand, Eye protectors for industrial applications, Report No. AS/NZS 1337, Sydney/Wellington, 1992.] and shadecloth [Standards Australia, Synthetic shadecloth, Report No. AS 4174, Sydney, 1994.]. Compliance with the sunglass standard became mandatory in 1988 and UVR protection provided by sunglasses has increased substantially since then. In July 1996 a standard on 'sun protective textiles' [Standards Australia/Standards New Zealand, Sun protective clothing-evaluation and classification, Report No. AS/NZS 4399, Sydney, 1996.] incorporating ultraviolet protection factors (UPFs) and a rating scheme with protection categories, was introduced; this was the first of its kind in the world. Australian Radiation Laboratory (ARL) UPF swing tags with UVR protection advice from the Australian Cancer Society on the reverse side are used to denote the amount of protection against solar UVR provided by clothing. To date in excess of 5 million ARL swing tags have been issued. Work on the various standards is continuing. The maximum allowed 'sun protection factor' (SPF) limit for sunscreens may be increased to SPF 30 + in the near future, and additions to the sun protective textiles standard are also planned. This paper discusses measurement methods, results, the rationale used in formulating the Australian Standards and the current state of UVR protection in Australia.

Sunscreen protection of contact hypersensitivity responses from chronic solar-simulated ultraviolet irradiation correlates with the absorption spectrum of the sunscreen

This study compares the ability of two ultraviolet (UV) B-absorbing sunscreens, 2-ethylhexyl p-methoxycinnamate (2-EHMC) and 2-ethylhexyl p-aminobenzoate (Padimate O), and two physical sunscreens, microfine titanium dioxide (MTD) and zinc oxide, to protect the skin immune system from chronic (4 weeks) solar-simulated UV irradiation. Mice were exposed to suberythemal doses of UV before assessing local and systemic immunosuppression and tolerance to a contact sensitizer. Using a UV protocol that induced local but not systemic immunosuppression or tolerance in BALB/c mice, it was shown that Padimate O made the immunosuppression worse, whereas 2-EHMC and MTD protected the immune system. When the cumulative dose was increased by 12.7%, causing systemic immunosuppression and tolerance, none of the sunscreens protected from immunosuppression, but 2-EHMC provided partial, and MTD gave complete protection from tolerance. To examine this apparent lack of protection from systemic immunosuppression, C3H/HeJ mice were used. These mice had a minimal erythema dose similar to that of the BALB/c mice but were systemically immunosuppressed, with only 44% of the UV dose required to immunosuppress BALB/c mice. 2-EHMC provided some protection, whereas MTD provided complete protection from systemic immunosuppression in C3H/HeJ mice. Hence, sunscreens can protect from local and systemic immunosuppression, although this protection is limited and is not related to the sun protection factor of the sunscreens or the minimal erythema dose of the mouse strain. Instead, protection seems to be related to the sunscreens' having a broad absorption spectrum.