How to choose the best sunscreen, Broadway, Sydney

Dermatologists recognize that the most potent cosmeceutical on the market today that’s proven to prevent and reverse the signs of aging is sunscreen.[1]

Lifelong exposure to the sun accelerates the skin’s intrinsic aging process and leads to photo-ageing, which is characterized by wrinkles, abnormal pigmentation. laxity, roughness, sallowness and broken capillaries. Severe photo-damage may cause sun spots and malignancies. Sunscreens prevent photo-aging and photo-carcinogenesis (cancer from the sun), and should be the cornerstone of any skin care regimen.

Sunscreens can be added to facial moisturizers or cosmetics for daily protection, or they can be included in specially designed formulations that resist removal by water or rubbing to provide recreational protection.

There are two main types of radiation, UVA and UVB radiation - UVB radiation causes sunburn and UVA radiation causes premature aging and skin cancer. It is important to know that not all sunscreens have the necessary ingredients to protect the skin from both these radiations. "Broad spectrum" protection is achieved though combining different ingredients that each block different parts of the radiation spectrum.

There are two basic categories of sunscreen. - chemical blockers and physical blockers. Chemical blockers absorb short wave UVB light and prevent it penetrating the skin. They therefore protect from sunburn, but offer virtually no protection against premature aging and skih cancer.   Such blockers include PABA esters, avobenzone, and cinnamates.

Sunscreen with a sun protection factor (SPF) rating only indicates protection from UVB, which means that a sunscreen with an SPF of 100 or more offers virtually no protection from ageing. 

Physical blockers act exactly as the term suggests. They form a physical barrier between your skin and the sun, much like a T-shirt and hat. They  contain fine powders of zinc oxide or titanium dioxide that absorb, reflect or scatter light, bouncing it away from the skin. Though they do not discriminate between UVA and UVB, to provide adequate protection they have to be so thick and difficult to apply that they would be  unacceptable for everyday use. Think Shane Warne's fluoro lips on the cricket ground.   This is why combinations of chemical and physical barriers provide the best protection while preserving cosmetic elegance.

• broad spectrum protection across all ultraviolet (UV) radiation.
• lightweight, moisturizing and suitable for all skin types.
• cosmetically elegant and non whitening.

At Heber Davis we recommend Ultraceuticals Protective Daily Moisturiser SPF 30+ because it’s an easy to use moisturizer that that contains both chemical and physical screening properties that  together protect against  the entire UVA and UVB spectrum.

It’s important to apply your sunscreen correctly. SPF measurement is based on sunscreen applied at a concentration of 2 mg/cm². Studies show that most people apply a layer as thin as 0.5 mg/cm², resulting in an SPF significantly lower than stated on the label, and therefore not providing adequate sun protection.[3]

Sunscreen should be applied to the face and other exposed skin every morning, rain or shine, whether you intend to be indoors or not, as follows: After washing, apply a thin layer of sunscreen or daily moisturizer with an SPF and allow it to dry; then follow with a second layer. If outdoors, sunscreen application should be repeated every 4 hours and immediately after excessive perspiration and swimming.

Avoidance

Sun protection starts with avoidance of peak solar radiation, which occurs between 10:00 AM and 2:00 PM. Modifying outdoor behavior and wearing sun-protective clothing are more effective preventive measures than using sunscreen.

Clothing and Hats

Clothing and hats are an important method of sun avoidance though the degree of protection varies from garment to garment and between fabrics. Gambichler et al showed that 1/3 of summer clothing provided poor protection from UV radiation, and only 75 % of fabrics were able to deliver a sufficient degree of protection. [4]

Hats play an important role when sun exposure is unavoidable. Although baseball hats may be in vogue, they protect only the forehead and nose, leaving the cheeks, chin, and neck exposed. For total facial protection, the best hat is one with  at least  a 7 cm wide brim. 

The FDA-approved technique for assessing the efficacy of sunscreens and sun-protective clothing yields a number called the sun protection factor (SPF) rating. The SPF rating is calculated by comparing the amount of time necessary to produce sunburn on protected skin to the amount of time necessary to cause the same reaction on unprotected skin. For example, if  burning normally requires 10 minutes of midday sun exposure, a sunscreen with SPF 15 will prolong this time by a factor of 15, thereby rendering protection for 150 minutes. The SPF determination applies to UVB radiation only.

Normal clothing may provide SPF ratings between 6 and 15, which drops below a rating of 5 once the fabric becomes wet. Sun-protective clothing and fabrics offer SPF 30 or higher. [5]

As cosmetic physicians, we tend to concentrate on the harmful effects of UV exposure to the skin. However, acute and chronic damages from UV rays to the eyes are equally striking. Aside from the development of squamous and basal cell cancer on the eyelid and periorbital skin, UV exposure can also damage the cornea, conjunctiva, lens and retina.

Sunglasses can protect the eye from UV damage, as well as from squinting, which encourages the development and progression of crows feet and frown wrinkles. Aside from their cosmetic quality, the ideal pair of sunglasses should block all UV rays while not sacrificing the transmission of visible light. Wearing such a pair of sunglasses diminishes the amount of visible light, which can disable the squinting mechanism and dilate the pupil.

Although the composition of lenses and the degree of UV protection are important, the shape and coverage of the sunglasses are perhaps more critical. Most ocular damages from UV radiation result from scattered and reflected light from the periphery. In extreme conditions, indirect UV rays bounce off the ground, snow, water, and sand. Hence it is crucial that an ideal pair of sunglasses is wrapped closely to the eye. Unfortunately, most sunglasses are designed to be  fashionable, and only the anterior and superior sides of the eyes are protected.

For the same reasons, the important times to wear sunglasses should also be emphasized. Skin safety campaigns instruct the public to stay indoors when the sun is overhead and most intense and encourage outdoor play during the morning and evening. By extension, many people suppose that eye protection can be ignored or neglected during these off-peak hours. In fact, most eye damage occurs during the morning and late afternoon when the sun’s rays are parallel to the pupil axis. During the peak hour, the brow ridge and eyelid shield the eye from the UV rays. In addition, the squinting mechanism minimizes area of exposure on the ocular surface, and the pupil contracts to reduce UV transmission. In contrast, during the off-peak hours, the UV incident angle is low and the UV rays bypass the defense of the brow ridge and eyelid. In addition, the squinting and papillary constriction mechanisms are not initiated because the light intensity is weaker. Hence sunglasses should be worn at all times during daylight hours to ensure adequate protection.

[1] Christine M. Choi, MD, and Jeffrey S. Dover, MD, FRCPC, FRCP (Glasg)Journal Watch Women's Health,December 21, 2006

[2] Wang, S et al, Dermatologic Therapy, Vol. 23, 2010, 31–47

[3] Wulf HC et al. Sunscreens used at the beach do not protect against erythema: A new definition of SPF is proposed. Photodermatol Photoimmunol Photomed 1997 Aug; 13:129-32