Lately, there has been a lot of talk about visible light and its effects on conditions like melasma. What is the effect on visible light on the skin? How well does sunscreen work to block visible light? What ingredients should you look out for? Is it worth considering wearing a visible light blocker each day? We will explore these questions and more in this blog.
The effects of visible light on skin darkening were reported in 2008 when a group at Henry Ford Hospital in Detroit, USA, reviewed our understanding of the biological effects of UVA light on our skin. Visible light caused redness, pigmentation, thermal damage and DNA damage in the skin. That same year, a group in Montreal studied the effect of inorganic sunscreens against blue light and showed that iron oxide at a concentration of 3.2% was an effective blocker of visible light. You can probably see where we are going with this post….
In 2010, the same group in Detroit, showed through their research that when visible light is shone onto the skin of those with darker skin types, it caused darker and most sustained hyperpigmentation than ultra-violet light A. When this study was published it was clear to all dermatologists who specialise pigmentation disorders and skin of colour, just how important this piece of knowledge was going to be for doctors and patients alike. It was clear that iron oxide was the key ingredient to help block visible light and hence help protect against hyperpigmentation.
In 2013, a well-designed study from our colleagues in Mexico demonstrated that when patients with melasma use iron oxide- containing sunscreen, their melasma improvements are superior.
Dr. Rodrigues states, “since 2013, I have been routinely recommending the use of iron oxide- containing sunscreens to my patients. I recommend it to all patients with pigment problems and all patients with Indian skin, Chinese skin, African skin and other patients with skin of colour and mixed ethnic backgrounds.” This is so important that she also states that she has “included the concept of visible light blockers in [her] lectures and publications on hyperpigmentation since 2013 because it is just so important.”
The recent flurry of discussion about this topic seems to have resulted from a recent publication by a pigment expert in the USA who has tested the ability of the ingredient iron oxide, to block visible light in patients with Fitzpatrick skin type 4 (Check out Dr. Michelle Rodrigues’ profile picture to see what skin phototype 4 looks like!). This study applied a non-tinted mineral SPF50+ sunscreen and three other sunscreens with varying concentrations of iron oxide to the back of the 10 subjects in this study. Visible light was then shone on all four sites and bare skin. Results showed less pigmentation in the areas that contained sunscreens with iron oxide compared with bare skin and non-tinted mineral SPF50+.
Iron oxide-containing sunscreens have not been easy to obtain in Australia until recently. Fortunately, we now have several brands including La Roche Posay with tint, Avene compact sunscreen, Propaira (tinted sunscreen) and others. You don’t have to spend a heap of money to get the coverage and protection you need. However, the next challenge is finding a colour, thickness and feel that suits your individual skin type. Most people with Asian and darker skin types will tend to like the one of those listed above. And if all else fails, consider a foundation on top of your sunscreen as this too will block visible light.
The information contained in this blog post is intended as a guide only and should not substitute seeking medical attention. Please see your healthcare provider for more information on suitability of products, treatments or procedures.