Different wavelengths of the electromagnetic spectrum, such as – ultraviolet (UV) A and B, visible light (VL) and infrared radiation, have varying penetration depths in the skin. The extent of dermatological damage and pigmentation incurred depends on factors like skin phototype and sun exposure.

It is important for all skin types to use sunscreen, but the specific need for protection from these wavelengths varies based on the phototype and various dermatological conditions. The 30th European Academy of Dermatology and Venereology (EADV) virtual congress, which was held in Sept-Oct 2021, included sessions on topics like skin phototypes, photoprotection, photoaging, photodermatoses, pigmentary disorders, inflammatory skin disorders and skin cancer, presented by leading dermatology experts. The sessions discussed the main points related to these topics, including data on a UVA1 filtering agent called methoxypropylamino cyclohexenylidene ethoxyethylcyanoacetate (MCE), also known as Mexoryl 400, which was presented as an advancement in photoprotection.

Important topics explored in the ‘Revolution in Photoprotection’ presentation were:

• Skin phototypes: The risk and effects of UVA, UVB and VL on the skin are influenced by skin phototype, geographic location and lifestyle. Darker skin is prone to pigmentation, while lighter skin is more susceptible to sunburn, DNA damage, skin cancer and aging. Although UVA-1 harbors less energy than UVB, it constitutes a significant portion of UV exposure, can penetrate through windows, and has been linked to inflammation and immune suppression. Meanwhile, UVB directly affects melanocytes and activates pigmentation processes. VL in the blue/violet spectrum can induce hyperpigmentation, particularly in darker skin types.

• Photoprotection: Photoprotection is important for all skin types. Sunscreen formulations provide UVB protection based on the sun protection factor (SPF) and UVA protection based on the UVA protection factor (UVA-PF) and critical wavelength. There is currently no standard method to portray sunscreen efficacy against VL, but chemical filters and inorganic sunscreens containing iron oxides can provide UVA1 and VL protection. The filter MCE (Mexoryl 400) has shown promising effects in protecting against UVA1 and reducing pigmentation.

• Photodermatoses, hyperpigmentation and photoaging: Photodermatoses, including conditions like – polymorphous light eruption, chronic actinic dermatitis, solar urticaria, drug-induced photosensitivity and erythropoietic protoporphyria, require protective measures such as seeking shade, wearing photoprotective clothing and applying a broad-spectrum sunscreen with at least SPF30+. Individuals with solar urticaria and cutaneous porphyrias are recommended to use tinted or colored sunscreens for additional protection. Using a balanced SPF50+ and UVA-PF 21 sunscreen is advisable for preventing pigmentation and hyperpigmentation induced by UVA, VL and UVB. Sunscreen use has been shown to protect against photoaging and age-related hyperpigmentation in studies involving elderly individuals.

• Skin inflammatory disorders: Candiani discussed the photoprotection requirements for various skin inflammatory disorders. While sun exposure can be beneficial for individuals with atopic dermatitis and psoriasis, some patients may experience photoaggravation. Atopic dermatitis patients should avoid using sunscreen on weeping, moist or scarred lesions, while psoriasis patients should use a broad-spectrum, SPF50+ sunscreen with high UVA protection to prevent Koebnerization and photoaggravation. For acne-prone individuals, a non-comedogenic UVA/UVB sunscreen that does not interfere with topical acne medication is recommended; daily use of a broad-spectrum SPF30+ sunscreen can help prevent rosacea triggers.

• Skin cancer: Sun exposure and sunbed use are associated with an elevated skin cancer risk. Sunscreen use is effective in reducing melanoma rate and is likely to reduce the risk for squamous cell carcinoma––emphasizing the importance of sunscreen as a critical component of skin cancer prevention campaigns. Sunscreens with higher SPF, particularly SPF50+ for fair-skinned individuals, are recommended for melanoma prevention, whereas SPF50+ with a lower SPF/UVA-PF ratio is recommended for preventing basal cell cancers, actinic keratoses and squamous cell cancers. Protecting children from sunburn is crucial in reducing the risk of developing melanoma later in life.

Source: EMJ Dermatol. 2022;10[(Suppl 3):2-8