Light therapy or phototherapy is a treatment for skin conditions such as Psoriasis and Mycosis fungoides that utilizes ultraviolet (UV) light waves for a set amount of time. Immune system cells in the skin are exposed to UV radiation which can help to treat skin conditions that are caused by an inflammation or overreaction of the immune system.
Skin phototyping is the classification of one’s skin sensitivity to UV light, which not only predicts the risk of photodamage and skin cancer but also estimates how much light therapy is safe for someone depending on their skin phototype. One of the main factors influencing skin tone is the amount and kind of epidermal melanin present. Two general categories of melanin exist, lighter pheomelanin and darker eumelanin. Compared to pheomelanin, eumelanin has a stronger photoprotective function. Darkly pigmented skin tends to have eumelanin, which is a good UV radiation filter while Fair-skinned individuals have higher levels of pheomelanin, which serves as a less effective UV filter. Prior to the 1960s, there was no standardized classification of UV sensitivity besides judgments purely based on skin tone and color which lacked the accuracy and specificity required for successful dermatological assessment.
The Fitzpatrick scale, developed in 1975 by American dermatologist Thomas B. Fitzpatrick aimed to improve on previous skin classification models by incorporating more than just skin color, including ethnicity, hair color, and UV sensitivity to sunlight as metrics for skin assessment.
The Fitzpatrick scale is widely used in modern dermatology but does present limitations. Since skin pigmentation, which is defined as a variable skin tone ranging from very light to very dark, does not correlate linearly with the susceptibility to develop skin cancers, a six-category scale is inappropriate for assessing the risk of skin oncogenic potential when outcomes such as “never burns” or “very rarely burns” associated with darker skin are evidently untrue. This subjective language presents a risk for inaccurate skin typing as terms (eg. burning and tanning) and time frames (eg. rarely or often) might mean different things to different people. The scale allows for self-reporting of skin types, which is much less accurate than a biological assessment by a trained dermatologist. Such self-reporting is influenced by community perception that leads to flawed typing. Additionally, when used for people with skin of color or those from non-Western cultures, the Fitzpatrick scale has been criticized for being ‘Anglo-Irish centric’ or ‘simply irrelevant.’ Fitzpatrick I–IV can be used in Europe to refer to the different skin tones that are typical of people with mostly European ancestry; brown to black skin can also be described by Fitzpatrick IV, V, and VI. These categories include people from central Africa, parts of South America, the South Pacific, Australia, and the Caribbean, as well as people with mixed ancestry who live abroad. People from various regions of Asia, North Africa, South Africa, Central America, and Southern America can therefore be classified as Type V. The vast variety of people around the globe included in just 2-3 skin types demonstrates a lack of inclusivity in the Fitzpatrick scale, and its limited value as a universal classification system.
In conclusion, the Fitzpatrick scale is not an accurate representation of universal skin classifications due to the many limitations it has which presents its own risks. Skin typing is used for medical light treatment and cancer risk assessments, giving a false sense of security to those using the scale. Instead of a surface-level scale, a genetic assessment of one’s skin type would be more effective in accurately determining one’s UV sensitivity.
