Light Therapy & Vitiligo

What is UV? What is UVB?

UVB means ultraviolet B radiation. It is also referred to as a medium wave.

The wavelength of UVB light range from 280 nm to 315 nm. It is found in between UVA or long-wave (also called black light) and UVC or short wave.

Ultraviolet radiation is the type of electromagnetic radiation found between visible light and X-ray. The ultraviolet spectrum occupies the range of wavelengths between 10 nm and 400 nm.

Ultraviolet light is just beyond the violet part of visible light (the color with the shortest wavelength in the visible light spectrum). Although it is invisible to humans, it can be perceived by several birds and insects.

The major natural source of ultraviolet radiation is sunlight. This radiation can make materials glow and this fluorescence is one presentation of the chemical reactions triggered by ultraviolet light. While the ultraviolet radiation between the wavelengths 10 nm and 120 nm can ionize living tissue and is overtly destructive, the rest of the ultraviolet spectrum is mostly safe.

However, even the safe spectrum of ultraviolet radiation can damage the skin. For example, ultraviolet irradiation in sunlight can cause sunburn and even penetrate the skin deep enough to damage genetic materials.

The ozone layer blocks most of the ultraviolet radiation coming from the sun that is above UVB radiation. However, some of this still get through.

Only 3% of the total energy in incident sunlight is due to ultraviolet radiation.

Effects of UV and UVB radiations

While ultraviolet radiation can damage the skin, they also have beneficial effects such as stimulating the production of vitamin D (the peak production of which occurs within the UVB spectrum).

When the skin is exposed to UVB radiation, the conversion of cholesterol to vitamin D proceeds rapidly. The rate of production of vitamin D following UVB exposure can go up to 1,000 IU per minute.

However, long exposure to UVB radiation can cause sunburn, skin cancer, and direct DNA damage. Sunscreens are specifically formulated to block UVB radiations although they now contain active agents (such as zinc oxide, titanium dioxide, and avobenzone) that also block or absorb UVA radiation.

The SPF rating of sunscreen relates to how effectively they block UVB radiation.

The direct damage of DNA is, however, a property exploited by the skin tanning industry. When the skin is exposed to UVB radiation, the limited damage done to the DNA during a visit to a tanning salon can induce a longer-lasting tan.

The acquired tan is a response from the melanocytes. These are the special skin cells responsible for producing melanin, the skin pigment.

UV radiation is also being used for treating certain skin diseases including vitiligo and psoriasis.

UVA was once the light treatment of choice but its use has been surpassed by UVB. This is because of the clear benefits of UVB therapy over PUVA (psoralen and ultraviolet A therapy).

What is Narrow-Band UVB?

Narrowband UVB is a very short wavelength, the tailored spectrum of UVB.

It is a new technique used to treat vitiligo and it is currently the preferred UV therapy for vitiligo. Unlike broadband UVB lamps which produce ultraviolet radiation between the wavelengths 280 nm and 330 nm, narrowband UVB lamps emit UVB light of wavelength, 311 – 312 nm.

By cutting out UVA radiation and even most of the UVB spectrum, narrowband UVB produces far fewer side effects. Also, it is more specific than other UV therapies.

Studies have shown that the portion of the UVB spectrum that gives the best results in vitiligo treatment is between 295 nm and 313 nm. However, below 300 nm, UVB is associated with an increased risk of severe skin burn, erythema, and skin cancers.

Therefore, the 311 – 312 nm range is the right balance of safety and effectiveness.

Narrowband UVB is recommended for vitiligo patients in which the white patches cover more than 20% of the body area. It can be done at home or in a dermatologist’s office.

At the doctor’s office, a full-length body cabinet is used for narrowband UVB treatment. However, a full-length panel or handheld device can be used at home. Unless the vitiligo spots are localized, the UVB panel is a more efficient home treatment device than the handheld device.

Narrowband UVB is safe for use for children. It is usually combined with other vitiligo treatments.

The full body units may cause the skin to tan and increase the contrast between the vitiligo spots and the normal, pigmented areas of the skin. However, this effect is actually beneficial since it stops the spread of those spots.

Most people report positive results after 30 – 60 narrowband UVB sessions. It is recommended that at least a day should be allowed between successive UV treatment sessions. Therefore, no more than 3 sessions are advised per week.

Eye protection should be worn during each session of narrowband UVB treatment.

Narrowband UVB is most effective for treating non-segmental (also called generalized) vitiligo. UVB treatment usually produces less impressive results with localized or segmental vitiligo.

Therefore, the preferred light therapy for segmental vitiligo is excimer laser phototherapy.

How Narrow Band UVB Works for Vitiligo

There are various mechanisms by which narrowband UVB works in the treatment of vitiligo. Most likely, the positive results seen are a combination of these effects.

First, narrowband UVB like all light therapy can suppress the immune system. Since vitiligo is commonly described as an autoimmune disease, this side effect of ultraviolet irradiation is useful for preventing the autoimmune destruction of melanocytes.

By blocking the cells of the immune system, narrowband UVB allows more melanocytes to thrive.

While all light therapies can suppress the immune system, most of them also damage the skin. Narrowband UVB, however, uses light in a safe, narrow range of the ultraviolet spectrum. Therefore, it can stimulate increased production of melanin by preventing an autoimmune attack on melanocytes long before it can cause sunburn or DNA damage in the skin.

Another mechanism by which narrowband UVB works for vitiligo is in the increased production of vitamin D.

UVB radiation is especially known to accelerate the production of vitamin D in the skin. Therefore, repeated exposure of the skin to UVB radiation increases the levels of vitamin D in the skin.

Vitamin D is an important supplement in the treatment of vitiligo. Some of the most important vitiligo drugs are vitamin D analogs.

Vitamin D has many medicinal properties that can help stop the depigmentation of the skin and even promote the repigmentation of vitiligo spots.

For example, vitamin D is an immunomodulatory agent. Therefore, it blocks the release and activation of immune cells such as T cells (reported to contribute to the autoimmune cause of vitiligo) and inflammatory factors such as tissue necrosis factor-alpha (TNF-alpha).

Furthermore, vitamin D promotes the rapid maturation of melanocytes.

In this way, it increases the rate at which new melanocytes replace dying ones. This vitamin has also been shown to possess some antioxidant properties sufficient enough to reduce oxidative stress in the skin and prevent the destruction of melanocytes by reactive oxygen species and other harmful free radicals.

Studies on Narrow Band UVB Vitiligo Therapy

The safety and efficacy of narrowband UVB therapy in the treatment of vitiligo were studied and reported in a 2009 paper published in the Indian Journal of Dermatology, Venereology, and Leprology.

In that study, 150 vitiligo patients aged between 3 and 70 years were treated with increasing doses of narrowband UVB radiation twice weekly for up to a year.

The study results showed that significant repigmentation of vitiligo spots was evident in the participants with good compliance to the UVB treatment and that the repigmentation was stable in most of the patients during the 6-month follow-up period that followed the treatment duration.

A 2002 study published in the journal Acta Dermato-Venereology examined the benefits of combining folic acid and vitamin B12 supplementation with UVB treatment of vitiligo.

The researchers recruited 27 vitiligo patients who were divided into 2 groups.

One group received UVB treatment alone while the other group got a combination of UVB and vitamin supplements. The treatment duration was 1 year and UVB irradiation was given 3 times every week.

The results showed that 92% of the patients showed near-total repigmentation. However, supplementation with folic acid and vitamin B12 did not produce significant improvements in results.

In a similar study, the efficacy of combining tacrolimus ointment with narrowband UVB therapy was studied in 40 vitiligo patients.

The patients were given total body narrowband UVB irradiation, 2 – 3 times per week. They were also instructed to apply 0.1% tacrolimus ointment to the vitiligo patches on one side of their bodies and a placebo containing only the base of the ointment to the patches on the other side of their bodies.

The results showed that there was more repigmentation on the sides on which tacrolimus ointment was applied more than the side that only got narrowband UVB. The repigmentation in the patients was also stable during the 3-month follow-up period after the treatment.

This study showed that the results of narrowband UVB treatment can be improved with a topical agent such as tacrolimus ointment.

Other studies have found narrowband UVB treatment effective for treating vitiligo in specific groups of patients including children as well as people with skin phototypes IV and V.