What is Phototherapy Used to Treat?
Phototherapy is a form of treatment that makes use of a distinct type of light, apart from sunlight. It is also known as heliotherapy or light therapy. Dermatologists consider phototherapy to be safe when used correctly.
Certain skin conditions are treated with phototherapy. In this treatment, the skin is exposed to an ultraviolet (UV) light for a set amount of time. When combined with a medication called psoralen, the procedure is known as psoralen UVA (PUVA).
UV light shuts down immune system cells in the skin. It can help in skin conditions that are caused by an overreaction of the immune system. Skin conditions that are treated with phototherapy include eczema, psoriasis, and vitiligo.
UV Light and Seasonal Affective Disorder
Seasonal Affective Disorder (SAD) happens around the same time each year. It usually starts in late fall and ends in the spring. The lack of natural light can increase the probability of experiencing depression. Some of the symptoms for SAD include eating more, fatigue, irritability, heavy feeling in your extremities, and sleepiness among others.
Scientists do not completely understand how light therapy affects your mood if you have SAD. However, studies have shown that bright light jumpstarts an internal clock in your brain that controls your circadian rhythms over the course of a day. One function of that brain clock is to manage your mood.
How Does Phototherapy Work?
Phototherapy uses UV light, which is also found in sunlight. It can also be used in combination with medications applied on the skin to treat certain skin conditions.
Phototherapy can be administered to a specific area of the body or to the entire body if more than 5% of the skin is affected.
Types of Phototherapy
Ultraviolet B (UVB)
UVB phototherapy is further categorized into two types: broadband and narrowband. The difference is that narrowband UVB gives off a shorter wavelength of UV light.
Psoralen Ultraviolet VA (PUVA)
This type of phototherapy treatment uses UVA light and an oral medication called psoralen that makes your skin more sensitive to light.
Phototherapy equipment come in the form of narrowband UVB lamps, panel radiators, whole body cabins, and whole body panels.
Phototherapy lamps are small enough to help avoid unnecessary irradiation of unaffected skin, but care is needed to avoid over- or under-dosing at overlap areas.
Panel irradiators are used for the treatment of palmar and plantar skin.
Whole body cabins contain 1800 mm long fluorescent tubes that line the walls in front of reflective metal surfaces, enabling them to achieve greater dose uniformity and greater treatment efficiency.
Calibration and dosimetry are done by dose calculation and designated patient irradiance. These values are important for the determination of irradiation by UV unit at regular intervals. The mean UV irradiance in whole body cabinet to which a patient is exposed is called designated patient irradiance (DPI), and the irradiance is measured at 12 sites of the body at posterior, anterior, and both lateral positions.
What to Expect with Phototherapy
It may take one to two months of steady treatment with phototherapy to start to see improvement in skin diseases.