What is Phototherapy?
Light is made up of energy particles, so-called photons, that travel in a wave form. Just like when a pebble is dropped in a container of water, and as a result a wave is generated that transmits a portion of the energy that was moving the pebble, so does light that is generated from a source travels in a wave format, having a wavelength and a frequency. Frequency means how many oscillations there are per second. The cells on the back screen of our eyes, i.e., the retinal cells, detect light with wavelengths in the range of 390 nanometer (nm) to 700 nm. The invisible light with wavelengths of 280 nm to 390 nm that reaches the surface of the earth is classified as ultraviolet light. Although our eyes cannot detect this spectrum of light, ultraviolet light plays a key role in biochemical reactions to produce vitamin D along with the feel-good compounds that are called endorphins in our skin. Ultraviolet light rays induce deleterious binding of certain key components of the DNA molecules in our skin cells (keratinocytes), pigment cells, and immune cells that home within the skin.
The ultraviolet (UV) light spectrum (280 nm to 390 nm) that reaches the surface of the earth is further divided into UVB (280 nm to 315 nm), and UVA (315 nm to 390 nm). When the earth tilts toward the sun, and, as a result, the days become longer, much more UVB reaches the earth’s surface; hence, people experience a lot more sunburns, or more severe sunburns during that time of the year.
1,000 times more UVA reaches the earth’s surface than UVB. UVB exposure is much more conducive to sunburns than UVA. UVB is what our skin cells require to produce vitamin D. Tanning beds emit UVA. UVB rays around 311 nm were found to be quite efficacious in clearing immune-cell mediated inflammatory skin conditions, such as psoriasis, eczema, and even vitiligo. Narrow band UVB rays do not induce as severe of sunburn reaction as in patients who are treated with what is now called broad band UVB, the entire spectrum of UVB, (280 mm to 315 nm). Narrow band UVB treatment has not been found to increase the incidence of skin cancer.
At Brentwood Dermatology we offer narrow band UVB treatments. Patients usually require three treatments per week for the first few weeks. Each treatment takes one to three minutes of exposure in the ultraviolet-light booth. Patients walk in at their own convenient time during the business hours.