Intense pulsed light
Intense pulsed light (IPL) is a technology used by cosmetic and medical practitioners to perform various skin treatments for aesthetic and therapeutic purposes, including hair removal, photorejuvenation (e.g. the treatment of skin pigmentation, sun damage, and thread veins) as well as to alleviate dermatologic diseases such as acne.[1][2][3][4][citation needed] IPL is increasingly used in optometry and ophthalmology as well, to treat evaporative dry eye disease due to meibomian gland dysfunction.[5][6][7][8]
The technology uses a high-powered, hand-held, computer-controlled flashgun to deliver an intense, visible, broad-spectrum pulse of light, generally in the visible spectral range of 400 to 1200 nm. Various cutoff filters are commonly used to selectively filter out shorter wavelengths, especially potentially damaging ultra violet light. The resulting light has a spectral range that targets specific structures and chromophores (e.g. melanin in hair, or oxyhemoglobin in blood vessels) that are heated to destruction and reabsorbed by the body. IPL shares some similarities with laser treatments, in that they both use light to heat and destroy their targets. But unlike lasers that use a single wavelength (color) of light which typically matches only one chromophore and hence only treats one condition, IPL uses a broad spectrum that when used with interchangeable filters, allowing it to be used against several conditions. This can be achieved when the IPL technician selects the appropriate filter that matches a specific chromophore.[9]
Efficacy
In August 1997, IPL was reported to have permanently removed terminal hair in two patients who underwent multiple treatments to their beards.[13] In October of that year, the first IPL system developed for hair removal and resulted in 60% hair reduction after 12 weeks.[25]
It is important to note that these studies utilized a variety of IPL devices on patients with various hair types, skin types, and targeted skin areas. Thus the results are not directly comparable.
According to the FDA, permanent hair removal means the "long-term, stable reduction in the number of hairs regrowing after a treatment regime." In other words, the number of hairs regrowing must be consistently greater than the duration of the complete growth cycle of hair follicles, which varies from four to twelve months by body location.[26] IPL has been found to be much less effective than laser hair removal; however, many patients experience satisfaction with significant hair reduction.[23]