The basic principle in epilation applications with laser and IPL; selective photothermolysis. Selective photothermolysis; The purpose of the light power given is to be absorbed by melanin, which is the chromophore, and to convert it into heat, to try to create permanent damage to the hair stem cells thanks to this heat. Hair stem cells that are tried to be destroyed; They are non-pigmented cells located in the deep part of the hair follicle and in the outer root sheath, close to the erector pili protrusion, that enable the hair shaft to be produced.
Animal experiments; He found that the laser beam was more effective in the anagen phase, where the pigment was heavier, and less effective in the catagen and telegen phases. However, studies on human beings; It shows that laser epilation activity is not always related to the hair growth cycle. The reason for this is that it is thought that there is enough melanin in the human hair follicle to absorb the light in each phase. It has been shown that the heat generated by the light sources used for hair removal is effective in destroying hair by damaging the vascular structure in the peribulbar area, as well as the hair stem cells. However, in practice; Since the melanin content of the hair follicles in the same area is different, some hair follicles are permanently fixed at the end of the session, while others have less effect. In another study, after histopathological and immunohistochemical examinations after laser application, it was found that the hair shaft was destroyed by thermal heat, but the immunohistochemical structure of the hair follicle remained the same. For this reason, it has been suggested that laser and Ipl systems affect the hair stem cell, not by destroying it, but by causing a change in its functions. As can be seen, there is a need for extensive research in order to better understand the physiopathology of the epilation process performed with laser and IPL systems.
It is clear that the defeats are mostly in laser and IPL devices. Ruby Laser (694nm), Aleksandrite Laser(755nm), Diode Laser (800-810nm), Nd:YAG Laser(1064nm), IPL (Intense Pulse Light)(590-1200nm) devices have been used for hair removal target since 1996. The shorter the wavelengths of the devices, the higher the melanin selectivity, that is, the more it affects. However, since the melanin selectivity is high, it will affect the melanin in the epidermis, so the possibility of burns is higher. Moreover, its length determines the depth of penetration. Short wavelengths will remain superficial, while longer wavelengths will penetrate deeper. For these reasons, Ruby laser with a short wavelength is not used anymore, although it is the first laser used because it has a high effect on melanin in the epidermis and remains very superficial.
There are many studies comparing results with lasers of other wavelengths. Some of them find no difference in the middle of different laser systems, while others find the results of reasonable wavelengths more successful. In my personal opinion, the gold standard in epilation is the Alexandrite laser. However, in patients with darker skin type and tanned patients, Diode and Nd:YAG lasers with longer wavelengths are more reliable.
Numerous new trials are being carried out in order to obtain more accurate results in laser and IPL hair removal. One of them; Q-Switch lasers. These lasers shoot in nanoseconds. Effect systems; Photomechanical damage. In other words, it is tried to explode the follicle with photoacoustic shock waves. Although there are Q-Switch systems with different wavelengths, the most commonly used Q-Switch is the Nd:YAG laser. Although there are studies that give successful results, my clinical observation, however, provides very little reduction in very thin hairs as a result of long sessions. On the other hand, if it is considered that other devices are not very successful in dark-haired patients with fine facial hair, and even paroxymal hypertrichosis may be present, the results can be tried even if it is not good. Other researchers also thought that the results were not very sufficient, so they did the following study in order to increase the photomechanical damage; First, carbon particles with a diameter of 10 micro millimeters are applied to the waxed skin and then shot with low power (2-3 j/cm2 Q-switched Nd: YAG laser 1064nm, 10 Hz, 10 ns pulse duration, 7 mm spot size). With photoacoustic shock waves, it is aimed to explode carbon particles and damage the follicle. Although it is very effective in retarding the growth of hairs, its long-term results have not been found to be good.
Another innovation in devices; Combined devices using two different wavelengths, ie; They are devices that can throw two different wavelength beams in the same pluse. They are devices that work both sequentially, that is, by throwing one wavelength in pluse and then the other wavelength, simultaneously, that is, by throwing both wavelengths together when pressing each pedal. There are studies that find and do not find a difference between the use of a combined device and the use of a single wavelength. Although my personal observation did not change the results much, the coplication rate increases due to the sum of the coplications of both wavelengths used.
Laser and IPL devices can also be combined with Radiofrequency. Radiofrequency is applied to the tissue together with light. Hair is not radiofrequency conductive or absorbent. RF currents become very heavy around the hair and heat this area too much. The heating provided by the absorption of light is added to this warming and the follicle is coagulated. There are many studies reporting very favorable results. My personal observation of the results is that radiofrequency causes an increase in the complication rate, although the result does not provide a huge plus.
Of the defeats in laser and ipl devices, what excites me the most is Robot lasers. These are computerized systems that provide homogeneous and sufficient power to the selected area by controlling the data simultaneously with a high-resolution webcam, temperature and distance sensor, and the computer midface. Since it measures the temperature on the skin surface instantly, it reduces the possibility of burns.
Other innovations that can be mentioned apart from laser and ipl devices; Eflornithine is cream. This cream is an irreversible blocker of the enzyme Eflornithine ornithine decarboxylase, which leads to the reduction of polymines, which are the building blocks of rapidly dividing tissues. Studies have also shown that adding it to laser treatments increases the success of treatment. The cream, which is not available in Turkey, is sold abroad under the name Vagina, unfortunately it is valuable.
Except this; In a study in which melanin-containing liposomal capsules called Lipoxome were used topically to enrich the area with melanin with melanin solutions, a statistically significant difference was found between the areas with and without melanin applied, but when the additional effort and cost in the application was considered, the result was considered disappointing.
When it comes to innovations in laser and ipl epilation, it is definitely necessary to mention laser and ipl devices produced for residential use. They are low power devices currently being produced at IPL and Diode laser wavelengths. Although there are many studies that find residential devices effective, it is not very possible to achieve permanent hair reduction with devices that produce energy at such low power. When the measurements are used appropriately, even if they find it safe for the eye due to the low dose, incorrect use (shooting too close to the eye) or malfunctions in the device will increase the likelihood of complications. Another problem is paroxymal hypertrichosis. As we know, heating the area at lower doses than the active dose causes an increase in fine hairs. In fact, there are publications that the hairs increase more in individuals who epilate with residential-type devices. In my opinion, many people who buy these devices, which are not cheap at all, will complain to us dermatologists again because they have more hair.
Dr. Fatma Yildiz