The basic principle in epilation applications with laser and IPL; selective photothermolysis. Selective photothermolysis; Absorption of the given light energy by the target chromophore, melanin, and converting it to heat, is to try to create permanent damage to the hair stem cells by means of 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 more intense, and less effective in the catagen and telegen phases. But studies on humans; It shows that the effectiveness of laser hair removal 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 epilation 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 amount of melanin contained in the hair follicles in the same area is different, some hair follicles are permanently harvested at the end of the same session, while others have less effect. In another study, it was determined that the hair shaft was destroyed by thermal heat after histopathological and immunohistochemical examinations after laser application, but the immunohistochemical structure of the hair follicle generally remained the same. For this reason, it has been suggested that laser and Ipl systems act not by destroying the hair stem cell, but by causing a change in its functions. As can be seen, extensive research is needed to better understand the physiopathology of hair removal 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 epilation purposes since 1996. The shorter the wavelengths of the devices, the higher the melanin selectivity, that is, the greater the effect. However, since the melanin selectivity is high, it will affect the melanin in the epidermis, so the possibility of burns is higher. In addition, its length determines the depth of penetration. Short wavelengths will remain superficial, while longer wavelengths will penetrate deeper. For these reasons, the short wavelength Ruby laser is no longer used, 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. While some of them find no difference between different laser systems, some find the results of certain wavelengths more successful. In my personal opinion, the gold standard in epilation is the Alexandrite laser. However, in patients with darker skin types and tanned patients, Diode and Nd:YAG lasers with longer wavelengths are safer.
Numerous new trials are being conducted to achieve better results in laser and IPL hair removal. One of them; Q-Switch lasers. These lasers shoot in nanoseconds. Effect mechanisms; Photomechanical damage. In other words, it is tried to explode the follicle with photoacoustic shock waves. Although there are Q-Switch systems at different wavelengths, the most commonly used Q-Switch is the Nd:YAG laser. Although there are studies that give successful results, my clinical observation only provides a slight reduction in very fine hairs as a result of long sessions. However, if it is thought that other devices are not very successful in dark-skinned patients with fine facial hair and may even have paroxymal hypertrichosis, it can be tried even if the results are not good. Other researchers also thought that the results were not so good that they did the following study to increase the photomechanical damage; First, carbon particles with a diameter of 10 micro millimeters are applied to the waxed skin and then shot is made with low energy (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 delaying hair growth, its long-term results have not been good.
Another innovation in devices; Combined devices using two different wavelengths, ie; They are devices that can throw two different wavelengths of light in the same pluse. They are devices that do this both sequentially, that is, by first throwing one wavelength in the same pluse and then the other wavelength when pressing the pulse pedal, and simultaneously, that is, by throwing both wavelengths together at each pedal press. 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. My personal observation is that although the results do not change 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 are very concentrated around the hair and heat this area very 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 good results. My personal observation of the results is that radiofrequency does not provide a huge increase in the result, but it causes an increase in the complication rate.
Of the defeats in laser and ipl devices, what excites me the most is Robot lasers. These are computerized systems that enable the selected area to receive homogeneous and sufficient energy by controlling the data simultaneously with a high-resolution webcam, temperature and distance sensor, and a computer interface. 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 shown that the addition of laser treatments increases the success of the treatment. The cream, which is not available in Turkey, is sold abroad under the name Vagina, unfortunately it is expensive.
Except this; In a study in which melanin-containing liposomal capsules called Lipoxome were used topically to enrich the region with melanin with melanin solutions, a statistically significant difference was found between the areas where melanin was applied and the areas where melanin was not applied.
When it comes to innovations in laser and IPL hair removal, it is necessary to talk about laser and IPL devices produced for home. They are low-power devices currently being produced at IPL and Diode laser wavelengths. Although there are many studies that find household appliances effective, it is not possible to achieve permanent hair reduction with such low-power energy producing devices. Although the measurements are considered safe for the eye due to the low dose when used appropriately, 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 doses lower than the effective dose increases especially fine hairs. There are publications about the increase of hair in people who already epilate with home appliances. In my opinion, many people who buy these devices, which are not cheap at all, will complain to us, the dermatologists, because they have hair growth.
Dr. Fatma Yildiz