Laser Hair Removal: Strategies, Types and Uses

Test patch: [10, 19]

A test patch is performed by many physicians before performing the actual fist sitting of the procedure. A test patch is usually done on two or three different spots using different parameters. This helps in physician’s evaluation of the ideal treatment parameters and pain threshold for an individual case and also gives an idea to the patient about the procedure and the associated discomfort. This helps in reassuring the patient about the procedure. The patient is called after 72-96 hrs to assess the development of any delayed adverse effects and if there is no adverse sequel, the procedure can be started immediately. The energy density that is required in the first sitting is the one that caused a perifollicuar erythema and edema in the test spot.[ 30] However, a test patch may not always be feasible and is as such not recommended in all cases. It may be considered important in difficult to treat areas and in patients who are apprehensive.

Laser safety

It is paramount to observe safety precautions in all cases. This includes laser safety precautions and personnel safety precautions. These have been listed in box 3

Box3: Laser Safety Guidelines [19]

Treatment Protocol [19,21]

Pat should be asked to wash the treatment area with soap and water to remove any grease, dust or make up. Pre treatment photograph should be taken. The area to be lased should be marked with a white skin marking pencil. [Figure 38.8] Topical anaesthesia or ice cubes can be used to make the patient more comfortable during the procedure especially, if the patient is apprehensive or experienced pain during the test patch. The hair on the treatment area should be trimmed to the skin with the help of an electric trimmer or shaved with a disposable laser just prior to the procedure. The residual hair growth should not be more than 1mm -3mm. If the hair is stuck on the skin surface after shaving, these can be removed with the help of a micropore tape. The exact parameters to be used should be determined based on the test patch result or on basis of the skin and hair type of the patient. Prior to starting the procedure, it is important to recheck the parameters fed in to the system. Make a final check on the safety measures prior to starting the procedure as mentioned in box 3. It is especially important to confirm that all personnel in the treatment zone are wearing safety goggles. The patient should be informed before firing the laser. The hand piece should be kept perpendicular to the skin surface with firm but gentle pressure and there should be complete contact of the hand piece with skin. In case of areas such the mandibular edge, where complete contact in not possible the skin should be pulled towards the flat surface, e.g. cheek, to effect a complete contact. The pressure should be enough to reduce the capillary blood flow and push the hair follicles towards the skin surface. All areas should be treated in a single sitting. The complete area should be covered by proper placing of the handpeice with not more than 10% overlap of the treatment area. Care should be taken that the same area is not lased more than once which can lead to development of adverse effects. Care should also be taken to lase the entire treatment area and not leave behind untreated spots . This can lead to development of patchy hair growth. A treatment grid may be used to prevent these errors. Adequate cooling during the procedures can be achieved by using cool air sources or immediate application of ice packs on the treated area by an assistant. The recent equipments come equipped with cryosprays or precooled sapphire tips for intraprocedure cooling. Development of dusky discolouration or blister formation indicates incorrect parameters and these should be immediately rectified or the procedure should be stopped. Certain difficult to treat areas require special care. These are mentioned in box 4. After completing the procedure the patient should be asked to apply ice packs to reduce pain and edema. At the end of procedure a sunblock cream is applied on the treated area. The procedure details should be immediately noted and this should include the patient details and skin and hair type, procedure details including date/ time, photograph record, fluence, pulse width and cooling method used and lastly the record of any untoward incident should be noted.

Post procedure care at home should be explained and this should include avoidance of heat or hot water bags on the area for at least 24-48 hours, using mild soap and pat drying the treated area and in case if there is a blister formation or any other adverse effect, patient should be advised to apply an antibiotic ointment and inform the treating physician.

Box 4: Laser hair removal in difficult to treat areas

Adverse effects with Laser hair removal [30]

Most complications are mild and transient such as pain erythema and edema. Sometimes superficial thermal burns may be seen. [Figure 38.9 and 38.10] These are generally caused due to wrong parameter settings, physician error during procedures, lack of adequate safety measures and inadequate sun protection by the patient. Table 6 lists the complications during a laser hair removal procedure and its management. Apart from these certain uncommon adverse effects are possible which the clinician should be aware of. Paradoxical hair growth is seen in 0.6% to 10% of patients treated as per data available from different studies. [30]. The possible etiology is the stimulation of vellus hair to form terminal hairs by the low fluences in the areas near to the treatment zones. Another theory is the synchronisation of the hair growth cycle to form terminal anagen hair from the dormant hair follicles. [ 57] Darker skin types [III-VI skin types] and patients with Hirsutism seem to be more prone to develop paradoxical hair growth. Continued laser treatment of the affected area is the treatment for the paradoxical hair growth. Persistent severe urticaria has been reported in a number of patients after laser epilation. Some authors believe it to be due to the delayed hypersensitivity reaction to the ruptured hair follicular antigen. [58]. Nd: YAG Laser treatment of axillary hair has been reported to cause persistent hyperhidrosis. This is possibly due to the stimulatory effect of laser on the hair follicle. [59]. Premature hair greying and ingrowing hair are some other complications reported. [30]

Table 6: complications and its management during laser removal

What’s New in Laser Hair removal?

Newer devices are focussing on faster treatments with better patient experience. Devices with pneumatic skin flattening (PSF) help in reducing pain by working on the ‘gate theory’ of pain reduction. This theory states that on stimulation of the non-nociceptive nerves, signal transmission of pain is reduced. The device suction in the skin that has to be treated and this suction pressure on the skin stimulates the tactile nerve endings that reduces pain sensation transmission. This also helps in bringing the target chromophore closer to the laser window and reduces capillary flow which helps in optimising the treatment as has been explained above [illustration 38.4]. [30] SHR™ technology is another improvement that uses low fluence with rapidly delivered pulses (5-10Hz) and higher average energy. This necessitates the use of multiple passes to build the necessary energy but is faster and has a better patient experience. Another development for performing rapid treatments is computer controlled laser scanner mirrors. These help in automatically placing the laser beam in a perfect non-sequential pattern over a larger skin area. [60]. The technology helps in treating larger areas of various sizes by automatically addressing the issues of correct beam placement.

Miscellaneous pearls in laser hair removal procedure

The procedure of laser hair removal can be optimised by matching the patient and his correct parameters. Table 7 describes the ideal parameters for various skin and hair types

Table 7: Laser parameters based on skin and hair characteristics

As the hair structure changes from thick terminal hair to thin vellus hair, the laser parameters need to be changed to a smaller spot size. Hence a different laser may be needed as the therapy proceeds. Concurrent use of multiple laser wavelengths could have a synergistic effect and this needs to be probed further. Treatment grids are very helpful to prevent skip areas especially when a large area needs to be lased. Some patients may not respond to the therapy. In these cases, changing the wavelength may be helpful.

Conclusion

Laser hair removal remains one of the most commonly availed laser populations. The results post therapy are very gratifying. The learning curve with lasers for hair removal is not as steep as with some other indications. It is important not to be very aggressive, since that can lead to adverse effects. Newer technologies minimize pain and the treatment duration time. Home hair removal systems may prove to be a an essential aid in every house hold in the near future especially since the price are reducing and the newer technologies have made these equipments significantly effective. It is important to keep a standard operating protocol and following it diligently to reduce iatrogenic complications.

Summary

Hair has a lot of aesthetic value irrespective of age and gender. There is a decreased quality of life in hirsute patients. The laser equipments work in the wavelength range of 600-1100nm. Lasers act through the principle of selective photothermolysis and target the melanin but hair reduction occurs by the transfer of heat to the stem cells which are located in the bulge and the hair papillae. This works on the extended theory of selective photothermolysis. The parameters that have to be monitored for optimal therapy are the wavelength, fluence and the pulse width. Multiple equipments are available for hair reduction such as diode, alexandrite, Long pulse Nd YAG and IPL Home use laser hair removal devices are now available but are expensive at present. The commonest indication for hair removal is hypertrichosis in a female, however multiple other indications can be corrected by laser hair removal. Patient assessment includes detailed history and examination. An informed consent should be taken prior to the procedure. The actual procedure is nearly the same with all machines with few subtle differences. Most adverse effects are iatrogenic and following a strict protocol helps in ameliorating these complications. Newer technologies are making the procedure faster and pain free.