Laser hair removal works on the principle of selective photothermolysis, in which melanin from each follicular unit is targeted for thermal injury by laser light. To do this successfully, however, a powerful enough laser must be capable of heating this target without harming surrounding skin cells.
An exhaustive 12-month study demonstrated that both alexandrite and diode lasers produced effective long-term results when patients received four treatments sessions over 12 months.
Fluence
Fluence (joules per square centimeter) of laser hair removal treatments determines both their level of energy delivered to the skin and effectiveness; as its fluence increases, more energy will be delivered more rapidly, leading to quicker treatment timeframes and reduced treatment duration.
Pulse width refers to the amount of time it takes for light energy to reach its full intensity in a target area and plays an integral part in producing results without side effects. Pulse duration must be long enough for epidermal melanin to diffuse heat away from laser exposure while keeping adequate energy available for hair follicle destruction.
Size matters when considering energy levels and side effects of laser hair removal treatments. A larger spot size means deeper laser energy penetration into skin for targeting hair follicles while when the spot size decreases it reverses this effect.
Low fluence settings with large spot sizes generally prove more successful in treating darker skin tones than higher fluence settings, due to less frequent anagen phase hair follicle activation on darker complexions than lighter ones, and their melanin content making their more vulnerable to laser treatment damage.
Professional judgment should be applied when choosing the fluence and pulse width to adjust for individual client reactions in order to achieve the desired cosmetic result and prevent side effects such as blistering or other unwanted symptoms.
However, the operator’s experience and skill are of utmost importance; therefore, it’s recommended that you seek out a trained and licensed practitioner to perform laser treatments; this way you’re ensured of receiving optimal results with minimum risk. When shopping for at-home devices to remove hair yourself, always look out for their joule rating; higher numbers indicate greater power that will remove more unwanted hair on more skin types.
Pulse Width
There are various scientific factors that determine the success of laser hair removal, including wavelength, pulse width and spot size. But ultimately it’s up to technicians’ professional judgement and experience to select the optimal combination for each patient based on many variables such as wavelength, pulse width and pulse duration – these all play an integral part in whether hair follicles will be destroyed during treatment and how quickly.
Laser pulse length is usually determined by the energy produced by a machine and ranges anywhere from nanoseconds to over 100 milliseconds, depending on type and power output of laser used. Within this short duration, it emits a burst of energy that damages hair follicles to disable their future hair production; skilled laser technicians can adjust pulse width according to different depths, skin types and patient comfort when treating hair follicles.
Some follicles deep within the dermis require longer pulse durations for proper heating, helping reduce thermal damage to the epidermis and thus avoid complications such as inflammation and scarring. On the other hand, superficial follicles typically only need seconds of energy for destruction.
As well as altering pulse width, it is also vital for laser technicians to use skin cooling during treatment sessions. This may occur either prior, during, or post laser pulse and can help protect skin from potential damage while optimizing clinical hair removal results.
Thanks to technological advances in lasers, more people than ever before are enjoying the advantages of laser hair removal. This is especially true for patients with darker skin tones or tans who previously could not benefit due to limited options available. Today’s leading developments in laser hair removal have reduced post-treatment regrowth rates up to 95% while providing far superior results than traditional methods. Utilizing adjusted fluences, pulse widths and spot sizes, experienced laser operators can treat patients regardless of skin color or thickness with confidence.
Spot Size
Laser beams penetrate skin, targeting hair follicles with penetrating energy that heats them to break apart the hair follicle and prevent further growth. Lasers come equipped with various spot sizes; which ultimately determine how effective treatments will be.
A larger spot size allows more laser energy to reach its target, increasing thermal damage depth within the follicle and potentially leading to post-treatment skin discoloration risks. Conversely, smaller spots reduce energy delivered directly onto epidermis for post-treatment skin discoloration reduction.
MeDioStar system supports multiple interchangeable handpieces with spots ranging from 1 cm2 to 10 cm2, so it can accommodate a range of skin types. Its versatile spot size ensures safe, effective, and comfortable treatments.
Studies have demonstrated that smaller spot sizes require higher fluences to effectively target the dermis as they tend to reflect or scatter laser energy more. On the contrary, research indicates that larger spot sizes may achieve the same result with lower fluences by allowing more of its energy reach its intended destination.
Pulse duration, the amount of time between when laser energy leaves its tip and hits its target, is also key to effective treatment. It should be shorter than the epidermis’ thermal relaxation time (typically 10 to 100 milliseconds), to allow its epidermis to remain cool against heating from target skin while simultaneously cooling from surrounding tissue.
Researchers conducted a study and discovered that 12 J large spot size treatments achieved comparable results to 25-30 J small spot size treatments after five treatments in type IV skin. While multiple factors contributed to this result, researchers believed larger spot sizes and their ability to deliver more energy directly to targets were major contributors.
Side Effects
Laser hair removal is an efficient, long-term hair reduction method. Based on selective photothermolysis technology, this treatment method targets hair follicle tissue only – permanently damaging it without harming surrounding skin follicles or surrounding tissue – leading to permanent destruction and subsequent inability for new hair growth. Treatment time typically ranges from less than a minute for smaller areas like upper lips up to an hour for larger ones like backs or legs requiring several treatment sessions for optimal results.
To maximize efficacy with minimal side effects in patients with darker Fitzpatrick skin types, it is necessary to assess and select an individual patient-specific optimal level of energy required to destroy hair follicles. This requires not only an analysis of fluence but also of pulse width and spot size parameters. Determining these parameters allows a physician to provide high levels of efficacy while still managing side effects effectively.
When using higher fluences to treat darker skin, thermal damage to the dermis may result in addition to intended destruction of hair follicles, leading to discoloration and scarring in surrounding tissue. Lower fluences could mitigate these problems while providing greater comfort for this patient population.
Studies have demonstrated that laser fluences at lower fluences can effectively control hair growth. One pilot study tested four fluence levels (5, 10, 15 and 20 J/cm2) with a 9mm spot size alexandrite laser on 14 patients who received five axillary treatments each; hair reduction results were comparable with high-fluence treatments.
Laser hair removal works by using heat from a laser beam to penetrate tissue and destroy pigmented hair follicles, with darker pigment absorbing more heat, so darker hairs can be effectively targeted with equal energy level as lighter skin. Follicles must be in their anagen (growing) phase to respond to laser energy; hence most patients require multiple sessions. Although rare, laser hair removal may cause serious complications if performed improperly or exposed too soon to sunlight after treatment.
