▶ Previous Artlcle : #10-1. Development of Hair Removal Lasers II
4. History of LightSheer
I would like to introduce detailed history of LightSheer from my experience of having used 10 LightSheer devices so far. This would be also helpful for understanding the development of other hair removal lasers because they all seem to go through quite similar process as LightSheer.
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The first model of LightSheer was SC, a diode laser with 9×9 mm2squarespotsize,5to30mspulseduration,maximumfluenceof40J/cm², repetition rate of 1 Hz, 800 nm wavelength, and contact cooling system. The next model was EC, which had the same spec other than higher maximum output of 60 J/cm² and repetition rate of 2 Hz. Higher maximum output means better hair removal effect in patients without side effects, and repetition rate of 2 Hz means twice faster procedure time in the same patient.
Clinicians experienced in laser hair removal started to recognize the importance of the actual permanent or long-lasting hair removal effect and procedure time. To meet their needs, LightSheer XC model was released in 2000, with broadened spot size from 9×9 mm2to12×12 mm2andprolongedirradiationtimeto100ms.Thismodelhasbecomeasteadysellerwithoutmuchchangeforalmost13yearsnow,exceptanotherupgradetoincreasethepulsedurationto400ms.Increasingfluence,broadeningspotsize,andraisingthenumberofshotspersecondultimatelymeanproducinganexpensivedevice,whichwillleadtoahighersellingprice.Suchchangeswasquiteaburdenondoctorswhowerepurchasingthesehairremovaldevices.Withhairremovalbecomingmorecommon,clinicsarecompetingwitheachotherbyloweringthepricefortheprocedure,leadingtoreductioninthedemandforexpensivehairremovallasers.Alater,cheapermodels,suchasST(maximumfluence40J/cm², 9×9 mm², 1 Hz) and ET (maximum fluence 100 J/cm², 2 Hz, 9×9 mm²), could be successful in this context. In late 1990s and early 2000s, researchers have turned their attention in the mechanism of hair removal from simple selective destruction of hair follicles to destruction of hair stem cells or papilla cells in the hair roots. Upon this theoretical background, most devices tended to have longer pulse duration since then. This change has been maintained so far merely based on the theoretical background, but not supported by robust evidence; there has been no clinical study which have proved that 100 or 400 ms pulse duration was actually helpful, and nor do I believe that such a change is necessary, except for special cases such as patients with black skin. From mid-2000s, with increasingly more people receiving laser hair removal, more and more people also avoided the procedure for fear of pain. In mid-2000s, I conducted a survey of women in their 20s who have not experienced laser hair removal. Their major concerns about hair removal were the price of procedure and pain. For this reason, less effective, less painful, cheaper lasers have appeared in the market, leaving no choice for the companies but to focus on the sales of LightSheer SC and ET models. In 2008, a new model Duet, with HS handpiece eqipped with photopneumatic system was released. HS handpiece has a 22×35 mm² wide spot size to shorten the procedure time and the photopneumatic system beneficial for decreasing pain. The device was not very popular at the moment due to the high price and the unvalidated efficacy, but recently the number of clinics using this device is increasing.
LIGHTSheer XC.
LIGHTSheer ET.
LIGHTSheer Duet.
5. Long pulse Nd:YAG
Long pulse Nd:YAG has been marketed as hair removal laser since 2000. The representative device in the early period would be Coolglide. Long pulse Nd:YAG laser has been found to be as effective for hair removal as previous diode laser or alexandrite laser, but it is not widely used yet relatively. Clinics are not willing to use it because the light of this laser reaches deep in the skin and affects greatly on blood vessels, which may result in scarring rarely. However, a variety of options in spot size and pulse duration, as well as high fluence, provide an ample choice for clinics active in laser hair removal. In the next article, we will take a look at milestone studies on the clinical efficacy of various hair removal lasers and discuss how doctors have changed their opinion on laser hair removal with time.
<Appendix 1>
Palomar Medical Technologies, Inc. and its hair removal devices
Palomar was established in 1987 to manufacture medical or aesthetic devices using laser or light. The company had more than 10 subsidiaries in 1997. In April of the same year, Epilaser, the first ruby laser for hair removal in the world, was approved by the FDA for hair removal. The company then cleared up the studies on other fields of medical laser and started to focus on dermatological or aesthetic devices using laser or light.
In December 1997 and January 1998, LightSheer, produced by Star medical Technologies, Inc., a subsidiary of the company, was approved by the FDA for hair removal and vascular lesions. In 1999, Coherent acquired Star Medical Technologies, and in 2003, the company made an agreement with Gilette, a famous razor company, to develop an at-home hair removal product for women. With a number of patents in hair removal, Palomar is still receiving royalties from lots of companies or filing lawsuits over royalties. Recently Palomar launched a new long pulse diode hair removal laser, Vectus which have very large spot size(23 x 38 mm²).
<Appendix 2>
Summary of the development process of hair removal laser
Any wavelengths that are relatively well absorbed by melanin, a component of hair, can be used for hair removal laser. Ruby laser of 694 nm was first adopted, but it was difficult to use in people other than Caucasian due to the safety issue and high absorption rate in epidermal melanin. For hair removal in these people, 755-nm alexandrite laser, 800-nm diode laser and 1064-nm Nd:YAG laser were widely used.
Earlier lasers adopted 3-ms pulse duration because the investigators in universities and laser companies focused solely on the hair shaft in those days. With the emergence of hair stem cell as a new target, devices with 30-40 ms, or even 400 ms and up to 1s, has been released. However, their superiority in efficacy has not been proved yet, and 30-40 ms is still accounting for the majortiy.
Skin cooling system is essential for delivering sufficient fluence to hair without causing side effects on the skin surface. For this purpose, dynamic cooling device using cold gas, contact cooling system or cold air has been added or utilized.
Bigger spot size can deliver sufficient energy to a deeper area, which is helpful for improving the effect and reducing procedure time. All companies competitively released lasers with bigger spot sizes in the early days, but not any more for the same models since mid-2000s. This might be because bigger spot size requires higher manufacturing cost and, although it may be more effective, expensive devices is not welcomed in the market anymore. A lot of new devices have been developed rather to reduce the cost, regardless of their effectiveness. Now 18 years since the initiation of hair removal, people are also starting to notice the varied outcomes across clinics, and there is a new growing demand for more effective hair removal laser even at a higher cost.
-To be continued-
