Clinic news

Candela GentleLase Plus VS. Lumenis LightSheer ST, ET & XC Models

*Specifications of LightSheer laser evaluated match both ST & ET models.

FACT:  In laser hair removal, GentleLase represents the optimal combination of wavelength, fluence, spot size, pulse duration and epidermal cooling for the broadest range of patients.

Power, Fluence & Efficacy: GentleLASE lasers dwarf the competition’s peak power numbers, enabling the GentleLASE Plus to deliver not only higher fluences (3), but also higher fluences at shorter pulse durations (4).  GentleLASE lasers can deliver up to 100 J/cm² in a 3 ms pulse width (5).  As you can see below, LightSheers only offer a 5 ms pulse duration, and greatly reduced fluences as pulse durations decrease.  Lasers have to be able to deliver sufficient fluences at shorter pulse durations to remain below the thermal relaxation times* of the smaller diameter hairs and to effectively treat finer, thinner hairs.

See also:  LightSheer Diode Laser Systems User Manual (p. 28)
Candela Technical Update Volume 1 [TRT explanation]

*Thermal Relaxation Time – the time it takes for the target (hair) to dissipate ½ the energy absorbed.  For 95% of follicles in the areas most commonly treated on the body, the optimal ‘TRT’ is 1-5 milliseconds.  For the remaining 5% the TRT extends out to 10ms.  As pulse duration extends past the ‘TRT’ efficacy is reduced.  This is because the follicle is allowed to dissipate the heat faster than it can cause complete thermal heating or damage.

Spot Size, Speed & Patient Comfort: Simple spot size geometry tells you that the larger the spot size, the greater the area treated AND the fewer laser pulses required.  The industry leading 18mm spot size on the GentleLase Plus is more than 3-times larger than the LightSheer’s 9X9 mm spot (7) and, as documented in a side-by-side comparison, more than 3-times faster than the LightSheer.  Ask your patients if they prefer to be treated with a LightSheer laser that requires three times the laser pulses as a GentleLASE Plus to cover the same treatment area (8), especially since it has been reported in Cosmetic Surgery Times that the LightSheer hurts more than the GentleLASE Plus on a per pulse basis?

See also: GentleLASE vs. LightSheer—Time & Motion Analysis Cosmetic Surgery Times, “Anesthesia use requires factoring in laser spot sizes, wavelengths for pain control”

Repetition Rate, Spot Size, Speed & Treatment Efficacy: As you can see, on those models LightSheer claims to have a faster repetition rate than the GentleLASE (to compensate for the LightSheer’s smaller spot sizes), Hz rates decrease dramatically as effective fluence levels are attempted to be delivered.  Additionally, spot size physics states that the larger the spot size, the greater the energy delivered.  Large spot sizes deliver energy deeper into the tissue than small spot sizes.  Not only are larger spot sizes faster, they are more effective as well.

LightSheer ET model

See also: “Comparative Monte Carlo Examination of Energy Penetration for Different Hair Removal Lasers”

“Comparison of the Candela GentleLASE Hair Removal System with other Technologies”

Epidermal Cooling & Ease-of-Use: Candela’s DCD (Dynamic Cooling Device) cryogen spray is the premium cooling system on any laser today.  DCD extracts more heat from the epidermis than by any other means (dropping nominal skin temperature between –40C and –60C PER LASER PULSE).  DCD is the far more consistent cooling methodology--computer controlled & independent of operator experience or technique.

The temperature of the skin with contact cooling will depend on how long the chilled tip remains in the same area.  The faster the operator moves the hand-piece, the less cooling the treatment site will receive.  As consistency becomes compromised, the risk of epidermal injury increases.

LightSheer recommends constant contact with the skin with its contact cooling handpiece - it can be very difficult to see what area has been treated and how fast the treatment should proceed.

See also: “A Comparative Study of Human Skin Thermal Response to
Sapphire Contact and Cryogen Spray Cooling”  LightSheer Diode Laser Systems User Manual

HandPiece Design: By design, Candela’s GentleLASE handpiece is lighter and easier to manipulate than LightSheer’s heavier, pistol-grip designed handpiece.  Repetitive motion trauma is a serious workplace concern, and operator fatigue is greatly minimized with the GentleLASE design versus LightSheer’s handpiece

See also: Ergonomic Analysis of LightSheer vs. GentleLASE Plus Laser
Treatment Devices”

Price: Why pay more for less effective hair removal, more time-consuming hair removal, more painful hair removal and more frequent hair removal?  At $72,500, the higher-powered GentleLASE Plus is much less expensive than all three single-spot LightSheer models, beginning at $75,000 for the ST (9X9 mm spot), $89,000 for the ET (9X9 mm spot) and $129,000 for the XC (12X12 mm spot).

See also: LightSheer Data Sheet

Comparative Study: Sorin Eremia, Cindy Li, Nathan Newman, “Laser Hair Removal with Alexandrite versus Diode Laser Using Four Treatment Sessions: 1-Year Results” Dermatologic Surgery 2001

Lumenis will want to point out that the study concludes "Both the alexandrite and diode lasers in this 12-month study produced excellent long-term hair reductions." 

But that’s not the whole story!

This study was designed to compare hair removal efficacy at "equivalent" laser parameters.  In other words, to match the LightSheer's 9X9 mm spot size and fluence range, the GentleLASE Plus had to be operated using its 12 mm spot size and associated fluence range.  That's like in auto racing, telling one car not to use its fifth gear!  Dr. Eremia points out as much in the study, as he introduces his study with a brief overview of laser physics and the importance of wavelength (melanin absorption), power (more is better), spot size (speed and ease-of-use), pulse width (TRT implications) and skin cooling devices (consistent epidermal protection) in laser performance--all of which provides the basis for the conclusion that the GentleLASE Plus is a superior hair removal laser!

After the Materials & Methods and Results sections of the study, in which similar hair removal results were reported being seen with both lasers using similar settings, Dr Eremia makes the following points in the Discussion section:

Wavelength: Higher melanin absorption at 755 nm than 810 nm--"In theory, lighter hair should do better with 755 nm and worse with 810 nm..."--755 nm beam scatters more than 810 nm at the same spot size, but the GentleLASE has available a much larger spot size than the LightSheer.
Pulse Width: Because of the GentleLASE's 3 ms pulse duration, "we would expect finer, lighter hairs to do better with the alexandrite laser."

Spot Size: "In theory, the larger alexandrite laser spot size should have compensated for beam scatter, delivering roughly the same effective fluence at the target depth of the hair follicle as the smaller 800 nm diode laser spot size..."

Cooling System: "[DCD] provides very consistent skin cooling and is not operator dependent.... Our experience with [contact cooling] seems less efficient, less effective, and significantly more operator dependent than the cryogen spray device."

At similar settings, both the GentleLASE and LightSheer lasers are effective hair removal devices.  But Dr. Eremia clearly prefers the DCD over contact cooling, and he consistently points out that while the LightSheer's capabilities were evaluated at maximum settings, GentleLASE advantages in terms of speed, efficacy and ease-of-use should be obvious when IT'S maximum laser parameters are utilized.

Company & Product track record – The GentleLase Plus has been on the market for 5+years & is regarded as the Gold Standard for laser hair removal.  The LightSheer technology has been sold twice in the last three years.  Three different companies have sold the LightSheer line, who will be next?  Candela, on the other hand, is a 32 year-old publicly held company with a proven track record in manufacturing, sales and service in the laser industry.

You’re not just buying a laser, you are also investing in a company.  Why gamble with patient satisfaction and your maximum revenue potential?  Candela has a 32-year track record of providing the top technologies in the marketplace.  Candela manufactures, sells and services its lasers and has since it was founded. 

CONCLUSION: Melanin absorption, wavelength, epidermal cooling and energy delivery are the key factors in laser hair removal efficacy. The GentleLASE targets far more melanin than the LightSheers.  Dynamic Cooling is more effective and consistent than contact cooling. GentleLase lasers are more powerful and are capable of delivering more energy than the smaller LightSheers.  You are buying a major piece of medical equipment with the GentleLASE Plus.

The complete package is Candela