study non ablative rejuvenation

8/3/2019 Study Non Ablative Rejuvenation

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Near Infrared Pulsed Light for Noninvasive Skin Tightening,

Toning and Improvement in Texture

Ilan Karavani, M.D. Dermatologic and Cosmetic Surgeon, Antwerp, Belgium

ABSTRACT

The unprecedented demand for skin rejuvenation treatments in recent years has led to the development of many techniquesand technologies aimed at treating age-related skin imperfections. When performing non-ablative skin remodeling with near

infrared lasers (1320nm and 1450nm), the dermis is selectively effected by two basic mechanisms 1) the targeting of

discrete chromophores in the dermis or at the dermal-epidermal junction, or (2 the use of near-to-mid infrared wavelengths,where absorption of water is weak enough that relatively deep beam penetration is attainable. These near infrared lasers

require active cooling means. However, because of their relatively high water absorption and limited penetration, dermal

heating is ineffective with most near infrared lasers. Due to the risks involved, slow coverage rate and cost effectiveness, the

need for new technologies for non-ablative skin tightening procedures has been increasing. The new ST (Skin Tightening)

module for the Harmony platform by Alma Lasers Ltd. (Caesarea, Israel) represents a novel approach in the field of non-

ablative skin rejuvenation. The ST pulsed light technology operates in the near infrared (780-1000nm) wavelength rangewhich allows both deep penetration and effective subdermal heating without the need for aggressive cooling. The ST

handpiece is indicated for the treatment of lax skin and non-ablative skin tightening and remodeling procedures in the facialarea.

INTRODUCTION

The unprecedented demand for skin rejuvenationtreatments has led to the development of many

techniques and technologies aimed at treating age-related

skin imperfections. It can be claimed that the growing

demand for less invasive procedures with short

recuperation time or minimal downtime has paved theway for non-ablative techniques.1

Non-ablative skin rejuvenation encompasses a spectrumof noninvasive techniques where laser, pulsed light or

radiofrequency technologies are used to induce

controlled thermal heating to the dermis while at thesame time protecting the epidermis with cooling. To

achieve subdermal heating a host of infrared laser

devices that target water such as 1320nm and 1450nmlong pulse neodymium:yttrium-aluminum-garnet

(Nd:YAG) have been introduced and used to accomplish

noninvasive dermal heating via nonspecific heating.

However, because of the relatively high water absorption

with these lasers, combined with limited dermal penetration, deep dermal heating was found to be

ineffective. Similarly, with pulsed light technologies inwavelengths between 1100-1800nm (where water

absorption is relatively high), subdermal heating is doneindirectly - partially by direct heating (epidermal) and

partially by heat conduction (subdermal), a technique that

requires aggressive epidermal cooling. It is worth noting

that despite achieving appreciable clinical results,ablative lasers (Er:YAG, CO2) are not used for subdermal

heating since most of the optical energy is absorbed

strongly in the epidermis (which ablates the epidermis).2

The new ST (Skin Tightening) module for the Harmony platform by Alma Laser Ltd. (Caesarea, Israel) is an

innovative (non-laser), pulsed light source in the near

infrared spectrum indicated for deep dermal heating and

non-ablative skin tightening and remodeling procedures.

ST MODULE OVERVIEW

The ST handpiece 780-1000nm (near infrared) has an

ideal tissue optical window for the subdermal heating

(connective tissue, proteins) and low water absorption inthe epidermis. These conditions eliminate the need for

aggressive epidermal cooling. The ST handpiece energyoutput can be set between 5 - 105 J/cm2 based on 3

different selectable time intervals: 5, 10 or 15 seconds.

During each time interval, the repetition rate is kept at3Hz. The large spot size (6.4cm2) allows large coverage

and true investment of energy density for better

penetration and predictable thermal effect. The handpieceis applied on the skin where it is kept stationary for the

entire exposure time (5, 10, or 15 sec) and fluence

conditions. The ST module joins the Harmony systems

existing range of other pulsed light and laser modules.

(A) (B)

Fig. 1: The ST (Skin Tightening) Handpiece and the

Harmony System.


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DEEPDERMAL HEATING

In the aesthetic arena, dermal heating can be achievedindirectly via a process referred to as non-ablative skin

remodeling. In non-ablative skin remodeling, the dermiscan be selectively affected by two basic mechanisms: bytargeting discrete chromophores in the dermis or at the

dermal-epidermal junction, or by using near-to-mid

infrared wavelengths, where absorption of water is weakenough that relatively deep penetration is achievable.

Key components to non-ablative skin remodeling are

epidermal protection and proper selection of laser/light

irradiation wavelength and energy to evoke the desired

thermal response in the papillary and upper reticulardermis. These non-ablative modalities obviate the need

for epidermal injury and promote the reorganization and

prolifiration of important dermal structures to reversephotodamaged and lax skin via thermal or photochemical

process. Heat is generated within the zone of optical

penetration by direct absorption of optical energy. The

heating decreases with tissue depth as absorption andscattering attenuate the incident beam.

The 780-1000nm optical window of the ST handpiece

allows deep penetration (~2.5mm) and deep dermal

heating due to heat conduction and to low melanin and

water absorption in the epidermal-dermal layers. Thefavorable penetration between 780-1000nm wavelengths

means less dermal scattering and more effective heating.

In contrast, the 1100-1800nm optical window used byothers has less penetration (~1.0mm) and more water

absorption, which means greater epidermal heating, and

less dermal heating, a condition which necessitates theneed for active cooling.

Fig, 2 The optical penetration depth of light into the skinin the wavelength range from 400-2000nm (ref. 3)

(Note the relatively deeper penetration of the 780-100nm

wavelengths).

MECHANISM OF ACTION: ST HANDPIECE

Skin remodeling is a biophysical phenomenon that

occurs at cellular and molecular levels via the

intervention of optical or thermal energy. The ST

handpiece exerts its biological effect on the skin throughtwo major mechanisms: 1) heat-induced collagen

shrinkage and micro-thermal injury and; 2) dermalregeneration, repair (wound healing) and remodeling.Collagen cleavage in tissue is a probability event

dependant on temperature. The in-vitro thermal cleavage

of the hydrogen bond cross-links of tropocollagen canresult in the molecular contraction of the triple helix up

to one third of its original length. Cellular contraction

involves the initiation of an inflammatory/wound healing

sequence that is perpetuated over several weeks.

Contraction of skin is achieved through fibroblasticmultiplication and contraction with the deposition of a

static supporting matrix of nascent scar collagen. This

cellular contraction process is a biological thresholdevent initiated by the degranulation of the mast cell that

releases histamine. This histamine release initiates the

inflammatory wound healing sequence. Following

cellular contraction, collagen is laid down as a staticsupporting matrix in the tightened soft tissue structure.

The deposition and subsequent remodeling of this

nascent scar matrix provides the means to alter the

consistency and geometry of soft tissue for aesthetic

purposes. 4-6

TREATMENT PROTOCOL

The ST handpiece is applied on the skin in a stationarymode. The practitioner places the handpiece on the skin

for the entire exposure time and fluence conditions. To

activate the handpiece, the operator should position thehandpiece on the area to be treated and press the

footswitch for the entire selected time interval. Thehandpiece will stop emitting light automatically unless

interrupted by the operator (released footswitch). In order

to continue, the footswitch must be re-pressed.Reposition the treatment head adjacent to treated area.

An average of three non-sequential passes is given to a

specific treatment area.Skin tightening patient candidates are typically younger

patients who are not ready for surgery or are not surgical

candidates. In addition, they may be older patients withmild to moderate laxity who do not want or are not

candidates for surgery. The typical skin tightening,toning and texture smoothing patient does not want the

expanse of surgical intervention or can not afford thedowntime associated with surgery. Both the practitioner

and the patient should identify and agree on the area to

be treated. Marking the area may simplify the treatment

process. Photography is recommended before and afterthe treatment to document the changes. Before initiating

treatment, a Skin Test (single pass) on the intended

treatment area should be done. After covering the area

with thin (


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exposure conditions provided by the manufacturer. The

Skin Test provides the patient and the practitionerfeedback with the level of heat and the patients tolerance

at given time exposure and fluence conditions. Thepatient should be able to tolerate the treatment with nomore than moderate level of discomfort. The initial

treatment conditions should be one that is well tolerated

by the patient and will induce detectable thermal effecton the skin.

During the treatment, the practitioner should monitor

skin temperature using a laser thermometer until the end-

point of 39 - 42C epidermal temperature is reached (Fig

4). Sensitivity to the heat is a determining factor to stoptreating at that level of treatment. Degree of discomfort is

typically from none to mild to moderate. If the patient

does not experience the sensation of heat or does notindicate that the temperature of the tissue is getting

warmer, only up to 3 passes should be used as the

maximum per treatment session.

Fig. 4 Monitoring the epidermal temperature at the

treatment area

Before treatment, the treatment area should be cleaned to

remove perfume, cosmetics and sunscreens. Any jewelry

at the treatment area should be removed. In areas where

hair exists, the hair must be shaved/trimmed. As in any

other light-based procedure, appropriate eye protection(OD>5) goggles must be used by the patient and the

medical staff. For better skin protection, apply a thin

layer (


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Treatment protocol:First treatment: 7-11-05 5sec/15J/cm2/ no cooling;

Second treatment : 7-25-05 5sec/35Jcm

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/ Zimmer on 3Treatment interval: 2 weeks

Before

Deduction from the above computerized analysis of themicrostructure and the comparison of the figures before

and after the treatment led to following observations:

The rose of distribution shows a narrower alignmenttowards the main crease around 160 - 340, indicating

the disappearance of the side branches after the

treatment. The total length of the creases has diminishedfrom 7.39 mm/mm to 6.75mm/mm (decrease of 10%),

reducing the total creased surface by 4% The overalllighter color as seen by the RGB color code indicates a

better reflection of the light due to a finer microstructure.

The strongest indicators are the Maximum Profile PeakHeight (Rp) (reduced from 84.7 GL to 59.74 GL), the

Maximum Height (Rt) (reduced from 115.2 GL to 94.84

GL) and the Mean Spacing of Irregularities (Sm)(increased from 78.63m to 111.91 m). In conclusion,images and data analysis of the skin microstructures with

the SkinEvidence Visio, support to the efficacy of the SThandpiece.

SUMMARY

The ST (Skin Tightening) handpiece is one of the

Harmony platforms 10 different light and laser hand-

pieces. In order to improve and widen clinical outcome

for patients with age-related skin imperfections, the SThandpiece can be used synergistically with the 570nm

(yellow-coded) AFT handpiece. Such combination

therapy is recommended on the face and neck either

before or after the ST treatment. The parameters of theAFT handpiece should be verified through a patch test

just prior to full treatment. The ST module of the

Harmony system for deep dermal heating allows even,

uniform and predictable heating. Uniform heatingreduces the chance of complications. Selecting optical

power is straightforward and it is readily apparent on theHarmony systems user interface how much

.

After

energy is being delivered. No single-use disposables are

needed.

REFERENCES

1. Kim KH and Geronemus RG. Nonablative laser andlight therapies for skin rejuvenation. Arch Facial Plast

Surg 2004;6:398-409.

2. Hardaway CA and Ross EV. Nonablative laser skin

remodeling. Dermatologic Clinics. 2002;20:97-111.

3. Bashkatov AN et al. Optical properties of human skin,subcutaneous and mucous tissues in the wavelength

range from 400 to 2000nm. J. Phys D: Appl Phys

2005;38:2543-2555.4. Arnoczky SP and Aksan A. Thermal modification of

connective tissues: basic science considerations and

clinical implications. J Am Acad Orthop Surg2000;8:305-313.

5. Nelson SJ. Majaron B, Kelly KM. What is nonablative photorejuvenation of human skin? Seminars Cutaneous

Med and Surg 2002;4:238-250.6. Lawrence WT. Physiology of the acute wound. Clinics

Plast Surg 1998;25:321-337.

study non ablative rejuvenation

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