CUTANEOUS LASER THERAPY

CUTANEOUS LASER THERAPY

Dr. L.Y. CHONG & Dr. H.H.L. CHAN

CHAPTER 21

1. INTRODUCTION

1.1. Definition

The word laser is the abbreviation of Light Amplification by the Stimulated Emission of Radiation. Laser light is characterised by monochromaticity, spatial coherence and high intensity.

1.2. Applications in Dermatology

Different laser systems, each with its own unique properties, are now used for a wide range of dermatological conditions. These systems are named after the media that are used to produce the laser lights. They include carbon-dioxide, argon, organic dyes, heavy metal vapour, krypton, neodymium-YAG, ruby, and alexandrite lasers. (Table 1) In practice, dermatological applications of laser technology can be divided into three categories:

surgery (cutting, haemostasis) and vaporisation;

selective photothermolysis of superficial vascular disorders;

selective photothermolysis of pigmented lesions and tattoos.

2. LASER BIOPHYSICS

2.1. Joules, Watts, Fluence and Power Density

Radiation energy is measured in Joules (J) and is directly proportional to the quantity of photons of the radiation. The rate of energy exposure is measured in Watts (W) where 1W = 1J/s. The total amount of energy exposed to a surface is known as the fluence (energy density) and is expressed in term of Joules per metre square (J/m²). In laser surgery, fluence determines the total volume of tissue damage. The rate of tissue damage depends on the power density of the laser beam. Power density or irradiance is defined as the rate of energy delivery per unit area (W/cm²). Power density of a laser beam is directly proportional to its output but inversely related to its spot size and can be calculated as follow:

Power density (W/cm²) = Power output (W)/Spot size (cm²)

2.2. Properties of Laser Light

Laser light has the following characteristics:

1. A high degree of monochromaticity: The active medium determines the emission wavelength which is restricted to a very narrow band.
2. A high degree of coherency: This is due to the fact that all light waves are in phase. Laser light is highly directional with a low degree of divergence.
3. High intensity: The amplification process allows the emission of high-energy level laser.

2.3. Laser Beam Modalities

Laser beams can be continuous, pulsed, superpulsed, or Q-switched. Continuous lasers (CW) produce beams with a constant output. The beam can be interrupted by a shutter controlled by the operator, resulting in the production of shuttered continuous wave (mechanical pulse). Pulsed lasers emit beams ‘compressed’ into high intensity pulses. Each pulse last about several hundred microseconds, generating energy 100 times more than that of the CW lasers. Better understanding of the concept of selective photo-thermolysis has resulted in the development of laser systems with very short pulses and high peak power. These are the Q-switched lasers. This refers to the use of techniques such as an electromagnetic switch to stop laser passing through the cavity abruptly. This blockage is then suddenly removed allowing the production of pulses with short duration (in the range of nsec) and high irradiance (1,000,000 W/cm²).

2.4. Laser Delivery Systems

Three systems are currently being used to deliver laser light from the optical cavity to the tissue: articulated arms, fiber optics, and automatic scanning devices.

1) An articulated arm involves the use of rigid tubes with reflective mirrors at each connecting end.

2) Fibreoptics are fibres consisting mainly of quartz and are used to transmit light.

3) Manual control of laser light delivery is subjective and can be inaccurate even in experience hands. Micromanipulator improves the accuracy of laser light delivery and can be connected to the fiber optics or the articulated arm through a microscope. Automatic scanning devices involve the use of computer-controlled micromanipulator that deliver laser light in a controlled manner.

2.5. Skin Optics

The interaction of light radiation with skin is determined by the optical properties of skin constituents and on the wavelength of the incident light. In the epidermis and stratum corneum, radiation with wavelengths below 300 nm is absorbed rather than reflected. Different chromophores will absorb radiation of specific wavelengths. Protein, urocanic acid, melanin and nucleic acid are the main chromophores for radiation in the ultraviolet C and B range (< 320 nm). Melanin also absorbs radiation with wavelengths between the range of 320-1,000 nm. Water is the dominant chromophore for radiation of higher wavelengths (> 1,000 nm). Radiation with wavelengths greater than 300 nm have a greater degree of penetration and can therefore reach the dermis. In the dermis, most of the transmitted radiation is scattered from the collagen bundles back to the environment. Some degree of dermal absorption by chromophores such as haemoglobin and bilirubin do occur. Radiation such as ultraviolet A, blue, green, and yellow light are absorbed by haemoglobin. The term “optical window” refers to the ability of radiation to penetrate deep into skin tissue because of low absorption and low scattering. This applies to radiation with wavelengths between 600-1,300 nm. Melanin is the main chromophore at this spectrum.

2.6. Skin Chromophores and Laser

Using lasers light with wavelengths that match that of the skin chromophores, selective tissue damage can be achieved. Light emitted by the ruby laser (694 nm) or Nd:YAG laser (1,064 nm) can be absorbed by melanin containing cells leading to their destruction. Argon and yellow light lasers are absorbed by haemoglobin and can be used for the treatment of vascular lesions. The carbon dioxide laser has a wavelength of 10,600 nm which is absorbed by water and is therefore nn-selective.

2.7. Types of Interactions Between Laser Light and Skin

Laser, like other electromagnetic radiation, can produce photothermal, photomechanical and photochemical reactions in skin.

Photothermal interactions, are derived directly from heat generated by laser. If skin is heated to temperature just below 50^o C, the consequent thermal tissue damage is still reversible. At higher degrees (50-100^o C), coagulation of protein occurs leading to irreversible thermal damage. At even higher temperature (>100^o C), vaporisation of tissue occurs. This takes place when the water component of the affected tissue reaches its boiling point and vaporised. The type of thermal tissue damage induced (coagulation or vaporisation) depends on the power density, there is, high energy pulses cause tissue to pass its boiling point and produces vaporisation. The extent of thermal damage is directly proportional to the amount of heat dissipated from the target site to the surrounding tissue. Heat requires time to diffuse outward and cause thermal damage. The extent of thermal damage, therefore, depends upon the rate of heating which is determined by power density and exposure time. If the exposure time is shorter than the target’s thermal relaxation time (defined as the time required for a target to cool from the temperature achieved immediately after laser irradiation to half that temperature), heat will not be able to diffuse out. This allows the thermal damage to be limited to the target site. Selective tissue damage restricted to the target site can be achieved using a laser with a wavelength that is specifically absorbed by the target tissue, where it is converted to heat resulting in a thermal injury. This is referred to as Selective photothermolysis. As the thermal relaxation time of an object is inversely related to its size, lasers with ultra-short pulses emitting high energy have been developed. In photomechanical interactions, high energy-level pulse laser disperses the target tissue by rapid thermal expansion and local vaporisation. A good example of this reaction is the use of Q-switched ruby laser in the removal of tattoo. High energy impulses from the laser disperses the ink particles and the dermal macrophages that contain them. The main role of laser induced photochemistry is photodynamic therapy for the treatment of cancer. This involves the use of laser, in conjunction with a topical or systemic photosensitizer, in producing the beneficial effects.

In summary, the principle of laser therapy is to emit a specific wavelength of photon energy is to the target tissue, aiming to have optimal absorption of energy by the target tissue, while minimizing the destruction of the surrounding normal tissue. Three basic elements have to be considered: Firstly, a specific wavelength that is optimally absorbed by the target structure (depending on absorption curve of the chromophore); secondly, an exposure duration less than the time necessary for cooling of the target structure (using pulsed or Q-switched mode); and thirdly, sufficient energy fluence must be delivered to reach a destructive temperature in the target.
 

3. CLINICAL APPLICATION OF SPECIFIC LASER SYSTEMS

3.1. Carbon Dioxide (CO2) laser: Surgery and Vaporisation

The CO₂ laser has a wavelength of 10,600 nm (i.e. within the invisible infrared spectrum). It is used in conjunction with a coaxial helium-neon laser beam which is visible and acts as a guide light.

Water is the main chromophone of CO₂ lasers. Ninety percent of the skin is made up of water and the effect of the CO₂ laser is therefore non-specific. CO₂ lasers can be operated either as a cutting tool [“light knife”] or as an ablation tool [“laserbrasion”]. As mentioned above, the rate of thermal damage is related to the power density (which is inversely proportional to the spot size for any given energy.) For CO₂ lasers to act as a cutting tool, high power density leading to instant and precise tissue vaporisation is necessary. To achieve this, the CO₂ laser is placed close to the tissue surface (generally, less than 1 inch) so that the beam is focused (0.1-0.2 mm in diameter) and has a high power intensity (50,000-75,000 W/cm²). As the beam incises tissue, It will also seal blood vessels and lymphatics, allowing control of haemostasis. This makes it useful for patients with bleeding disorders or patients in whom adrenaline is contraindicated. It is also useful in patients with pacemakers in whom electrosurgery is contraindicated. Furthermore, because of its ability to seal nerve endings, patients tend to suffer less postoperative pain. The CO₂ laser sterilises at the same time and is also useful for the debridement of infected ulcers or burns.

The CO₂ laser may also be used to vaporise tissue by positioning the laser further away from the skin surface than for cutting so that the beam is defocused (1-2 mm in diameter) and the power density low (150-500 W/cm²). The power density is adjusted so that it is low enough to achieve rapid complete tissue vaporisation without charring. Many applications for CO₂ laser vaporisation have been reported. (Table 2) However, with advances in technology, newer laser systems have proved to be superior to the CO₂ laser in some of these conditions.

By combining the two operational modes (excision and vaporisation) of CO₂ laser, patients with rhinophyma can be effectively treated. In these cases, excess soft tissue is initially excised in a relatively bloodless field using the focused laser beam. Remaining tissue can then be contoured by tissue vaporisation. The resulting char can be removed by cotton gauze soaked in hydrogen peroxide. The process of tissue vaporisation and cleansing by hydrogen peroxide can be repeated until a satisfactory cosmetic result is obtained. Complete healing by secondary intention usually takes about 2-4 weeks.

The most frequent complication of CO₂ laser therapy is hypertrophic scarring. Others include hypopigmentation, dilated pores, postoperative haemorrhage, infection and excessive growth of granulation tissue. Another important hazard is the laser smoke (‘plume’) that occurs as a consequence of tissue vaporisation, viable human papillomavirus DNA has been isolated. An adequate smoke evacuation unit is essential.
 

4. LASERS FOR TREATING VASCULAR LESIONS (Table 3)

4.1. Argon Laser

Argon lasers have been reported to be effective in the treatment of both vascular and pigmented lesions. They emit continuous, or shuttered continuous wave systems and use argon gas as the active medium. These systems emit light in the blue-green spectrum of the electromagnetic radiation. Haemoglobin and melanin are the principal chromophores of the argon laser. Haemoglobin is only partially sensitive to the argon laser emissions. This leads to a significant degree of scattering of laser energy in the dermis. In addition, a proportion of the light is absorbed by the melanocytes. This results in unwanted epidermal damage such as burning and blistering, and a reduction in the amount of energy reaching the dermal vessels. Furthermore, argon lasers generate low power emissions, resulting in non-selective thermal damage with an increased incidence of dermal fibrosis and scarring.

Argon lasers continue to have a role in the treatment of mature, hypertrophic port wine stains in adults. Other vascular lesions that have been successfully treated by the argon laser include small haemangiomas, cherry angiomas, telangiectasias, angiokeratomas and venous lakes. Because argon laser light is absorbed by melanin, these systems have been applied for the treatment of melanocytic pigmented lesions such as pigmented naevus, freckles and lentigines. Argon lasers have also been used as energy sources for other laser systems, for example, the continuous dye laser.

4.2. 577 or 585 nm Dye Lasers

Dye lasers emit wavelengths that are selectively absorbed by oxyhaemoglobulin rather than epidermal melanin. In these systems, various organic dyes are used as the active medium to generate yellow light with wavelengths of either 577 or 585 nm. Pulsed dye lasers have been shown to be highly successful in the treatment of port wine stains. Lesions that show a better response are those that are located on the neck, lateral face and eyelids. Macular lesions and lesions in children also tend to be more responsive. Age is not a limiting factor for the use of these systems. Superficial vascular lesions other than port wine stains also respond to the pulsed dye laser. Telangiectasia especially those that occur after sclerotherapy for varicose veins are particularly responsive. The dye laser is also used for the treatment of proliferative haemangiomas that obstruct vital structures such as the eye. Complete resolution is obtained if the lesion is treated at an early stage. Others vascular lesions treated include poikiloderma of Civatte, facial spider angiomas, and the telangiectatic component of rosacea and pyogenic granuloma. Pulsed dye laser has also been successfully employed in the treatment of viral wart, although the precise mechanism by which this is achieved remains speculative.

Hexascans are automated scanning devices that can be connected to argon-pumped tunable dye lasers for the treatment of large areas of superficial vascular malformations. In contrast to the pulsed-dye laser, it is effective in the treatment of hypertrophic port-wine stains and thicker haemangiomas but paler lesions tend to be less responsive. It can also be applied to the treatment of other cutaneous vascular lesions.

Complications following the use of the pulsed dye laser are relatively uncommon. Purpura can be cosmetically disfiguring but will fade over a two weeks period. Acute changes such as the level of discomfort, scaling, vesiculation or crusting are energy dependent and can be reduced by careful monitoring of the tested area. Local anaethesia using EMLA may sometimes be necessary to relieve the associated discomfort and should be applied 60 minutes preoperatively. Scarring occurs in less than 1% and is often associated with rubbing or scratching the lesion after the procedure. Hypopigmentation or hyperpigmentation is not uncommon and usually resolves after a few months. Hexascans do not cause purpura, but its other side effects are otherwise similar.

4.3. Copper Vapour Laser

In these systems, pieces of copper metal placed in a ceramic tube are melted to form vapour. Neon gas is added to improve the discharge quality of the medium. The system produces yellow light with a wavelength of 578 nm and green light at 511 nm. Yellow light is suitable for the treatment of vascular lesion, whereas green light is used for pigmented conditions.

Although both the dye and copper vapour systems emit radiation of similar frequencies, there are several important differences between them. The laser light delivered by the copper vapour system is rapidly pulsed with a pulse duration of 20 ns. The time between each pulse is 67 us, giving a frequency of 15 KHz. In contrast to the pulsed-dye system which generates 100 mJ of energy per pulse, the energy output per pulse of the copper vapour laser is only 0.2 mJ. Summation of pulses is therefore necessary to induce the desirable degree of tissue damage. To limit the thermal damage, a mechanical shutter with different shutter speed is used. The spot sizes of copper vapour systems are also much smaller (100-1,000 um). These properties of the copper vapour laser have resulted in clinical responses quite different from that of the pulsed-dye systems. Copper vapour lasers seem to induce vasoconstriction rather than intravascular coagulation as seen in the pulsed-dye system. They can, therefore, be used in combination with pulsed-dyed lasers in the treatment of large vascular condition such as hypertrophic or cobblestone port wine stains. The small spot sizes of the copper vapour lasers make them ideal for the treatment of disorders of small blood vessels such as facial telangiectasia. The green light mode of copper vapour laser has a wavelength of 511 nm and is largely absorbed by melanin. It can be used for the treatment of superficial pigmentary conditions.

4.4. Krypton Laser

These systems use Krypton gas as the active medium and generate yellow light with a wavelength of 568-575 nm as well as green light at 520-530 nm. Their clinical applications and complications are very much similar to that of the argon laser and copper vapour laser.
 

5. LASERS FOR TREATING PIGMENTED LESIONS AND TATTOOS (Table 4)

The concept of selective photothermolysis has revolutionized the role of the laser in cutaneous surgery. This has led to the development of laser systems which are now increasingly employed in the treatment of pigmented lesions and tattoos. These are the Q-switched Nd-YAG laser, the Q-switched ruby laser, the 510 nm pulsed dye laser and the Alexandrite crystal laser. Melanin and tattoo pigment are the main chromophores and are rapidly heated leading to fragmentation into small particles. Some of these small particles are removed by phagocytosis, whereas some of the epidermal pigments are removed transepidermally. As phagocytosis is an important means of pigment removal, an interval is of at least three weeks is necessary before accurate evaluation can be made. Further lightening of lesions results from a change in the optical properties of the pigment following fragmentation

5.1. Q-switched Neodymium:Yttrium-Aluminum-Garnet (Nd-YAG) Laser

This system uses a YAG crystal doped with 1-3% neodymium ions as the active medium and is powered by a high intensity flashlamp. This leads to the generation of laser with a wavelength in the invisible infrared portion of the spectrum (1 064 nm). This light beam is poorly absorbed by melanin, haemoglobin and water but well absorbed by blue-black exogenous pigment. The laser can therefore penetrate up to 1 cm into the skin with minimal epidermal damage. The non-selectivity of continuous wave Nd-YAG laser has led to the frequent development of adverse effects that include scarring and pigmentary changes. By modifying the system with Q-switching, selective photothermolysis of exogenous blue-black pigment can be achieved. At this wavelength, a spot size of 2 mm with energy level between 5-10 J/cm² is often used. By using a potassium titanyl phosphate crystal, the wavelength of Q-switched Nd-YAG laser can be halved to 532 nm (green). At this wavelength the beam is well absorbed by red, orange and purple ink. These pigments usually respond poorly to treatment by the Q-switched ruby laser. As melanin also absorbs light of this wavelength, this system has been used successfully for the treatment of benign epidermal lesions. The fluence used is usually around 2-4 J/cm² with a spot size of 2 mm.

Safety procedures for Nd-YAG laser are similar to those for the carbon dioxide laser except eye protection. Nd-YAG laser penetrates the clear goggles that are used for the eye protection for CO2 laser. Polycarbonated safety glasses are necessary to prevent corneal and retinal damage. The main complications seen in the use of Q-switched Nd-YAG laser are pigmentary changes. These occur more frequently in the use of 532 nm laser as the 1064 nm wavelength penetrates deeper and is poorly absorbed by melanin. Sun protection like the use of sunscreens is a helpful measure. As the response varies between individuals, treatment of a test area is advisable. Scarring can also rarely occur and tends to be associated with scratching to, or trauma at the lesion postoperatively.

5.2. Q-switched Ruby Laser

Since the development of the carbon dioxide and argon laser, the role of ruby laser in dermatology has diminished substantially. By modifying the system with the Q-switched device, the ruby laser has re-established itself as an important tool for the treatment of pigmented lesions. The beam has a wavelength of 694 nm and is actively absorbed by melanin, blue-black and green pigment. Spot diameters of 4-8 mm and fluences that range from 4-12 J/cm² can be used. For amateur tattoos, 4-6 treatment sessions are needed whereas professional tattoos may require 8-10 and occasionally even 20 treatment sessions. The Q-switched ruby laser is effective for the removal of blue and blue-black inks. Occasionally green and brown pigment may also respond to Q-switched ruby. Whitening of the lesions often occurs immediately after laser treatment and lasts about 20 minutes, this represents epidermal and dermal vacuolisation secondary to thermal induced steam formation. Gradual fading of the lesions, over a 5-6 week period, may then follow. In general, lower energy levels (4-7 J/cm²) and less treatment sessions (1-2 sessions) are needed for the treatment of benign pigmented lesions. In patients who do not respond to Q-switched ruby laser, other laser such as the Q-switched Nd-YAG laser can be tried.

Safety guidelines are essentially the same as for carbon dioxide laser and Q-switched Nd-YAG laser. Purpura and even punctate bleeding can occur at the treatment site if high energy intensity is used. Other complications are similar to those seen with the Q-switched 532 nm Nd-YAG laser. Transient texture change is not unusual and usually resolves after 6-8 weeks. Pigmentary change, usually hypopigmentation, can occur in up to 50% of the patients. The majority of these patients recover completely within 6 months of their treatment, although permanent hypopigmentation can occur. Darkening after cosmetic tattoo treatment may also be seen. Scarring is rare and is associated with trauma or infection.

5.3. Alexandrite Laser

This is the third Q-switched laser system designed for the treatment of tattoos. It has a wavelength of 755 nm and a pulse duration of 100 ns. A spot diameter of 3 mm is usually used with fluences that range from 4-8 J/cm². The beam is well absorbed by blue, black and green pigment, but absorbed poorly by red ink. The wavelength of this system enables deep penetration and allows the removal of pigments in the dermis. Smaller, superficial and recent tattoos are likely to respond quicker to the Alexandrite laser.

Unlike the other Q-switched laser systems, tissue splattering does not occur with the Alexandrite laser. This is likely to be due to the differences in power density of the three systems. Although the fluences are similar, the wider pulse duration of the Alexandrite system means that it has the lowest surface power density (160 mw/cm² as compared to 400 mw/cm² with the Q-switched ruby laser, and 1,000 mw/cm² with the Q-switched Nd-YAG laser). This is important as tissue and blood splattering carry the potential risk of disease transmission such as HIV and hepatitis B. Immediate whitening also occurs in the use of the Alexandrite laser. The use of higher energy levels can cause purpura and punctuate bleeding. Others complications are similar to those seen in Q-switched ruby laser.

5.4. 510 nm Pulsed Dye, Argon, Copper Vapour, Krypton Lasers

The low degree of penetration of these lasers result in poor efficacy except for superficial pigmented lesions. They are mainly used in the treatment of freckles, lentigines, seborrhoeic keratosis and melanocytic naevi. The result in treating naevus of Ota, chloasma or other dermal pigmented disorders are poor. The 510 nm pulsed dye laser is however effective in the removal of tattoos containing red, purple, yellow and orange pigment.
 

6. LASER THERAPY IN SOCIAL HYGIENE SERVICE

Laser therapy had been started in Social Hygiene Service since this form of hi-tech treatment had been introduced to the field of dermatology in Hong Kong. However, due to the constringency of resource, there are only two laser machines available in the service, leading to a lot of limitations in the treatment. At the moment, copper vapour laser is available in Yung Fung Shee Dermatological Clinic while krypton laser in Yaumatei Dermatological Clinic. (Table 5) These two laser machines are able to emit yellow light and green light, thus they can be used to treat a variety of vascular and epidermal pigmented lesions. They are good in treating telangiectasia and purplish-dark hypertrophied portwine stain in adult. However they are not suitable to treat the portwine stain in children because of the relatively high incidence of scarring. They are also ineffective in treating dermal pigmented lesions, such as naevus of Ota, chloasma and tattoo.

Both these two machines in Social Hygiene Service are mainly manual-driven, therefore the treatment depends much on the experience of the operators. Good judgment of treatment endpoints are important in order to achieve good result. (Table 6) The power and the spot size of the handpiece of these two machines are relatively small, hence it is very time consuming in treating large area of lesions like portwine stain.

Laser therapy has been promoted and in fact has been proven as an effective treatment modality in a lot of dermatological conditions. However, they are not without risks and their end results are variable in individual patient. Before starting the treatment, the operator needs to consider carefully about the indications and the possible risks. (Table 7) One should be very cautious in dealing with patients who have keloid tendency, who are prone to post-inflammatory pigmentary changes and who are demanding persons. Cerain areas are considered as “dangerous areas” where scarring is more likely to occur, such as angle of jaws, mandibular area, presternal area, shoulders and upper arms. Risks and limitations of various forms of therapy should be fully explained to the patients, so that they will have psychological preparation and will not have over-expectation before the treatment.

Precautions that should be taken by the trained operators and nurses during the laser therapy (Table 8, 9), as these are important to the safety of both medical personnel and patients. Clinical photograph with good quality should be taken before and after the treatments for comparison and documentation. Finally, full explanation about the after-care should be given to patients in detail in order to minimized the complications. (Table 10)
 

Table 1: Classification of Laser Machines

Carbon dioxide                       10,600 nm      Infrared

Argon                                     488, 514 nm   blue-green

Organic dye (rhodamine,         504 nm            green
fluorescein, coumarin,
acridine red) (400-1,000 nm)  577, 585 nm     yellow

Copper vapour,                        511 nm             green
copper bromide                        578 nm             yellow

Krypton                                  521, 530 nm      green
                                               568 nm             yellow

Neodymium:YAG
(yttrium-aluminum-garnet)      1064 nm            infrared

KTP (potassium-titanyl
-phosphate)
(double frequency YAG)        532 nm               green

Ruby                                       694 nm               red

Alexandrite                             755 nm                red

Table 2: Clinical Applications of the Carbon Dioxide Laser

Lesions where the CO₂ laser is potentially the treatment of choice:

Actinic cheilitis, bowenoid papulosis, cutaneous resurfacing procedures, epidermal nevus, rhinophyma, sublingual keratosis

Lesions where the use of CO₂ laser may offer better results or facilitate the procedure:

Tumours: squamous cell carcinoma in-situ, superficial multifocal basal cell carcinoma, neurfibromas, giant trichoepitheliomas, seborrheic keratosis, syringomas, xanthelasma.

Infection: extensive or large condyloma acuminatum, verruca vulgaris, recalcitrant wart, debridement of burns or infected ulcer, cutaneous infection such as leishmaniasis.

Vascular: adenoma sebaceum, cherry angioma, lymphangioma circumscriptum, angiokeraomas, pyogenic granulomas, granuloma faciale.

Other: cosmetic excisional surgery, lichen planus of the penis, Hailey-Hailey disease, chondrodermatitis nodularis helicis chronicus, oral florid papillomatosis, xanthelasma

Lesions that better results can now be achieved using newer lasers:

Cafe-au-lait spots, ephelides, labial lentigines, lentigines, port wine stain, tattoos, telangiectasia

Table 3: Lasers Used in the Treatment of Vascular Lesions

Characteristics:

Clinical Applications:

Portwine stain  , telangiectasias, cherry angioma, rosacea, pyogenic granuloma, spider naevi, venous lake, angiofibroma, angiokeratoma, lymphangioma
 

Table 4: Lasers Used in the Treatment of Pigmented Lesions and Tattoos

Characteristics:

Clinical Applications:

Freckle, lentigo, melanocytic naevus, seborrhoeic keratosis, cafe-au-lait, mucosal melanosis, naevus of Ota, melasma, Mongolian?/FONT>s spot, tattoo

QS: Q-switched, Alex: Alexdandrite, Nd-YAG: Neodymium: Yttrium-Aluminum-Garnet

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Table 5: Laser Machines Available in SHS

Copper Vapour Dermatological Laser System in YFS Dermatology Clinic
(Visiray-VisErase VCM-03)

Specifications:

1. Green (511 nm): 0.9 W (at 0.4 mm spot size)
2. Yellow (578 nm): 0.7 W (at 0.4 mm spot size)
3. Spot Size: 0.1 mm, 0.15 mm, 0.4 mm, 0.8 mm
4. Focused beam
5. Exposure Modes: Continuous, Pulse
6. Air cooled

Krypton Dermatological Laser System in YMT Dermatology Clinic
(HGM-SURGICA K1)

Specifications:

Green (520-530 nm): 2.0 W (at 1.0 mm spot size)

Yellow (568-575 nm): 1.0 W (at 1.0 mm spot size)

Spot Size: 0.1 mm, 1.0 mm

Collimated beam

Exposure Modes: Continuous, Pulse

Internal water cooled

Table 6: Operating Techniques

Method:

Tracing with the handpiece (for example: telangiectasia)

Painting with the handpiece (for example: portwine stain)

Recommended starting power and spot size (use the minimal power as possible):

VisErase VCM-03
– 0.4 W with 0.4 mm spot size (Continuous wave)

SURGICA K1
– 0.7 W, 0.20 seconds pulse duration, with 1 mm spot size (Pulsed)

Treatment endpoint:

Tissue Temperature         Tissue change         Clinical observation

50 degree C                   Protein denatured     Blanching (whitening)

100 degree C                 Water vaporized       Shrinkage (greying)

100-150 degree C         Tissue carbonized     Charring (Blacking)

> 175 degree C             All vaporized            Smoky plume,Blubbling sound
                                                                      Reduced in volume

Level reached                 Clinical observation

Epidermis                       Grey

Papillary dermis              Pink (superficial dermal capillaries)

Reticular dermis             White with yellow spots (sebaceous glands)

Table 7: Complications & Hazards of Laser

Possible complications of laser therapy:

1) Immediate erythema, oedema, pain, exudation, purpura
2) Secondary infection
3) Pigmentary changes: hyperpigmentation, hypopigmentation
4) Textural changes, atrophy
5) Scarring, keloid

Potential Hazards of Laser Machine:

• 1) Hazard to eye
      Retina, especially macula: permanent visual loss
      (Suitable protective eye goggles, eye-shields)
• 2) Hazard to skin
      Severe burns & scarring
      (Training & experience)
• 3) Electrical hazard
      High voltage: life threatening
      (Strictly follow the safety precautions)
• 4) Hazards from fumes & vaporized tissues
      HPV, HIV
      (Fume evacuator, good ventilation, mask)

Table 8: Precautions in Laser Therapy

1) ALWAYS wear safety goggles with recommended filters whenever the laser is in use.

    Operator’s goggles:

        VisErase VCM-03
        – Green: Orange filter
        – Yellow: Grey filter

        SURGICA K1
        – Green/Yellow: Green filter

    Patient’s goggles:   Red filter

2) ALWAYS lock the door of the room during treatment.
3) NEVER look directly into the laser beam; or at scattered or reflected laser light.
4) NEVER point the laser handpiece at any person except at the treated area.
5) NEVER remove any covers from the cabinet of the machine and attempt to repair.
6) NEVER use the laser in the presence of flammable anaesthetics.
7) NEVER step on or abruptly bend the fibre-optic cable.
8) NEVER move the laser machine during operation or within 30 minutes of turning off for VisErase VCM-03.
9) Do NOT turn off the machine immediately after treatment. Wait for 30 minutes for VisErase VCM-03 and 5 minutes for SURGICA K1.
10) Do NOT turn off the main electrical switch.

Table 9: Procedures that must be Taken by Nursing Staff

Before treatment:

1) Turn on the laser machine for warm up
        40 minutes for VisErase VCM-03
        45 seconds for SURGICA K1
2) Written consent after explanation of the procedures
3) Take clinical photograph
4) Ensure the patient having eye-protection
5) Prepare local anaesthetics if necessary
        Lignocaine (without adrenaline)
        Emla cream (1 hour before treatment with Tegederm occlusion)
        Novesin eyedrop if eye-shields are necessary
6) Lock the door and turn on the warning lamp

During treatment:

1) Ensure that the patient has eye-protection all the time
2) Measure the treatment time
3) Plume suction if necessary

After treatment:

1) Apply antiseptic cream (silver sulphadiazine, fucidin) or emollient (aqueous cream) for the patient
2) Arrange follow-up appointment
3) In between treatment, keep the machine at Standby mode for SURGICA K1
4) After treatment for all patients, wait for 30 minutes for VisErase VCM-03 and 5 minutes for SURGICA K1 before turn off the machine

Table 10: Aftercare Following Laser Treatment

1) Expect a sunburn-like reaction with possible blistering within the first 24-48 hours. Pain is usually minimal and can be relieved with either Panadol and/or cool soaks with a wash cloth.

2) A crust or scab may occur and should last for 7-14 days. Do not pick off the scab!! Just let it fall off at its own pace.

3) Keep the area clean and dry until the scab/crust falls off. Wash gently with soap and water and apply a thin layer of moisturizer or antibiotic ointment.

4) Once the scab/crust has come off the area may look pink and even slightly depressed or indented. Both the pinkness and depression should improve over the next several weeks to months.

5) Avoid direct sunlight or sun exposure to the treated areas for 3-6 months. Use at least an SPF of 15 or greater sunscreen, or wear a hat or other protective clothing (preferably both). Be aware that unprotected sun exposure can result in an uneven repigmentation, producing brown spots that can take months to fade away and in rare cases may be permanent.

6) Be patient!! It may take up to three months to adequately judge the true response of your  condition to the laser treatment. DON’T HESITATE TO CALL IF YOU HAVE ANY QUESTIONS OR PROBLEMS!!