8.4 Laser dermatology and cosmetic treatments

Laser dermatology harnesses light energy to treat skin conditions. From tattoo removal to hair reduction, lasers target specific skin components while minimizing damage to surrounding tissues. This precision allows for effective treatments with reduced recovery times.

Advances in laser technology have expanded treatment options. Fractional lasers, picosecond devices, and combination therapies offer improved results for various skin concerns. As research continues, laser dermatology promises even more innovative solutions for skin health and aesthetics.

Laser-tissue interactions in dermatology

• Laser-tissue interactions involve the absorption, scattering, and transmission of laser energy in biological tissues
• The primary chromophores in the skin that absorb laser energy include melanin, hemoglobin, and water
• Selective photothermolysis is a key principle in laser dermatology involves targeting specific chromophores while minimizing damage to surrounding tissues
• Thermal effects of lasers on tissues include coagulation, vaporization, and ablation depending on the laser parameters and tissue properties

Laser wavelengths for dermatological treatments

Ablative vs non-ablative lasers

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• Ablative lasers (CO2 and Er:YAG) remove the epidermis and upper dermis causing tissue vaporization and collagen remodeling
• Non-ablative lasers (Nd:YAG, diode) penetrate deeper into the dermis without removing the epidermis leading to collagen stimulation and skin tightening
• Ablative lasers have higher risks of side effects (erythema, edema, infection) but provide more dramatic results compared to non-ablative lasers
• Non-ablative lasers have shorter recovery times and lower risks but may require multiple treatments for optimal results

Fractional laser technology

• Fractional lasers create microscopic thermal zones (MTZs) of treated tissue surrounded by untreated skin
• Fractional photothermolysis allows for faster healing and reduced downtime compared to full-field resurfacing
• Fractional ablative lasers (CO2, Er:YAG) are used for deeper wrinkles, scars, and skin texture improvement
• Fractional non-ablative lasers (1540nm, 1550nm) are used for mild to moderate photoaging, pigmentation, and acne scars

Laser treatments for pigmented lesions

Q-switched lasers for tattoo removal

• Q-switched lasers (Nd:YAG, Ruby, Alexandrite) deliver high-energy, nanosecond pulses to fragment tattoo pigments
• Different wavelengths are used to target specific colors (532nm for red/orange, 694nm for green/blue, 1064nm for black)
• Multiple treatments are required for complete tattoo removal with 4-8 week intervals between sessions
• Risks include hypopigmentation, hyperpigmentation, and scarring especially in darker skin types

Pulsed dye lasers for vascular lesions

• Pulsed dye lasers (PDL) target hemoglobin in blood vessels to treat vascular lesions (port wine stains, hemangiomas, telangiectasias)
• PDL wavelengths range from 585-595nm with pulse durations of 0.45-40ms to match the thermal relaxation time of the target vessels
• Purpura (bruising) is a common side effect that resolves within 7-14 days
• Multiple treatments are often necessary for optimal clearance of vascular lesions

Laser hair removal techniques

Alexandrite vs diode lasers

• Alexandrite (755nm) and diode (800-810nm) lasers are commonly used for hair removal targeting melanin in the hair follicle
• Alexandrite lasers have a shorter wavelength and are more effective for finer, lighter hair and lighter skin types (Fitzpatrick I-III)
• Diode lasers have a longer wavelength and are safer for darker skin types (Fitzpatrick IV-VI) with a lower risk of epidermal damage
• Both lasers require multiple treatments (6-8) at 4-8 week intervals for permanent hair reduction

Treatment protocols and side effects

• Proper patient selection, skin typing, and test spots are essential to minimize side effects
• Pre-treatment shaving and cooling of the skin (contact or air cooling) are used to protect the epidermis
• Common side effects include erythema, edema, and folliculitis which typically resolve within a few days
• Rare complications include blistering, crusting, hyperpigmentation, and hypopigmentation

Laser skin resurfacing procedures

CO2 lasers for wrinkles and scars

• CO2 lasers (10,600nm) are the gold standard for deep wrinkles, severe photodamage, and atrophic scars
• Ablative CO2 resurfacing removes the epidermis and upper dermis stimulating collagen remodeling and skin tightening
• Fractional CO2 lasers offer shorter downtime and faster healing compared to full-field resurfacing
• Risks include prolonged erythema, hyperpigmentation, hypopigmentation, and scarring

Erbium:YAG lasers for superficial resurfacing

• Erbium:YAG lasers (2,940nm) have a higher absorption in water compared to CO2 lasers resulting in more superficial ablation
• Er:YAG lasers are used for fine lines, mild to moderate photodamage, and superficial scars
• Fractional Er:YAG lasers provide controlled resurfacing with reduced downtime and side effects
• Multiple treatments may be required for optimal results with Er:YAG lasers

Laser safety considerations in dermatology

Eye protection and skin cooling

• Appropriate eye protection (goggles, shields) specific to the laser wavelength must be worn by the patient, operator, and any observers
• Skin cooling techniques (contact cooling, air cooling, cryogen spray) are used to protect the epidermis and reduce pain during treatment
• Adequate skin cooling helps to minimize the risk of side effects such as blistering, crusting, and post-inflammatory hyperpigmentation

Pre- and post-treatment care

• Pre-treatment instructions include avoiding sun exposure, tanning, and certain medications (isotretinoin, aspirin) that may increase the risk of complications
• Post-treatment care involves gentle cleansing, moisturizing, and sun protection to promote healing and prevent hyperpigmentation
• Patients should be informed of the expected downtime, side effects, and potential complications associated with each laser procedure
• Close follow-up and monitoring are essential to identify and manage any adverse reactions or suboptimal outcomes

Combination treatments with lasers

Lasers with topical medications

• Laser-assisted drug delivery involves using lasers to enhance the penetration of topical medications into the skin
• Fractional lasers create microchannels that allow for increased absorption of topical agents (retinoids, growth factors, platelet-rich plasma)
• Combining lasers with topical medications can improve the efficacy of treatments for photodamage, melasma, and scars
• Proper timing and formulation of topical agents are crucial to optimize the synergistic effects and minimize any potential adverse reactions

Lasers with other energy-based devices

• Combining lasers with other energy-based devices (radiofrequency, intense pulsed light, ultrasound) can provide enhanced clinical outcomes
• Radiofrequency devices (monopolar, bipolar, fractional) can be used in combination with lasers for skin tightening and contouring
• Intense pulsed light (IPL) can be used with lasers for the treatment of pigmentation, redness, and photoaging
• Ultrasound devices (microfocused, high-intensity focused) can be combined with lasers for skin lifting and collagen stimulation

Future advancements in laser dermatology

Picosecond lasers for pigmentation

• Picosecond lasers deliver ultrashort pulses (trillionths of a second) that target pigment particles more efficiently than traditional Q-switched lasers
• Picosecond lasers (755nm, 1064nm) are used for the treatment of tattoos, benign pigmented lesions, and melasma
• The shorter pulse duration of picosecond lasers allows for more photoacoustic effects and less thermal damage to surrounding tissues
• Picosecond lasers have shown promising results in treating pigmentary disorders with fewer treatments and reduced side effects compared to conventional lasers

Laser-assisted drug delivery systems

• Novel laser-assisted drug delivery systems are being developed to enhance the targeted delivery of therapeutic agents into the skin
• Fractional lasers can be used to create microchannels for the delivery of drugs, growth factors, and stem cells
• Nanoparticle-based drug delivery systems can be activated by specific laser wavelengths for controlled release and enhanced penetration
• Laser-assisted delivery of biologics and gene therapy may offer new treatment options for genetic skin disorders and skin cancer