Following the introduction of the ruby laser in 1963, it was initially employed for treating skin conditions. The subsequent development of CO₂ laser and argon lasers saw their utilization in addressing benign vascular birthmarks, but the undesired side effect of scar formation was deemed unacceptable. Over the past few decades, remarkable advancements in laser technology have resulted in a diverse range of lasers operating at various wavelengths. These lasers are now extensively used in dermatology for treating skin conditions, including resurfacing, pigmented lesions, tattoo removal, scar reduction, wrinkle treatment, and hair removal. 

Dermatology focuses on the skin's structure, functions, and associated diseases. It utilizes laser energy absorption by target tissues to achieve therapeutic outcomes. The absorption characteristics vary with the laser wavelength, and there is a wide array of lasers available with distinct wavelengths. Various lasers used in dermatology include argon laser (488 nm & 514 nm), tunable dye lasers (585 nm to 595 nm), doubled Nd:YAG (532 nm), krypton laser (568 nm), alexandrite laser (755 nm), Nd:YAG (1064 nm), Er:YAG (2940 nm), and CO₂ laser (10.6 μm). The pulse width of these laser systems ranges from milliseconds to nanoseconds (pulsed), or the laser may operate continuously (CW).

Evolution of Laser Technology in Dermatology

The concept of LASER involves the amplification of light to produce coherent light beams. This technological advancement traces its roots back to fundamental physics research, with Albert Einstein introducing the idea of stimulated emission in the early 20th century. Theodore Maiman at Hughes Aircraft Company then created the first operational laser in 1960.

For centuries, artificial light sources have been utilized for the treatment of various skin conditions. The Finsen lamp, back in 1899, was employed for lupus vulgaris, wound healing, and rickets, while the treatment of pigmented and vascular lesions using ruby and Nd:YAG lasers was reported by Dr. Leon Goldman's group from 1963 to 1973. Dr. Goldman's contributions sparked a rapid expansion of treatment concepts involving lasers like helium neon, Q-switched, argon, and carbon dioxide lasers.

The introduction of selective photothermolysis in 1983 by Anderson and Parrish laid the foundation for treating vascular lesions. Modern devices such as pulsed dye lasers, long-pulsed alexandrite lasers, pulsed diode lasers, long-pulsed Nd:YAG lasers, and intense pulsed light sources have further enhanced the treatment of vascular lesions, minimizing side effects and optimizing clinical outcomes.

Over the years, lasers have gained FDA approval for cosmetic skin resurfacing (2004) and melasma (2005), marking a significant milestone. The field of dermatology has witnessed the evolution of lasers, turning them into valuable treatment modalities for a wide range of skin conditions. The therapeutic use of lasers has exceeded expectations, showcasing their diverse applications in modern dermatology.

Various Lasers Used in Dermatology

Ablative and Non-Ablative Laser Treatments

Ablative and non-ablative laser treatments are both used in dermatology for various skin conditions, and they differ in their mechanisms and applications.

Ablative Laser Treatment

Ablative laser treatment involves the removal of thin layers of skin by vaporizing the targeted tissue. It works by delivering intense wavelengths of light that are absorbed by water in the skin cells and causes the cells to evaporate.

• Applications:
  • Wrinkle reduction: Ablative lasers can stimulate collagen production and improve the appearance of wrinkles.
  • Scar reduction: They are used to treat scars, including acne scars and surgical scars.
  • Skin resurfacing: Ablative lasers are effective for overall skin rejuvenation and addressing sun damage.
• Examples of Lasers used in Ablative Laser Treatment:
  • CO₂ (carbon dioxide) lasers
  • Erbium lasers

Non-Ablative Laser Treatment

Non-ablative laser treatment target the dermis (the deeper layer of skin) without removing the outer layer. It works by heating the targeted tissue to stimulate collagen production and promote skin tightening.

• Applications:
  • Wrinkle reduction: Non-ablative lasers are used to improve fine lines and wrinkles by promoting collagen remodeling.
  • Vascular lesions: They can target blood vessels and are used for conditions like spider veins or vascular birthmarks.
  • Skin tightening: Non-ablative lasers can help tighten loose or sagging skin.
• Examples of Lasers used in Non-Ablative Laser Treatment:
  • Nd:YAG lasers
  • Alexandrite lasers
  • Diode lasers

Ablative laser treatment generally provides more dramatic results but may require a longer recovery time due to the removal of the outer skin layers, while non-ablative laser treatments have a shorter recovery time as they leave the outer skin intact, but they may require multiple sessions for optimal results.

The choice between ablative and non-ablative laser treatment depends on the specific skin concerns, the desired results, and individual factors like skin type and downtime tolerance.

Laser Interactions with Different Components of the Skin

The basics of laser applications in dermatology involve three key factors: melanin, hemoglobin, and scattering. 

The initial pigment engaged by the laser is melanin, which serves as the skin's protective barrier against excessive sunlight, particularly UV rays. The impact of melanin's physical characteristics on laser surgery varies based on the type of treated lesion. Melanin is predominantly found in the epidermis and hair follicles, absorbing diverse wavelengths across the electromagnetic spectrum.

Hemoglobin, containing iron, significantly hinders laser transmission into tissues. The optimal absorption range for hemoglobin is between 514 nm - 590 nm, with absorption peaks at 415 nm (blue), 540 nm (green), and 577 nm (yellow). The blue band of oxyhemoglobin is employed to target superficial microvessels, penetrating deeper into target tissues. Blood absorption is primarily governed by oxyhemoglobin that exhibit strong bands in the UV, blue, green, and yellow regions. The 577 nm (yellow) absorption band of oxyhemoglobin is selected for selective photo-thermolysis in targeting superficial microvessels. The blue band (420 nm) or higher band at 900 nm can penetrate more deeply, affecting deeper target tissues.

Scattering plays a crucial role in the interaction between lasers and target tissues during laser treatment. The target tissue can absorb laser energy that is either scattered or reflected. As the laser penetrates the tissue, it undergoes scattering due to interactions with water, lipids, and cellular membranes. Shorter wavelengths in the visible region exhibit more scattering compared to longer wavelengths. Scattering is a significant aspect of laser treatment as the energy that scatters becomes deposited in nearby tissues. The scattered light is eventually absorbed, which leads to the release of heat. Scattering serves as a mechanism for dissipating heat from the treated lesion but can result in collateral damage to non-target tissues.

What Skin Conditions Can Be Treated with Lasers?

Vascular lesions

Vascular lesions are abnormalities or irregularities in the blood vessels that can affect the appearance of the skin. These lesions involve blood vessels and can manifest in various ways, including visible red or purple discolorations on the skin.

Laser technology has proven successful in addressing various vascular lesions that encompasses conditions like superficial vascular malformations (such as port-wine stains), facial telangiectases, hemangiomas, pyogenic granulomas, Kaposi sarcoma, and poikiloderma of Civatte. A range of lasers has been employed for treating these conditions, including argon, APTD, KTP, krypton, copper vapor, copper bromide, pulsed dye lasers, and Nd:YAG.

Argon (CW) lasers causes non-specific thermal injury and scarring and so it has been largely replaced by yellow-light quasi-CW and pulsed laser therapies. The pulsed dye laser stands out as the preferred choice for most vascular lesions due to its exceptional clinical effectiveness and low-risk profile. Its significant spot size (5 to 10 mm) enables the quick treatment of large lesions. Common side effects include postoperative bruising (purpura), lasting 1-2 weeks, and transient pigmentary changes. Crusting, textural alterations, and scarring are rarely observed.

Recent advancements in the V-beam technology offer an ultra-long pulse duration that results in more uniform blood vessel damage and reduced purpura compared to earlier pulsed dye lasers. Dynamic cooling features enhance comfort during treatment and enable the safe and effective delivery of higher energy levels, thereby requiring fewer sessions.

Vascular malformations associated with smaller, more superficial blood vessels typically respond better to treatment than those involving deeper, larger vessels often found in older individuals. Early initiation of treatment is recommended, with an average fading of 80% observed after 8 to 10 sessions. Additional treatments may be necessary in case of lesion recurrence.

While quasi-CW lasers also yield effective outcomes, they may be linked to a higher incidence of scarring and textural changes. Common side effects include mild erythema, edema, and transient crusting. It's worth noting that non-laser intense pulsed light devices can also be employed for the treatment of vascular lesions.

Pigmented Lesions and Tattoos

High-energy, melanin-specific, Q-switched (QS) laser systems have proven effective in lightening or eliminating various pigmented lesions. Treatable pigmented lesions include freckles, birthmarks (including some congenital melanocytic naevi), blue naevi, naevi of Ota/Ito, and Becker naevi. These laser systems target pigmented lesions by directing their energy specifically to melanosomes, the minute granules containing melanin within pigment cells. The outcomes of laser treatment depend on factors such as the depth of melanin and the color of the lesion, which can be somewhat unpredictable. Superficial pigment is best addressed with shorter-wavelength lasers, while deeper pigment removal requires longer-wavelength lasers penetrating greater tissue depths. Caution is advised when using lasers on skin of color, as it may lead to permanent hypopigmentation or depigmentation. Successfully treated lesions might experience recurrence.

Before laser treatment for pigmented lesions, any lesion displaying a typical feature should undergo biopsy to rule out malignancy. The treatment of congenital melanocytic naevi remains a debated topic, with the long-term effects of lasers on promoting melanoma not fully understood but considered low risk.

QS laser systems selectively eliminate tattoo pigment without causing significant damage to the surrounding skin. The modified pigment is cleared by white blood cells, tissue macrophages. Laser choice depends on tattoo ink color, depth, and chemical nature. Multiple treatments (usually two to ten) are often required, with yellow, orange, and green being the most challenging colors to remove.

• Black: Q-Switched ruby, alexandrite, or Nd:YAG lasers
• Blue and green: Q-Switched ruby, alexandrite lasers
• Yellow, orange, red: Q-Switched Nd:YAG or PDL lasers

Similar to other laser treatments, pigmentary and textural changes, including scars, may occur. Picosecond Nd:YAG and alexandrite lasers have demonstrated more effective removal of exogenous pigment compared to Q-Switched lasers.

Hair Removal

Hair removal stands is one of the most widely sought non-surgical aesthetic laser treatments globally. Laser hair removal is a non-invasive procedure that uses pulses of concentrated light to remove excess or unwanted hair from the face or body. In the process of laser hair removal, hair follicles are vaporized by the laser. The laser focuses on the pigment, or melanin, in the hair, emitting light within the wavelength range of 300 to 1,200 nanometers (nm), a level at which melanin absorbs light. Melanin absorbs the laser's energy and disperses it to the surrounding follicular structures, ultimately destroying the hair matrix (cells that aid in hair follicle growth) and stem cells located in the bulge of the hair follicle.

Various types of lasers are available for hair removal, each catering to specific needs:

• Ruby laser: Utilizes synthetic ruby crystals to emit red light, effective for lighter skin types with dark hair.
• Diode laser: Suitable for darker skin tones, this laser type penetrates more deeply with less damage to the skin.
• Intense Pulse Light (IPL) or Broadband Light (BBL): Employs high-intensity pulses of multicolored light delivered by a flash lamp, suitable for darker skin and covering larger body areas.
• Alexandrite laser: Well-suited for removing lighter-colored hair, it penetrates more deeply into the skin.
• Neodymium-doped Yttrium Aluminium Garnet (Nd: YAG) laser: Suitable for all skin types, this laser offers enhanced penetration with minimal skin damage.

Facial Wrinkles, Scars, and Sun-Damaged Skin

Facial laser resurfacing is a cosmetic procedure that uses laser technology to improve the appearance and texture of the skin on the face. This treatment is commonly employed to address various skin concerns, including wrinkles, scars, sun damage, and other signs of aging. Facial laser resurfacing employs high-energy, pulsed, and scanned lasers for rejuvenation.

Pulsed CO₂ and erbium:YAG lasers have demonstrated success in diminishing facial wrinkles, acne scars, and sun-damaged skin. The CO₂ laser, known for its high-energy pulsed and scanned capabilities, is widely regarded as the gold standard in facial rejuvenation. Typically, patients undergoing CO₂ laser treatment experience a substantial 50% improvement. Post-treatment side effects include temporary tenderness, redness, swelling, and scarring. The redness and tenderness may persist for several weeks as new skin regenerates over the treated area (ablative laser systems). Caution is essential when treating individuals with darker skin tones, as there is a risk of long-term permanent pigmentation loss or variation.

Erbium:YAG laser yields comparable results and side effects as that of CO₂ laser. Despite their side effect profile and extended recovery period, these ablative laser systems, when used appropriately, can deliver outstanding outcomes.

Non-ablative laser treatments have recently been employed for dermal modeling, where the term 'non-ablative' indicates the heating of dermal collagen while safeguarding surface skin cells (epidermis) through cooling. Multiple sessions are usually required for achieving skin smoothing.

Keloids and hypertrophic scars

Keloids and hypertrophic scars are challenging to eliminate with conventional methods. An alternative is the use of vaporizing lasers like CO₂ and erbium:YAG that offer an effective option to traditional surgery. More recently, pulsed dye laser (PDL) has been applied to enhance hypertrophic scars and keloids that require multiple sessions or concurrent use of intralesional injections for optimal results. PDL has been reported to reduce redness while enhancing the texture and flexibility of the scar.

Techniques Used in Dermatology and Cosmetic Medicine

Dermatology and cosmetic medicine encompass a variety of techniques aimed at maintaining skin health, addressing skin conditions, and enhancing aesthetic appearance. 

Low-Level Laser Therapy (LLLT), also known as cold laser therapy or photobiomodulation, is a medical treatment that utilizes low-level lasers or light-emitting diodes (LEDs) to stimulate cellular function. Unlike surgical or aesthetic lasers that produce heat and cut or destroy tissue, LLLT uses low-level, non-thermal light to trigger biological processes within cells. The light energy is typically applied to the skin, and it penetrates into the underlying tissues.

Various techniques are employed for applying LLLT to patients. One method involves tissue saturation by pressing the emitter or probe against the skin and moving systematically across the area to ensure complete coverage. Scanning or back-and-forth movement may be employed for saturation, with firm pressure enhancing laser tissue penetration. Another approach targets trigger points, while a third involves acupuncture point stimulation or laser puncture. 

The lasers commonly used in LLLT are diode lasers based on Gallium-Arsenide (GaAs), operating within wavelength ranges such as 630 - 700 nm, 780 - 890 nm, and 900 - 1100 nm. These lasers can be continuous or pulsed. Red-light lasers, with a penetration range of 6 - 10 mm, affect the skin and superficial tissues, while near-infrared lasers penetrate 2 - 3 cm, making them suitable for medium to deep tissue structures like muscles, tendons, and joints. 

Pulsed diode lasers in the 10 - 100-watt range, with pulse widths of 100 - 200 nanoseconds, allow for deep penetration (3 - 5 cm) into body tissues without the adverse effects associated with continuous high-power output, such as excessive heat production. Pulsed lasers generally offer deeper penetration compared to continuous wave (CW) lasers of the same wavelength and average output power. These lasers are well-suited for medium and deep tissues, including tendons, ligaments, and joints.

Light-emitting diodes (LEDs) and infrared-emitting diodes (IREDs) have also found application in phototherapy, providing approximately 80 percent of the effect on tissues as lasers. Commonly used light diodes include visible red (630 nm, 640 nm, 650 nm, and 660 nm) and IRED (830 nm, 880 nm, and 950 nm). LEDs offer advantages such as broad coverage due to non-coherent light and no tissue damage. However, they necessitate higher power output and cover large treatment areas, often employing arrays of 40 - 60 diodes.

Lipolysis, a method for laser body fat removal, is gaining popularity through the transdermal application of light at 1060 nm using both direct and fiber-coupled diode lasers. The 1060 nm light enhances selectivity by maximizing the absorption ratio in fat tissue compared to water absorption. At the appropriate intensity, this wavelength raises the temperature in adipose fat tissue just below the dermis, leading to cell degeneration. Over a few weeks, the body naturally eliminates the degenerated adipose tissue and allow the skin to adjust and potentially avoiding the loose, saggy skin appearance often associated with liposuction or certain weight loss surgeries. To prevent discomfort and dermal damage, skin surface cooling, similar to hair removal procedures, is employed. A novel tool incorporates surface cooling that maximizing process efficiency for fat removal. This method falls under non-invasive body contouring method aesthetic procedure that aim to reshape and improve the appearance of the body without the need for surgery or significant downtime. These procedures use various technologies to target and reduce localized fat deposits, tighten skin, and improve overall body contours. Non-invasive body contouring is a popular choice for individuals seeking cosmetic enhancements without the risks and recovery associated with invasive surgical procedures.

Skin tightening, another popular aesthetic procedure, is often performed independently or as a complement to lipolysis. It operates by heating and subsequently photocoagulating (a process that uses light to coagulate or clot blood vessels or tissues) collagen. Conversely, wrinkle removal and skin resurfacing depend on laser light absorption by dermal cells, with shorter wavelengths enabling efficient melanin absorption. These procedures typically employ lasers at 810 and 915 nm, although some system manufacturers may prefer 1550 nm, where water absorption dominates over melanin absorption.

A variant of skin resurfacing combines a 1550 nm diode laser with an infrared CO₂ laser at 10.6 μm, known as "fractional resurfacing." In this dual approach, the CO₂ laser focuses on a small spot, pulsing as it moves across the skin, creating numerous small holes. The 1550 nm diode laser induces photocoagulation of collagen, resulting in both softening and tightening.

While most varicose vein removal procedures remain non-laser applications, smaller veins feeding larger varicose veins are increasingly treated transdermally using 940, 980, or 1470 nm diode lasers. Larger veins are typically addressed through conventional surgical means or, in some cases, with a 940 nm diode laser endovenously.

Additional aesthetic applications include acne treatment, primarily using blue-green lasers at 450 nm or 520 nm, or 1470 nm, which is highly absorbed on the skin's surface. Teeth whitening procedures commonly involve lasers at 810 nm or 980 nm.

Intense Pulsed Light (IPL) therapy, often referred to as IPL treatment or photofacial, is a non-invasive skin rejuvenation technique that uses broad-spectrum light to target various skin concerns. IPL is not a laser, but rather a high-intensity light source that emits a range of wavelengths. It is commonly used in dermatology and cosmetic medicine for several purposes, including the treatment of skin pigmentation, vascular issues, and overall skin texture.

Advantages of using Lasers in Dermatology

Laser technology has become an integral part of dermatology, offering various advantages for a wide range of applications. Some of the key advantages of using lasers in dermatology include:

• Precision Targeting: Lasers can precisely target specific tissues or chromophores (pigments or structures in the skin) without affecting surrounding areas. This precision allows for highly controlled and selective treatments.
• Customizable Wavelengths: Different types of lasers emit specific wavelengths of light, and these can be selected based on the intended treatment. This enables dermatologists to tailor treatments to address various skin conditions, such as pigmentation, blood vessels, or collagen.
• Minimized Damage to Surrounding Tissues: The selective targeting of lasers minimizes damage to surrounding healthy tissues, reducing the risk of scarring and promoting faster healing.
• Treatment Versatility: Lasers are versatile and can be used for a wide range of dermatological applications, including hair removal, skin resurfacing, tattoo removal, vascular lesion treatment, and more.
• Non-Invasive or Minimally Invasive: Many laser procedures are non-invasive or minimally invasive, meaning they do not require incisions or sutures. This results in less discomfort, shorter recovery times, and reduced risk of infection.
• Stimulates Collagen Production: Certain laser treatments, especially non-ablative lasers, stimulate collagen production in the skin. This can lead to improved skin texture, reduced fine lines, and overall skin rejuvenation.
• Effective for Various Skin Types: Advancements in laser technology have led to the development of devices suitable for different skin types and conditions. This inclusivity allows a broader range of patients to benefit from laser treatments.
• Reduced Bleeding During Surgery: When used for surgical procedures, lasers can provide precise cutting and coagulation, leading to reduced bleeding compared to traditional surgical methods.
• Targeted Treatment of Vascular Lesions: Lasers like Pulsed Dye Lasers (PDL) can effectively target and treat vascular lesions, such as spider veins and port-wine stains, by coagulating blood vessels without damaging the surrounding tissue.
• Predictable Outcomes: With proper calibration and settings, laser treatments can produce predictable and consistent outcomes that allow dermatologists to plan treatments with confidence.
• Reduced Risk of Infection: Non-invasive laser treatments minimize the risk of infection since they do not involve open wounds. This is particularly advantageous for procedures like laser hair removal.
• Cosmetic Applications: Lasers are widely used in cosmetic dermatology for procedures such as skin resurfacing, wrinkle reduction, and scar revision that contribute to aesthetic improvements.

Disadvantages of using Lasers in Dermatology

While lasers have numerous advantages in dermatology, there are also certain disadvantages and potential risks associated with their use. It's important to note that these disadvantages may vary depending on the type of laser, the specific procedure, and individual patient characteristics. Here are some common disadvantages of using lasers in dermatology:

• Risk of Hyperpigmentation or Hypopigmentation: Improper use of lasers or inadequate post-treatment care can lead to changes in skin pigmentation. Hyperpigmentation (darkening of the skin) or hypopigmentation (lightening of the skin) may occur, especially in individuals with darker skin tones.
• Risk of Scarring: Ablative lasers, if not used with precision or if the patient does not follow proper aftercare instructions, may carry a risk of scarring. This is particularly true for aggressive treatments that remove layers of skin.
• Pain and Discomfort: Some laser procedures can be associated with discomfort or pain during the treatment. Although topical anesthetics are often applied, individuals may still experience varying levels of discomfort.
• Downtime and Recovery: Ablative lasers, which remove layers of skin, often require a longer recovery period with significant downtime. Non-ablative lasers generally have less downtime but may still involve redness or swelling.
• Photosensitivity: Following laser treatment, the skin may become more sensitive to sunlight. Patients are typically advised to avoid sun exposure and use sun protection, as failure to do so can increase the risk of complications.
• Risk of Infection: While the risk is generally low for non-invasive laser treatments, invasive procedures or those involving open wounds may pose a risk of infection if proper hygiene measures are not followed.
• Uneven Results: Achieving consistent and even results can be challenging, especially with certain skin conditions or when treating larger areas. Individual responses to laser treatments can vary.
• Potential for Adverse Reactions: Some individuals may experience adverse reactions to laser treatments, such as blistering, crusting, or changes in skin texture. Pre-existing medical conditions or medications can influence these reactions.
• Multiple Sessions Required: Some laser treatments may require multiple sessions for optimal results. This can be a disadvantage for individuals seeking quick or single-session solutions.
• Cost: Laser treatments can be relatively expensive, especially if multiple sessions are required. The cost may be a limiting factor for some individuals seeking cosmetic or therapeutic procedures.
• Precautions for Specific Skin Types: Certain lasers are more suitable for specific skin types, and using the wrong laser can lead to complications. It is crucial for practitioners to consider the patient's skin type and characteristics.
• Risk of Eye Injury: Lasers can pose a risk of eye injury if proper eye protection is not used during treatment. Both practitioners and patients must wear appropriate eye shields.

Click here to know more about lasers for medical applications.