Photorejuvenation with Lasers

27 Photorejuvenation with Lasers



Cumulative damage to the skin over time from ultraviolet light results in photoaging. Photoaging changes are clinically evident as benign pigmented lesions, such as solar lentigines, freckles (ephelides), hyperpigmentation, melasma, and as benign vascular lesions, such as telangiectasias, poikiloderma of Civatte, rosacea, and cherry angiomas.1 Photorejuvenation refers to the cosmetic treatment of photoaged skin with nonablative lasers and light-based technologies (collectively referred to as lasers*).2 Treatments are most commonly performed on the face, neck, chest, and hands, but may be performed on almost any photodamaged area of the body.3 Photorejuvenation treatments reliably achieve improvements, have short postprocedure recovery times and minimal risks of complications, and are associated with high patient satisfaction.4,5



Laser Principles


Laser treatments are based on the principle of selective photothermolysis. Light-absorbing pigments in the skin, called chromophores, selectively absorb light energy and convert it to heat in the targeted lesions. The lesions are heated, damaged, and eliminated, while the surrounding skin is left unaffected. Photorejuvenation treatment of benign pigmented and vascular lesions is achieved through selectively targeting two main chromophores in the skin, oxyhemoglobin, which is found in red blood, and melanin, which is found in pigmented lesions.6


When treating red vascular lesions, laser energy is absorbed by the oxyhemoglobin chromophore. The vessel is heated, causing injury to the vessel wall and perivascular collagen damage, which results in vessel closure and obliteration. Oxyhemoglobin absorbs light between 510 and 600 nm (Figure 27-1). Lasers used for the treatment of red vascular lesions produce light in this range and include argon (510 nm), potassium titanyl phosphate or KTP (532 nm), and pulsed dye (585 nm) lasers.



When treating benign pigmented lesions, such as lentigines, light energy is absorbed by the target chromophore melanin that is contained within the melanosomes of epidermal melanocytes and keratinocytes. The melanosome is heated, ruptured, and the melanin eliminated. Melanin preferentially absorbs light between 650 and 1100 nm (see Figure 27-1). Lasers used for treatment of epidermal pigmented lesions produce light in this range and include ruby (694 nm), alexandrite (755 nm), diode (810 nm), and neodymium-doped yttrium aluminum garnet or Nd:YAG (1064 nm) lasers. The light from KTP (532 nm) and argon (510 nm) lasers has high absorption by both melanin and oxyhemoglobin and can be used to treat both pigmented and vascular lesions.


Intense pulsed light (IPL) devices emit a spectrum of wavelengths, and certain desired wavelengths can be selected with the use of filters. For example, some IPL filters have an emission peak from 500 to 670 nm and a second emission peak from 870 to 1200 nm. Melanin and oxyhemoglobin are targeted with these wavelengths. In addition, lesions at different depths are also targeted because the shorter wavelengths target more superficial lesions and the longer wavelengths target deeper lesions. In this way, a single IPL device can be used to target both vascular and pigmented lesions at a variety of depths in the skin.


Several device parameters affect the safety and efficacy of photorejuvenation treatments. These parameters include wavelength, fluence, pulse duration, and spot size (see Laser Parameters in Chapter 19, Aesthetic Principles and Consultation).




For treatment of benign pigmented lesions, short pulse durations are effective, because most pigmented lesions seen with photoaging are located superficially in the epidermis (Figure 27-2). Q-switched lasers (see Chapter 19 for a definition), which include 532 nm, ruby (694 nm), alexandrite (755 nm), and Nd:YAG (1064 nm) lasers, have very short pulse durations—in the nanosecond range—and are highly effective for the reduction of unwanted pigmentation.





Patient Expectations


Photorejuvenation of benign pigmented and vascular lesions may be performed on virtually any body region where photodamage is present. The face, neck, chest, and hands are some of the most commonly treated areas. Noticeable results are evident with a single treatment in properly selected candidates, but typically a series of three to five IPL treatments is required for dramatic improvements.4 Treatment with lasers may require a fewer number of treatments than with IPL devices. Larger red facial vessels, which have more chromophore target, usually respond more dramatically than smaller lacy red vessels or diffuse erythema. Discreet lesions such as cherry angiomas typically resolve with no recurrence after one or two treatments.








Anatomy


Benign pigmented lesions, such as lentigines, and benign vascular lesions, such as telangiectasias, are some of the most common lesions evident in photodamaged skin. Figure 27-2 shows the relative location of these lesions in the skin, with lentigines in the epidermis and telangiectasias in the dermis.


Telangiectasias are these cutaneous vessels that range in size from 0.1 to 1.0 mm. The three main types linear, arborizing and spider, are shown in Figure 27-3. Telangiectasias that arise from dilated arterioles are bright red with small diameters; those from venules are bluish in color with larger diameters; and those from capillaries are fine lacy red vessels or appear as background erythema to the naked eye.12 Red facial telangiectasias seen with photoaging are commonly located in the midface on the nasal ala and dorsum of the nose and cheeks. Telangiectasias may also be associated with clinical conditions such as rosacea, genetic syndromes, and collagen vascular diseases (Box 27-1).




Solar lentigines are small brown macules that increase in size and number with chronic sun exposure and are typically located around the periphery of the face (see Figure 27-8A later in the chapter). Postinflammatory hyperpigmentation can be seen in susceptible individuals, typically darker skin types (Fitzpatrick IV through VI), as brown macules arising at sites of previously inflamed acne lesions or sites of wound healing (see Figure 24-6A in Chapter 24, Skin Care Products). Melasma presents as hyperpigmented reticulated patches and brown macules, typically on the cheekbones, upper lip, forehead, and chin (see Figure 27-13A later in this chapter). It is frequently observed following a change in female hormonal status such as during pregnancy (chloasma) or after initiating use of oral contraceptives.


Cutaneous pigmented lesions may be located in the epidermis, dermis, or in both. Solar lentigines and ephelides (freckles) are located in the epidermis. Postinflammatory hyperpigmentation and melasma may be located in any of these levels. A Wood’s lamp can be used to determine the depth of melanin pigmentation in the skin.13 Epidermal pigmentation appears darker with more contrast against the background skin under Wood’s lamp illumination, whereas dermal pigmentation has less contrast.




Procedure Preparation



1. Perform an aesthetic consultation and review the patient’s medical history (see Chapter 19, Aesthetic Principles and Consultation) including hormonally induced hyperpigmentation, history of postinflammatory hyperpigmentation or abnormal scarring; medications that may worsen hyperpigmentation or erythema such as oral estrogen containing hormones or topical steroids; and any previous methods for treating photodamage and success.


3. Obtain informed consent (see Chapter 19; also see Appendix A for an informed consent form and patient information handout titled Photorejuvenation Treatments).



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Mar 12, 2016 | Posted by in General Surgery | Comments Off on Photorejuvenation with Lasers

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