Lasers Flashcards
After laser removal of an elaborate multi-color tattoo, a patient has residual green ink remaining. Which of the following is the most appropriate treatment for this residual pigment?
A) Carbon dioxide laser
B) Intense pulsed light
C) Long pulse Nd:YAG (1064-nm) laser
D) Q-switched alexandrite (755-nm) laser
E) 70% Trichloroacetic acid peel
The correct response is Option D.
Green tattoo ink responds effectively to treatment with a 755-nm Q-switched alexandrite laser. As of 2013, a picosecond-domain alexandrite laser became commercially available, giving 75% clearance of green pigment in just one to two treatments in fair-skinned patients. Alternatively, ruby lasers, with a 694-nm wavelength, can be used.
The 1064-nm wavelength is very effective for black and other dark colors when a Q-switched or picosecond machine is used. Typically, this wavelength is less effective for green, with this color commonly being left behind after completion of a 1064-nm treatment series.
The long-pulse Nd:YAG is used for hair removal and varicose veins. It does not have the short pulse width required for effective tattoo removal. Similarly, intense pulsed light (IPL), even when filtered to the correct wavelength, doesn’t give the short pulse width required for tattoo removal. Long-pulse laser or IPL pulses in the millisecond domain usually result in incomplete tattoo clearance, thermal damage to surrounding tissues, and scarring.
Trichloroacetic acid (TCA) peels are not pigment-specific. They have become popular with the do-it-yourself patient population, with unregulated sales over the Internet, leading to reports of hypertrophic scarring and chemical burns requiring formal excision and skin grafting. A TCA peel is not recommended as a tattoo treatment, even in the more commonly used concentrations of 30 to 40%, which are used for facial resurfacing.
Carbon dioxide laser is not effective at targeting tattoo pigment.
2017
A 55-year-old woman with moderate sun damage to facial skin and facial wrinkles comes to the office for laser skin resurfacing. Which of the following is the most appropriate management regarding respiratory protection from the laser smoke plume?
A) High-efficiency smoke evacuator placed 20 to 25 cm away from the site of the laser plume
B) High-efficiency smoke evacuator placed within 1 to 2 cm of the smoke plume
C) Standard surgical mask alone
D) Standard wall suction
E) No specialized equipment or protection is necessary
The correct response is Option B.
Along with ocular hazards and fire hazards, laser smoke plume is a significant occupational hazard, which is often ignored when lasers are used. There are numerous substances, some carcinogenic and mutagenic, released during laser pyrolysis of tissue. Viable skin bacteria, including coagulase-negative Staphylococcus, Corynebacterium, and Neisseria, have been recovered from the laser plume following laser skin resurfacing. In addition, intact viral DNA, particularly of human papillomavirus, has been isolated from carbon dioxide laser plume. Most surgical masks only filter particles that are 5 microns in diameter or larger; however, 77% of particles in the laser plume are 1 micron or smaller. Therefore, well-fitted high-filtration or laser masks should be used instead of standard surgical masks. A high-efficiency smoke evacuator should also be used, but it needs to be within 1 to 2 cm of the laser smoke plume source. The effectiveness of the smoke evacuator is decreased from 99 to 50% as the distance from the laser-treated site is increased from 1 to 2 cm, so 20 to 25 cm away is ineffective.
2015
Which of the following is most effective in decreasing the risk of fire when using a carbon dioxide laser for facial resurfacing?
A) Clamp the laser cord to surgical drapes
B) Intubate laser patients to prevent oxygen accumulation on the field
C) Provide supplemental oxygen with a nasopharyngeal cannula
D) Use conscious sedation, nerve blocks, and no supplemental oxygen
E) Use foot pedals only for activating the laser
The correct response is Option D.
Carbon dioxide laser treatments can cause operating room fires. Several papers have shown that a nasopharyngeal oxygen delivery can decrease oxygen levels in the operative field when it is required, but the best way to decrease the level of oxygen on the field is not to use it. Foot pedals can be accidentally activated and should be avoided. Clamping the laser cord can damage the fibers and ignite the laser fiber sheath. Laser skin surfacing can be accomplished without intubation.
2015
A 30-year-old woman of Nordic heritage is interested in laser hair removal of “peach fuzz” on the upper lip. She has Fitzpatrick Type I skin and is very fair, with light blonde hair and blue eyes. Which of the following is the most appropriate technique for hair removal for this patient?
A) Alexandrite laser (755 nm)
B) Electrolysis
C) Intense pulsed-light
D) Long-pulse ruby laser (694 nm)
E) Nd:YAG laser (1064 nm)
The correct response is Option B.
Laser hair removal targets the melanin in the hair follicle. It is not useful in fair-haired patients who have low levels of melanin in their hair follicles.
Although all the devices listed here have been employed for hair reduction, only electrolysis would be likely to work in this patient.
2020
A 27-year-old woman presents with a multicolored decorative tattoo on her leg. She is interested in laser tattoo removal. On physical examination, over 80% of her tattoo has red and orange colors. Which of the following laser treatments would be most effective on the orange and red areas?
A) 755-nm Q-switched alexandrite
B) 532-nm Q-switched Nd:YAG
C) 1064-nm Q-switched Nd:YAG
D) 694-nm Q-switched ruby
The correct response is Option B.
Successful tattoo removal can be performed using different types of laser wavelengths. The 532-nm Q-switched Nd:YAG would be used for targeting red, yellow, and orange color tattoos. Black pigments can be effectively removed with Q-switched Ruby 694-nm, 755-nm Alexandrite, or 1064-nm Nd:YAG lasers. Purple ink responds best to the Q-switched 694-nm ruby laser and green ink best removed with the Q-switched 755-nm Alexandrite laser. The Q-switched Ruby 694 nm laser creates a red light that is highly absorbed by green, blue, and dark tattoo pigments.
2021
A 58-year-old woman with a history of rosacea is scheduled to undergo Er:YAG laser resurfacing to improve the appearance of perioral rhytids. When compared with a carbon dioxide laser, for which of the following does the Er:YAG laser have a greater affinity?
A) Hair follicle
B) Hemoglobin
C) Melanin
D) Papillary dermis
E) Water
The correct response is Option E.
Use of nonsurgical skin rejuvenation has increased exponentially over the past 20 years, with over 4.6 million cases performed annually. This increase has led to expansion of different types of devices for resurfacing. The use of lasers for facial resurfacing has been discussed since the 1980s, initially with carbon dioxide lasers and then with erbium-doped yttrium aluminium garnet (Er:YAG) lasers in the late 1990s. Ablative laser treatments have been used to target actinic skin damage and moderate to heavy rhytides.
Lasers work by means of a wavelength of light being absorbed by specific targets (chromophores) in the tissue, causing thermal damage. The targeted chromophore absorbs energy, which is converted to heat. Tissues that are heated to 60° to 70°C (140°F to 158°F) coagulate; above 100°C (212°F), vaporization occurs. The carbon dioxide laser has a wavelength of 10,600 nm with a target chromophore of water. In the mid 1990s, the ability to deliver increasing power over shorter amounts of time allowed temperatures to be reached that would allow ablation of the epidermis. However, even with ablation there was a zone of coagulation surrounding the ablation that ranged between 70 and 120 ?m. The Er:YAG laser has a wavelength of 2940 nm. The peak absorption of water is nearly 2900 nm, which means that an Er:YAG laser has an absorption 12 - to 16-fold greater than carbon dioxide laser. Because of this unique feature, the ablation threshold of Er:YAG is only 1 J/cm2 compared with the carbon dioxide laser’s ablation threshold of 5 J/cm2. The clinical relevance is that a much higher percentage of targeted tissue is ablated rather than heated, so that the resultant surrounding coagulation zone is only 5 to 20 ?m of tissue.
It is a common mischaracterization of full-field resurfacing options to state that “erbium is more superficial than carbon dioxide.” This is only true for a single pulse and equivalent energies, as the erbium wavelength is rapidly absorbed in water at a rate 11 to 16 times higher than carbon dioxide. However, such a statement is contrary to the fact, as erbium allows ablation of the dermis and the epidermis, unlike carbon dioxide, which can only ablate epidermis. Erbium can easily ablate the dermis on successive pulses until the skin, muscle, and even bone can be totally obliterated. Carbon dioxide can only affect deep tissue by stacking pulses and creating “bulk heat” that melts the tissue rather than ablating, and is both imprecise and dangerous.
Erbium provides a controlled depth of ablation with a minimal underlying thermal zone of coagulation. This decrease in thermal injury leads to a faster recovery following erbium laser ablation compared with carbon dioxide laser. The smaller coagulative zone results in a lower rate of hypopigmentation and allows for a more controlled depth with each pass. Carbon dioxide lasers can have variable depth of penetration, especially after the first pass when the dermis is exposed, and the residual thermal injury creates a “char,” which becomes thicker with each pass, making penetration increasingly difficult.
2021
A 54-year-old man with Fitzpatrick type II skin is scheduled to undergo photoaging treatment with a carbon dioxide fractional laser. Which of the following measures is most likely to decrease this patient’s risk of hypertrophic scarring?
A) Decreasing fluences
B) Heat stacking
C) Increasing surface area coverage
D) Treating the neck skin
E) Using multiple laser passes
The correct response is Option A.
Fractional laser resurfacing of photo-damaged or acne-scarred skin has supplanted traditional carbon dioxide ablative laser devices while diminishing the incidence of adverse effects and effecting a more rapid recovery. However, hypertrophic scarring (HTS) is a noteworthy complication that requires the utilization of preventive measures to minimize its occurrence. Conservative treatment of the neck is foremost among these measures. Use of lower fluences (energy density, defined as Joules/cm2) treating reduced surface areas, abstinence from heat stacking, and avoiding multiple passes by a carbon dioxide laser all contribute to less incidence of HTS. Patient selection, preoperative education, and preparation for treatment of this complication are appropriate adjunctive measures as well.
2021
A healthy 48-year-old woman comes to the office for consultation regarding laser resurfacing of fine facial wrinkles in the perioral region. Her skin color is light brown and she states that she rarely gets sunburned (Fitzpatrick Type IV). Examination shows rhytides in the perioral region, on the forehead, and in the lateral canthal region. Compared with a patient who has a lighter skin color (Fitzpatrick Type I-III), which of the following is this patient at increased risk for after laser resurfacing in the perioral region?
A) Freckles
B) Herpetic lesions
C) Hypertrophic scars
D) Post-treatment hyperemia
E) Postinflammatory hyperpigmentation
The correct response is Option E.
Understanding the potential complications after facial resurfacing is important to know, especially those complications that occur in patients with darker skin. Traditionally, the Fitzpatrick Scale is used to assess skin tone and risk for both the development of skin cancer and also response to post-treatment pigmentation issues. Herpetic lesions can develop in individuals with any skin color after laser treatment. While hyperemia can develop in any patient after laser resurfacing, post-inflammatory hyperpigmentation is of greatest concern in those with darker skin color, especially in an individual like the one described, who has a Fitzpatrick Type IV skin type. While there are different ways to mitigate the issue of pigmentation both before and after treatment, it is a risk factor that should be discussed with patients undergoing skin resurfacing, especially in darker skin individuals. Laser therapy has been used to treat hypertrophic scars and freckles.
2021
A 21-year-old woman with Fitzpatrick Type V skin presents for evaluation of acne scarring. Treatment with a fractional nonablative laser is planned. Which of the following lasers is most appropriate to treat acne in this patient?
A) Carbon dioxide (10,600 nm)
B) Erbium-doped fiber (1550 nm)
C) Erbium:YAG (2940 nm)
D) Erbium:YSGG (2790 nm)
The correct response is Option B.
Nonablative fractional lasers are commonly used for acne scar resurfacing in darker skin types. Nonablative lasers work by denaturation of dermal collagen with subsequent remodeling, without any vaporization or damage to the epidermis.
Erbium-doped fiber laser (1550 nm) is a nonablative laser while Erbium:YAG (2940 nm), carbon dioxide (10,600 nm), and Erbium:YSGG (2790 nm) are ablative lasers.
2022
A 58-year-old woman plans to undergo Er:YAG laser resurfacing (2940 nm) to improve the appearance of perioral rhytides. The procedure targets which of the following?
A) Collagen
B) Elastin
C) Hemoglobin
D) Melanin
E) Water
The correct response is Option E.
Use of nonsurgical skin rejuvenation has increased exponentially over the past 20 years, with over 4.6 million cases performed annually. This increase has led to expansion of different types of devices for resurfacing. The use of lasers for facial resurfacing has been discussed since the 1980s, initially with carbon dioxide lasers and then with erbium-doped yttrium aluminium garnet (Er:YAG) lasers in the late 1990s. Ablative laser treatments have been used to target actinic skin damage and moderate to heavy rhytides.
Lasers work by means of a wavelength of light being absorbed by specific targets (chromophores) in the tissue, causing thermal damage. The targeted chromophore absorbs energy, which is converted to heat. The Er:YAG laser has a wavelength of 2940 nm. The peak absorption of water is nearly 2900 nm, which means that an Er:YAG laser has an absorption 12- to 16-fold greater than carbon dioxide laser. Targeting hemoglobin would not be appropriate since this will not lead to rejuvenation of perioral rhytides. The treatment of melanin is not the correct target since this would only lead to hypopigmentation or absorb the laser wavelength and lead to a possible burn. Collagen and elastin are essential elements of maintaining a youthful dermis; these dermal proteins are not the target of lasers, but rather induced by the trauma occurring from the laser itself.
2022
An 18-year-old woman with Fitzpatrick type IV skin presents for carbon dioxide laser treatment for hypertrophic scarring 1 year after sustaining facial burns. Two weeks after the first session, hypopigmentation is noted in the laser-treated areas. Which of the following adjustments to the laser setting is most likely to prevent further hypopigmentation from occurring after the next session?
A) Decreasing the dwell time
B) Decreasing the spot size
C) Increasing the dwell time
D) Increasing the energy
E) Increasing the spot size
The correct response is Option A.
Patients classified as higher Fitzpatrick types have a higher risk for hypopigmentation after carbon dioxide laser therapy. For example, punctate hypopigmentation has been found in up to 35% of facial burn patients presenting 2 months after being treated with fractionated carbon dioxide laser therapy. To decrease the risk for further hypopigmentation, the dwell time needs to be decreased. Increasing the dwell time prolongs the time of exposure, increasing the risk for hypopigmentation. Increasing or decreasing the spot size only increases or decreases the surface area treated. Increasing the energy would also increase the risk for hypopigmentation.
2022
A patient with Fitzpatrick Type V skin presents for removal of a 5-year-old tattoo on his forearm that is primarily black in color. The most appropriate laser for removal of the pigment in this patient uses which of the following wavelengths?
A) 532 nm
B) 694 nm
C) 755 nm
D) 1064 nm
E) 10,600 nm
The correct response is Option D.
2023
A 56-year-old woman is scheduled for carbon dioxide laser treatment of facial rhytides. Which of the following is the primary chromophore for a carbon dioxide laser?
A) Deoxyhemoglobin
B ) Melanin
C) Methemoglobin
D) Oxyhemoglobin
E) Water
The correct response is Option E.
A carbon dioxide laser emits light at a wavelength of 10,600 nm that is absorbed strongly by water.
The classic target chromophore for vascular lesions has been oxyhemoglobin, which has the greatest absorption peaks at 418 nm, 542 nm, and 577 nm.
Venous lesions may benefit from wavelengths of light that target deoxyhemoglobin. The alexandrite laser at 755 nm is close to a deoxyhemoglobin absorption peak and has been used for refractory or hypertrophic port-wine stains, venocapillary malformations, and venous lakes.
Methemoglobin absorption (which occurs after 585-nm or 595-nm treatment at or above 5 J/cm2 ) has been recognized as another potential target chromophore.
Since melanin absorbs light at a wide range of wavelengths, from 250 nm to 1200 nm, almost any laser with sufficient power causing thermal denaturation can be used to remove benign pigmented lesions of the epidermis. Eumelanin, the primary chromophore in the epidermis and darkly pigmented hair follicles, has a broad absorption spectrum spanning from ultraviolet light to the near infrared region.
2023
A 54-year-old woman with Fitzpatrick Type III skin plans to undergo Er:YAG laser (2940 nm) resurfacing to improve the appearance of periorbital rhytides. Prior to treatment, the plastic surgeon recommends a topical agent that inhibits enzymatic conversion of tyrosine to dihydroxyphenylalanine. Which of the following agents did the surgeon most likely discuss?
A) Brimonidine
B) Fluocinolone acetonide
C) Hydroquinone
D) Tretinoin
E) Zinc oxide
The correct response is Option C.
Use of nonsurgical skin rejuvenation has increased exponentially over the past 20 years, with over 4.6 million cases performed annually. This increase has led to expansion of different types of devices for resurfacing. The use of lasers for facial resurfacing has been discussed since the 1980s, initially with carbon dioxide lasers and then with erbium-doped yttrium aluminium garnet (Er:YAG) lasers in the late 1990s. Ablative laser treatments have been used to target actinic skin damage and moderate to heavy rhytides.
Post-inflammatory hyperpigmentation (PIH) is a common sequela of laser resurfacing procedures. Pretreatment with various topical agents can optimize the skin, decreasing the risk for this well-known adverse event. Hydroquinone decreases melanin production by enzymatically inhibiting the conversion of tyrosine to dihydroxyphenylalanine.
Tretinoin promotes cornified cell detachment and enhances shedding. It also increases mitotic activity, thereby increasing loosely adherent corneocytes turnover. Tranexamic acid is a synthetic derivative of the amino acid lysine and binds the five lysine binding sites on plasminogen. This inhibits plasmin formation and displaces plasminogen from the fibrin surface. In melasma, the hypothesized mechanism of action of tranexamic acid includes the shrinkage of dermal vasculature and decreased melanin synthesis by altering the interaction of keratinocytes and melanocytes and decreasing tyrosinase activity. Fluocinolone acetonide is a potent corticosteroid that is often used in conjunction with tretinoin and hydroquinone to treat pre-existing PIH and/or for pretreatment of the skin prior to laser resurfacing. By itself, fluocinolone does not have the aforementioned mechanism of action. Brimonidine gel, originally approved for the treatment of facial rosacea, causes direct vasoconstriction. This alpha-adrenergic receptor agonist is often used in conjunction with topical steroids to help decrease the risk for PIH. Zinc oxide is a physical barrier sunscreen.
2023
