Laser Hair Removal Techniques Flashcards
6 cards from real CLS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Laser Hair Removal Techniques flashcards as text
Which principle underlies the effectiveness of laser hair removal?
Answer: Selective photothermolysis targeting melanin in the hair follicle
Selective photothermolysis uses a wavelength selectively absorbed by the target chromophore (melanin in the hair shaft and follicle), a pulse duration shorter than or equal to the thermal relaxation time of the follicle, and sufficient fluence to thermally destroy the follicle while sparing surrounding tissue.
Why is laser hair removal generally less effective in patients with light blonde, red, or white hair?
Answer: Light hair has minimal melanin, the target chromophore, resulting in insufficient light absorption
Melanin is the primary chromophore targeted in laser hair removal. Blonde, red, and white hairs contain little to no eumelanin, so they do not absorb sufficient laser energy to generate the heat needed to thermally damage the follicle matrix and bulge. These hair colors are poor candidates for conventional laser hair removal.
Which laser wavelength is most appropriate for hair removal in patients with Fitzpatrick skin types V–VI to minimize epidermal melanin damage?
Answer: 1064 nm (Nd:YAG)
The 1064 nm Nd:YAG laser is preferred for dark skin types because melanin absorption is relatively low at this wavelength compared to shorter wavelengths. This allows the beam to penetrate deeper with less epidermal absorption, reducing the risk of epidermal burns and post-inflammatory hyperpigmentation in highly pigmented skin.
What is the approximate thermal relaxation time (TRT) of a terminal hair follicle, which guides selection of appropriate pulse duration?
Answer: 10–100 milliseconds
The thermal relaxation time of a terminal hair follicle is approximately 10–100 milliseconds, depending on follicle diameter. Laser pulse durations within this range allow selective heating of the follicle. Pulses longer than the TRT allow heat to diffuse to surrounding tissue, increasing side effects; shorter pulses may be subtherapeutic.
During a laser hair removal session, a patient with a tan reports sunbathing two days prior. What is the most appropriate course of action?
Answer: Postpone treatment until the tan fades (typically 4–6 weeks), then reassess and adjust parameters
A recent tan significantly increases epidermal melanin, reducing the contrast between skin and hair follicle and increasing the risk of epidermal burns, blistering, and post-inflammatory hyperpigmentation. Treatment should be postponed until the tan has fully faded and the patient's baseline skin type is used for parameter selection.
What role does an integrated cooling system (e.g., cryogen spray, contact cooling, or air cooling) serve during laser hair removal?
Answer: It protects the epidermis from thermal injury while allowing therapeutic temperatures to reach the target follicle
Epidermal cooling reduces the temperature rise in the epidermis by removing heat before, during, or after the laser pulse. This protective effect creates a thermal gradient that allows higher fluences to be used safely, improving therapeutic efficacy at the follicle while maintaining epidermal integrity.