CLS Laser Hair Removal Techniques

Question 1

Which principle underlies the effectiveness of laser hair removal?

Accepted Answer

Selective photothermolysis targeting melanin in the hair follicle

Answer

Photobiomodulation of follicular stem cells

Answer

Non-selective thermal damage to the entire dermis

Answer

Photochemical destruction of sebaceous glands adjacent to follicles

Question 2

Why is laser hair removal generally less effective in patients with light blonde, red, or white hair?

Accepted Answer

Light hair has minimal melanin, the target chromophore, resulting in insufficient light absorption

Answer

Light hair contains less keratin, reducing heat generation

Answer

Light hair follicles are located deeper in the dermis

Answer

Light-haired patients have a higher density of eccrine sweat glands that deflect the laser

Question 3

Which laser wavelength is most appropriate for hair removal in patients with Fitzpatrick skin types V–VI to minimize epidermal melanin damage?

Accepted Answer

1064 nm (Nd:YAG)

Answer

532 nm (KTP)

Answer

694 nm (Ruby)

Answer

755 nm (Alexandrite)

Question 4

What is the approximate thermal relaxation time (TRT) of a terminal hair follicle, which guides selection of appropriate pulse duration?

Accepted Answer

10–100 milliseconds

Answer

1–10 microseconds

Answer

100 milliseconds to 1 second

Answer

1–10 nanoseconds

Question 5

During a laser hair removal session, a patient with a tan reports sunbathing two days prior. What is the most appropriate course of action?

Accepted Answer

Postpone treatment until the tan fades (typically 4–6 weeks), then reassess and adjust parameters

Answer

Proceed with treatment at the standard protocol fluence

Answer

Reduce the fluence by approximately half and use a longer wavelength if possible

Answer

Apply a topical bleaching cream immediately before treatment

Question 6

What role does an integrated cooling system (e.g., cryogen spray, contact cooling, or air cooling) serve during laser hair removal?

Accepted Answer

It protects the epidermis from thermal injury while allowing therapeutic temperatures to reach the target follicle

Answer

It increases the laser's penetration depth by reducing tissue scattering

Answer

It eliminates the need for topical anesthetic by numbing the area

Answer

It reduces the pulse duration needed to achieve follicular damage