The third Q-switched laser developed for the treatment of tattoos, the Q-switched alexandrite laser, has a wavelength of 755 nm, a pulse width of 100 nanoseconds (50-ns pulse width is available in newer models), and a repetition rate of 1 Hz. The 3-mm diameter beam is delivered via a fiberoptic system or an articulated arm. Reflectance studies at 755 nm suggest excellent absorption by black pigment, good absorption by blue and green, and poor absorption by red pigment, as confirmed by preliminary studies performed on tattooed Yucatan minipigs. One treatment session provided excellent results in removal of black ink, good results with blue and green, and poor results with red ink. Efficacy was fluence related.
Unlike previous reports concerning the QSRL and Q-switched Nd:YAG laser, histologic clearing correlated with clinical clearing. Similar to reports of the other Q-switched lasers, fragmentation of tattoo pigment was followed by macrophage engulfment and gradual clearing of the pigment but with clinically clear tattoos devoid of ink at histologic examination. Interestingly, tattoo pigment was progressively altered during this process, initially appearing as sharp-bordered grains of pigment in clumps and assuming a progressively amorphous form and lighter color within the macrophages. No clinical or histologic reaction in collagen, scarring, or atrophy was seen in laser-treated sites.
Fluence and Treatment Sessions
The Q-switched alexandrite laser was initially studied with 30 tattoos using fluences of 4.5-8 J/cm2. Test sites using 3 fluences up to 6 J/cm2 were evaluated at 4 weeks. The appropriate fluence was then selected, and treatment was begun. A second test was performed when none of the previous fluences revealed significant lightening. Fluences of 6 J/cm2 or higher were used once the tattoo had lightened by 20-50%. Approximately 25% clearance required 1.7 treatments, 50% clearance required 2.8 treatments, 75% clearance required 5 treatments, 90% clearance required 6.4 treatments, and total clearance required 10.4 treatments (range, 4-16). Professional tattoos cleared as well as amateur tattoos, although the latter responded more rapidly, requiring approximately 3 fewer treatments to reach complete clearance; however, some professional tattoos also responded rapidly.
Transient hypopigmentation is common (occurs in 50% of patients), but it is often not apparent until after 5-7 treatment sessions and usually resolves gradually over 1-12 months. As with the other Q-switched lasers, hyperpigmentation is more dependent on skin type and clears with hydroquinone and sunscreen. Transient surface textural changes, noted in about 10% of patients, usually resolve.
On laser impact, the immediate flash of white light from the tattoo is followed by epidermal whitening and slight edema, as seen with both the QSRL and the Q-switched Nd:YAG laser. When higher fluences are used, purpura is noticed, and pinpoint bleeding may occur. Tissue splatter and erosions were not seen at any of the fluences used with the 100-nanosecond pulse width; however, the shorter 50-nanosecond pulse width, which reportedly increases tattoo clearance, is associated with more epidermal debris. Therefore, increasing the fluence up to the maximum available without causing pinpoint bleeding may prevent the problems of working in a bloody field and possible tissue trauma. In summary, the Q-switched alexandrite laser is effective and safe for removing blue, black, and green tattoo pigment. Approximately 4-10 treatments performed at 1- to 2-month intervals usually clear the tattoo without scarring; however, one half of patients develop transient hypopigmentation.
510-mm, 300-nanosecond Candela Pigmented Lesion Dye Laser
The flashlamp-pulsed laser (510 nm, pulse width of 300 ± 100 ns) was developed as a companion to the Q-switched alexandrite laser to treat epidermal melanocytic lesions. This wavelength is also well absorbed by red pigment, and the pulse width is short enough to fragment ink granules. Successful clearing without scarring usually occurs in 3-7 treatments performed at 1-month intervals using 3-3.75 J/cm2. Purple, orange, and yellow pigments require an average of 5 treatments for complete ink removal. No hypopigmentation, textural change, or scarring is noted. Histologically, fragmentation of red pigment particles is observed, followed by macrophage engulfment. In addition, because of the epidermal absorption of this laser, transepidermal ink loss occurs.