* Acceptable secondary publication
* This article was published in the Medical Lasers.
* The authors have received approval from the editors of the Medical Lasers and the D&PS.
Considering this, these treatments were performed during the time when the leading trend was to use a high fluence and high cumulative energy. As for the treatment interval, studies report a wide variety of intervals used and it is difficult to estimate an average interval duration. However, another study published by the same authors described a case of hypopigmentation developing after 4 weeks of daily treatments.14
Moreover, the daily treatment of 1,064 nm QS Nd:YAG laser was proposed by some clinicians in 2005.17 Based on these data, one can estimate that about 20-30 treatments could have been given with at most one-week intervals in the early days of laser toning. Although the authors did not provide the information on the treatment techniques as their patients had received the treatment elsewhere7 but considering the trends of the time, a high fluence, high cumulative energy, excessive tissue response and frequent treatments might have been used in laser toning therapy.
If so, what would be the risk of hypopigmentation occurring as a complication of such a treatment method? Chan et al7 examined patients who were referred due to complications and does not provide the total number of patients receiving laser toning. Therefore, the exact incidence of the hypopigmentation could not be identified. But it mentioned that there was “an approximately 10% risk of hypopigmentation from laser toning in Asian patients,” citing other studies that investigated the rate of hypopigmentation.7
Let us take a look at the parameters and techniques used in other studies on laser toning-related hypopigmentation. In 2010, Wattanakrai et al8 reported that 3 (13.6%) out of 22 patients with melasma receiving laser toning developed mottled hypopigmentation. Laser toning was performed using a 1,064 nm QS Nd:YAG laser (MedLite C6, Hoya ConBio, Fremont, CA, USA), with a 6 mm spot size and a fluence of 3.0-3.8 J/cm2.
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The patients received five weekly treatments. When 5-10 treatments were given in addition to the first five treatments, 8 out of 22 patients developed confetti-like hypopigmentation. The authors concluded that laser toning is risky and advised to limit the number of treatment to 5 or less with sufficient intervals in between to prevent hypopigmentation. They also emphasized the importance of closely monitoring the signs of hypopigmentation and if they are found, discontinue treatment immediately. They did not directly attribute hypopigmentation to a high fluence, however, they report having used high fluence levels in their laser toning treatments.
Cho et al9, in 2009, reported that 2 out of 25 Korean patients developed hypopigmentation. The 1,064 nm QS Nd:YAG laser (MedLite C6, Hoya ConBio, Fremont, CA, USA) was used over the entire face surface (2 passes at a 6 mm spot size and 2.5J/cm2) and the parameters were changed for 2 more passes given only on melasma lesions (4 mm spot size, 4-5J/cm2). The treatment interval was 2 weeks. Judging from the local anesthesia used prior to treatment, they might use a very high fluence.
Another study published in 2011 also reported of similar results.12 This study examined patients who received laser toning in 2008 at a quite high fluence of 2-4J/cm2 over 10 weekly treatments. One out of 23 patients with melasma developed hypopigmentation.
-To be continued
