The commonest acquired pigmented spots encountered in the aesthetic consultations are freckles, solar lentigines, and melasma. Café-au-lait spots become more apparent in early childhood.

All these pigmented problems can be aggravated by sun exposure and so it is important to apply sun protection while seeking treatment to remove them. As mentioned before, melasma is notoriously difficulty to get treated by laser and some doctors would avoid to treat it, because of the potential complications.

What Lasers Are Used?

The lasers used in this aspect must have wavelengths that are well absorbed by the melanin pigment. The commonly used include 510nm, 532nm, 755nm and 1064nm. They are all excellent in removing freckles and solar lentigines.

The 510nm is a pulsed dye laser, while 532nm, 1064nm and 755nm are solid-state lasers, and are opearated in two available but separate modes: the Q-switched (QS) mode and the long-pulsed (LP) mode.

Q-switched (QS) mode

It allows the laser energy to go through the filter in an ultra-short time (nano second). The result is a more explosive nature, which can thermally and mechanically shatter the pigment into very small fragments, and removed by our own system.

However, it has a small spot size of 3 - 4 mm, and so can target only individual spots, one at a time. The result is, there may be uneven colour between treated spots and the surrounding non-treated skin. It also causes a lot of redness and swelling after treatment, which may take up to a week to resolve. Because of these factors, you cannot have the whole face treated with this laser.

All 3 wavelengths have a QS mode: QS 532nm, QS 755nm, Qs 1064nm.

Long-pulsed (LP) mode

It is a newer version. The laser energy is delivered through a longer period (milli second), and the pigment is burnt by this prolonged heating.

It has a much larger spot size, and can be used to cover a large area in minutes. It is also more gentle in that it causes a lot less redness and swelling, typically 1/3 of that caused by QS lasers, and is apparent only on the pigmented spots. The downtime is a little shorter, by 1 –2 days. Because of these, it is very easy to use on the whole face, taking pigmented spots off, as well as lightening the skin colour for the rest of the face.

Only LP 755nm is popularly used for this. LP 1064nm is relatively less absorbed by melanin and is mainly used for laser hair removal.

Treatment examples:

QS 755nm

Note the temporary paler colour in the treated areas 1 week later, compared to surrounding skin. Last picture after 2 months.

LP 755nm

Mild Freckles

Moderate Freckles & Solar Lentigines

Mixed Pigmented Spots



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