Author: Anoma Ranaweer B.V.Sc; PhD (Clinical Biochemistry, University of Liverpool, UK); Chief Editor: Dr Amanda Oakley, Dermatologist, Hamilton New Zealand, January 2014.
What is a laser?
A LASER (light amplification by stimulated emission of radiation) works by emitting a wavelength of high energy light, which when focused on a certain skin condition will create heat and destroy diseased cells. Wavelength is measured in nanometres (nm).
Various kinds of lasers are available for use in skin surgery. They are differentiated by the medium that produces the laser beam. Each of the different types of lasers has a specific range of utility, depending on its wavelength and penetration. The medium amplifies the light of a particular wavelength as it passes through it. This results in the release of a photon of light as it returns to a stable state.
The duration of the light pulses affects the laser’s clinical applications in skin surgery.
What is an alexandrite laser?
An alexandrite laser is one that uses an alexandrite crystal is used as the laser source or medium. The alexandrite laser produces a specific wavelength of light in the infrared spectrum (755 nm). It is considered a red light laser.
Alexandrite lasers are also available in the Q-switched mode. Q-switching refers to the technique of making the laser produce a high-intensity beam in very short pulses.
How does an alexandrite laser work?
The wavelength of high energy light emitted by the laser is converted to heat energy and this damages the specific target area. Thus alexandrite lasers work by a process of photothermolysis: this means using light (photo) to heat (thermo) a selected area for destruction (lysis).
Alexandrite lasers cause very precise tissue destruction of the lesion and leave the tissue in the surrounding area undamaged.
What is an alexandrite laser used for?
The US Food and Drug Administration (FDA) has approved a range of alexandrite laser machines emitting infrared light (wavelength 755 nm) for various skin disorders. These include Ta2 Eraser™ (Light Age, California, USA), Apogee® (Cynosure, Massachusetts, USA) and Accolade™ (Cynosure, MA, USA), Individual machines may be specially designed to focus on specific skin problems.
The following skin disorders can be treated with Alexandrite laser beams.
Vascular lesions
- Spider and thread veins in the face and legs, some vascular birthmarks (capillary vascular malformations).
- Light pulses target red pigment (haemoglobin).
Pigmented lesions
- Age spots (solar lentigines), freckles, flat pigmented birthmarks (congenital melanocytic naevi), naevus of Ota and acquired dermal melanocytosis.
- Light pulses target melanin at variable depth on or in the skin.
Hair removal
- Light pulses target the hair follicle causing the hair to fall out and minimising further growth.
- May be used for hair removal in any location including underarms, bikini line, face, neck, back, chest and legs.
- Generally ineffective for light coloured hair, but useful for treating dark hair in patients of Fitzpatrick types I to III, and perhaps light-coloured type IV skin.
- The typical settings employed include pulse durations of 2 to 20 milliseconds and fluences of 10 to 40 J/cm2.
- Extreme caution is recommended in tanned or darker skinned patients, as the laser can also destroy melanin, resulting in white patches of skin.
Tattoo removal
- The use of Q-switched alexandrite lasers has improved the process of tattoo removal and today is considered the standard of care.
- Alexandrite laser treatment is used to remove black, blue and green pigment.
- The laser treatment involves the selective destruction of ink molecules that are then absorbed by macrophages and eliminated.
- The short pulse duration of 50 to 100 nanoseconds allows laser energy to be confined to the tattoo particle (approximately 0.1 micrometres) more effectively than a longer-pulsed laser.
- Sufficient energy must be delivered during each laser pulse to heat the pigment to fragmentation. Without enough energy in each pulse, there is no pigment fragmentation and no tattoo removal.
- Tattoos that have not been effectively removed by other treatments may respond well to laser therapy, providing prior treatment has not caused excessive scarring or skin damage.
Alexandrite lasers may also be used to improve wrinkles in photo-aged skin.
What does the laser procedure involve?
It is important that the correct diagnosis has been made by the clinician prior to treatment, particularly when pigmented lesions are targeted, to avoid mistreatment of skin cancers such as melanoma.
- The patient must wear eye protection consisting of an opaque covering or goggles throughout the treatment session.
- Treatment consists of placing a handpiece against the surface of the skin and activating the laser. Many patients describe each pulse to feel like the snapping of a rubber band against the skin.
- A topical anaesthetic may be applied to the area but is not usually necessary.
- Skin surface cooling is applied during all hair-removal procedures. Some lasers have built-in cooling devices.
- Immediately following treatment, an ice pack may be applied to soothe the treated area.
- Care should be taken in the first few days following treatment to avoid scrubbing the area, and/or use of abrasive skin cleansers.
- A bandage or patch may help to prevent abrasion of the treated area.
- During the course of treatment, patients should protect the area from sun exposure to reduce the risk of postinflammatory pigmentation.
Are there any side effects of alexandrite laser treatment?
Side effects from alexandrite laser treatment are usually minor and may include:
- Pain during treatment (reduced by contact cooling and if necessary, topical anaesthetic)
- Redness, swelling and itching immediately after the procedure that may last a few days after treatment.
- Rarely, skin pigment may absorb too much light energy and blistering can occur. This settles by itself.
- Changes in skin pigmentation. Sometimes the pigment cells (melanocytes) can be damaged leaving darker (hyperpigmentation) or paler (hypopigmentation) patches of skin. Generally, cosmetic lasers will work better on people with lighter than darker skin tones.
- Bruising affects up to 10% of patients. It usually fades on its own.
- Bacterial infection. Antibiotics may be prescribed to treat or to prevent wound infection.
How many laser treatments can I expect?
Vascular lesions
- Vascular lesions may require multiple treatments. The treatment time depends on the form, size and location of the lesions as well as the skin type.
- Small red vessels can usually be removed in only 1 to 3 sessions and are generally invisible directly after the treatment.
- Several sessions may be necessary to remove more prominent veins and spider veins.
Hair removal
- Laser hair removal needs multiple sessions (3 to 6 sessions or more). The number of sessions depends on the area of the body being treated, skin colour, coarseness of hair, underlying conditions such as polycystic ovaries, and sex.
- Clinicians generally recommend waiting from 3 to 8 weeks between laser sessions for hair removal.
- Depending on the area, the skin will remain completely clean and smooth for around 6 to 8 weeks after treatment; it is time for the next session when fine hairs start to grow again.
Tattoo removal
- The colour of the tattoo and the depth of the pigment influence the duration and the outcome of the laser treatment for tattoo removal.
- Multiple sessions (5 to 20 sessions) spaced at least 7 weeks apart may be required to attain favourable results.
