Ablative Versus Non-Ablative Lasers (For Professionals)

Introduction

-ablative lasers (work by photocoagulation) or non-ablative lasers (work by photovaporisation)?

-fractional lasers use the principle of fractional photothermolysis (concept introduced by Rox Anderson): small holes are created in the skin which stimulate deep in the dermis neocollagenesis.

-fractional lasers work deeper than classical lasers: 600-1000 microns.

-3 variables in the classification of ablative lasers (including micro-ablative (fractional) or ablative lasers:

• deepness: is all the greater than the fluency increases.
• wavelength

1. ERYAG 2940: acts more superficially.
2. fraxel 1550: heat distributed in “drilling holes”(thermal cylinders projecting vertically deep into the skin).
3. conversely ablative CO2 lasers (10600nm) generate an extensive area of heat.

• Heat to thermal-ablation ratio: the degree of damage diminishes progressively as the distance to the centre of the cylinder increases. Actually, there is only heat as the distance is far enough and no tissue damage is done.

-stacking: with this method we can go deeper by diminishing the thermal effects including the unwanted ones: the same total energy is delivered by applying in many passes a smaller amount of energy on the area to be treated.

How to use

1. non-ablative lasers:

• topical anesthesia one hour before the treatment session.
• minimum of four 4 treatment sessions
• unwanted side-effects following the treatment:

1. erythema
2. edema
3. crusts
4. transitory hyperpigmentation
5. …non-exhaustive list

2. ablative lasers:

• topical anesthesia or more (intralesional) 90 minutes before the treatment session.
• one treatment session enough, although sometimes 3 or 4 are necessary.
• same side effects than non-ablative lasers but with more important intensity.

Comparison for common indications of treatment

1. Sun induced skin aging

• non-ablative lasers: is more effective on thin skin and the effect is obtained more progressive.
• ablative lasers:

1. works at a dose of 30W, deepness 500um, pulse duration 1.5ms.
2. many passes in a same treatment sessions are sometimes necessary (stacking).

2. Acne scars

• non-ablative lasers: feeling of the presenter: more useful than ablative lasers and that would be explained by a thermal effect.
• ablative lasers: works very well but side effects more frequent and intense.

3. Scars in general

• non-ablative lasers: especially effective for hypochromia ans texture
• ablative lasers: useful in the treatment of keloids at the following dosage parameters: 30W, 800microns, 2ms

4.    Other indications of non-ablative lasers.

• actinic porokeratosis
• minocycline induced pigmentation
• red striae
• granuloma annulare
• poïkiloderma of Civatte (erythrosis colli)
• melasma: ineffective

4.    Other indications for ablative lasers:

• striae
• ILVEN (Inflammatory Linear Verrucous Epidermal Nevus)

Complications (additionally to those already mentioned):

Note: A antiherpetic prophylaxis is anyways necessary for both types of lasers.

• non-ablative lasers:

1. Post-inflammatory hyperpigmentation
2. acne-like folliculitis
3. herpes simplex infection
4. no scarring or permanent dyschromia has been described to this date.

• ablative lasers:

1. Post-inflammatory hyperpigmentation
2. infection (herpes simplex)(more impressive than non-ablative lasers and also appears with prophylaxis)
3. permanent scarring (neck, inferior eyelids)
4. keratoacanthoma (rare)

Conclusion: its all a matter of balancing the risks and rewards.

• additionally concerning costs:

1. non-ablative lasers : expensive (because many treatment sessions are needed).
2. ablative lasers: less expensive (because few, sometimes even one treatment sessions are needed).

• both are effective but the risk to reward ratio is not the same for both lasers.
• Can we combine both types of lasers?: read the article of Bass et al, ASMLS 2009.

Source of information (French): Controverses au sujet du laser (Le Pillouer-Prost A), Journées dermatologiques de Paris 2009

Source of information: here