Flashcards in Energy-based treatment of the ageing face for skin resurfacing – Ablative and non-ablative lasers & Photodynamic therapy Deck (152):
Regarding photodamage, ablative laser skin resurfacing offers the most substantial clinical improvement.
Regarding photodamage, non-ablative laser resurfacing is associated with several weeks of postoperative recovery.
F True for ablative laser skin resurfacing.
Ablative laser skin resurfacing provides a modest improvement of photodamaged skin with a limited post-treatment recovery period.
F True for non-ablative laser skin resurfacing.
Fractionated laser systems provide the benefits of higher energy treatments with fewer side effects than traditional lasers.
Extrinsic ageing effects are usually limited to the epidermis and upper papillary dermis and are therefore amenable to treatment with laser.
Ablative lasers are selectively absorbed by water and act to vaporise skin in a controlled manner.
Ablative laser resurfacing carries a reduced risk of scarring and pigmentary alteration compared to non-ablative methods.
F Increased risk.
Ablative laser resurfacing can be safely carried out in patients with darker skin types.
F Ideally skin type I or II.
Preoperative use of topical tretinoin, hydroquinone or glycolic acid for several weeks reduces the incidence of postablative laser hyperpigmentation.
Prophylactic antibiotics should be used postablative laser to reduce the possibility of bacterial contamination and overgrowth in the de-epithelialised skin.
F Controversial. Studies haven’t shown any significant change in infection rate.
Pts with a history of herpes labialis should receive prophylactic oral antivirals starting 1 day prior to resurfacing and continuing for 10 days postoperatively.
Ablative resurfacing lasers include: pulsed CO2 (10600nm), pulsed erbium:YAG (2940), and fractionated (10600 and 2940nm)
Using CO2 laser, water-containing tissue is vaporised to a depth of approximately 20-100um, producing a zone of thermal damage ranging from 20 to 150um.
F Vaporisation depth 20-60um.
Using CO2 laser, depth of ablation is directly correlated with number of passes performed and is usually restricted to the epidermis and upper papillary dermis.
Using CO2 laser, stacking of laser pulses doesn’t cause excessive thermal injury.
F Does. Risk of scarring.
Using CO2 laser, an ablative plateau is reached, with less effective tissue ablation and accumulation of thermal injury.
T This effect is due to reduced water content after initial dessication.
With any laser system, complete removal of partially dessicated tissue and avoidance of pulse stacking is paramount to prevention of excessive thermal accumulation.
The objective of ablative laser skin resurfacing is to vaporise tissue to the reticular dermis.
F Papillary dermis.
Limiting the depth of ablative laser penetration to the reticular dermis decreases the risk for scarring and permanent pigmentary alteration.
F Papillary dermis.
For CO2 laser, whether or not previous treatments have been delivered to an area is irrelevant when choosing treatment parameters.
Areas with thinner skin require fewer passes with a CO2 laser.
CO2 laser resurfacing of non-facial areas (eg neck, chest) should be avoided due to the relative paucity of pilosebaceous units in these areas.
CO2 laser resurfacing can offer at least a 50% improvement over baseline in overall skin tone and wrinkle severity.
The most profound effects of CO2 laser resurfacing occur in the epidermis.
F Papillary dermis – elastotic material replaced with normal collagen bundles.
The advantages of CO2 laser skin resurfacing are the excellent tissue contraction, haemostasis, prolonged neocollagenesis and collagen remodelling.
Absolute CI to CO2 laser resurfacing includes active infection or an inflammatory skin condition involving the areas to be treated.
Contraindication to CO2 laser resurfacing includes the use of isotretinoin within the preceding 2 years.
F Preceding 6-12 months.
Contraindication to CO2 laser resurfacing includes a history of keloids.
YAG laser emits a 2940nm wavelength light corresponds to the 3000nm absorption peak of water-
The absorption coefficient of the Er:YAG laser makes it less efficiently absorbed by water-containing tissue compared with the CO2 laser.
F 12-18 times more efficiently absorbed.
The pulse duration for Er:YAG is much shorter than the CO2 laser, resulting in decreased thermal diffusion, less effective haemostasis and increased intraoperative bleeding which hampens deeper dermal treatment.
The amount of collagen contraction is increased with Er:YAG compared to CO2 laser.
F Decreased due to limited skin injury.
Much narrower zones of thermal necrosis are produced with Er:YAG compared to CO2 laser.
There is no distinctive popping sound with Er:YAG laser use compared to CO2 laser.
F Popping sound produced by ejection of dessicated tissue.
With Er:YAG laser, because little tissue necrosis is produced with each pass of the laser, manual removal of dessicated tissue is often unnecessary.
short-pulsed erbium laser fluences used most often range from 30-50um J/cm2, depending on the degree of photodamage and anatomic location.
F 5 to 15 J/cm2.
When lower fluences are used, it is often necessary to perform multiple passes to ablate the entire dermis with Er:YAG laser.
The depth of ablation with the short-pulsed Er:YAG doesn’t diminish with successive passes.
T Because the amount of thermal necrosis is minimal with each pass.
It takes 3-4 times as many passes with the CO2 laser to achieve similar depths of penetration as with one pass of the Er:YAG laser at typical treatment parameters.
F Other way around.
Because more pulses must be used with the Er:YAG laser, there is an increased possibility of uneven tissue penetration.
Areas treated with Er:YAG immediately whiten after treatment and then the white colour quickly fades.
Short-pulsed Er:YAG can be used for superficial or dermal lesions
Short-pulsed Er:YAG tends to have a longer recovery period.
Re-epithelialisation post Er:YAG laser is completed within 8.5 days on average, compared with 5.5 days for multiple-pass CO2 laser procedures.
F Other way around.
Post-operative pain and duration of erythema are reduced after short-pulsed Er:YAG compared to CO2 laser.
Post-op erythema from Er:YAG resolves within 1-2 weeks.
F 3-4 weeks.
Er:YAG is contraindicated in darker skin phototypes.
The major disadvantage of short-pulsed Er:YAG is its limited ability to effect significant collagen shrinkage.
The final result with Er:YAG ablation is typically less impressive compared with CO2 resurfacing for deeper rhytides.
For mild photodamage, Er:YAG only typically produces improvement of about 20%.
Ablative fractional resurfacing devices have the ability to achieve comparable clinical results to non-fractional methods.
Ablative fractional resurfacing devices can keep the majority of the dermis intact, thus allowing quicker recovery periods and an improved safety profile.
Fractional lasers deliver energy through macroscopic zones of thermal injury, leading to coagulation necrosis and resultant new collagen formation.
Annular coagulation of dermal collagen occurs with fractional ablative laser, with increasing fluences resulting in increasing treatment depths.
With fractional ablative laser, the deep dermal ablated zones are surrounded by zones of sparing, which result in quicker recovery compared to non-fractional methods.
Using fractional ablative laser, multiple treatments are required for any noticeable clinical improvement.
F Improvement in texture, dyschromia and mild laxity after one treatment.
Fraxel is a fractionated CO2 laser.
With fractional laser, ablation depth and the residual thermal damage depend on energy density and the number of stacked pulses used.
Fractional and non-fractional laser treatments should never be combined.
Fractional laser ablation requires longer recovery time than other ablative lasers.
F Average 5-7 days.
Temporary bronzing, acneiform eruptions and milia formation can occur after fractional laser ablation.
Results from a single fractional laser ablative treatment are noted 3-6 weeks after the procedure.
F 3-6 months, after collagen remodelling complete.
Ablative fractional laser resurfacing cannot be performed on the neck and chest.
Scarring and pigmentary alteration are potential side effects of ablative fractional laser.
F These have never been reported.
Expected side effects of ablative laser resurfacing include erythema, oedema and pruritus.
Mild complications of ablative laser include extended erythema, milia, acne and contact dermatitis.
Severe complications of ablative laser include hypopigmentation, hypertrophic scarring and ectropion.
Erythema after ablative laser is always mild and resolves quickly.
F Can be intense and may persist for months.
Degree of erythema is unrelated to the depth of ablation and the number of laser passes performed.
F Correlates directly with this.
Underlying rosacea or dermatitis can aggravate the erythema seen post-laser ablation.
Post-operative erythema resolves spontaneously
T May be reduced with the application of topical ascorbic acid
Topical ascorbic acid should be avoided post-laser ablation.
F Can reduce postoperative erythema.
Topical ascorbic acid can be used immediately after laser ablation.
F Should wait at least 4 weeks.
Topical agents such as retinoids, glycolic acid and fragrance-containing or chemical-containing cosmetics and sunscreens should be strictly avoided in the early postoperative period after ablative laser.
Minor side effects of laser resurfacing include milia formation and acne exacerbation.
Milia and acne seen post ablative laser are thought to be due to occlusive dressing and ointments in the postoperative periods, particularly in patients who are prone to acne.
Reactivation of labial HSV post laser ablation is most likely due to thermal tissue damage and epidermal disruption.
After CO2 resurfacing, approximately 20% of patients develop a localised or disseminated form of HSV.
F 7-10%, even with appropriate prophylaxis
Infections of HSV occurring as a complication of laser resurfacing tend to develop within the first postoperative week.
For HSV prophylaxis in the setting of ablative laser, patients should begin prophylaxis 1 week prior to surgery and continue for 1 week postoperatively.
F Begin by day of surgery, continue 7-10 days postop.
Ectropion of the lower eyelid is more likely to occur post ablative laser in patients who have had previous blepharoplasty or other surgery of the periorbital area.
The snap test should be performed on the lower eyelid prior to ablative laser – laser resurfacing should be avoided if the skin does not return briskly to its normal resting position.
There is no indication for altering fluence of laser passes when treating the periorbital area.
F Use lower fluence and fewer passes to reduce risk of lid eversion.
Postoperative hypopigmentation is often not seen for several months after ablative laser.
There is a lower risk of infection associated with the use of ‘closed’ dressing techniques post ablative laser.
F Higher risk reported.
Pale skin tones have a lower incidence of undesirable postoperative hyperpigmentation after ablative laser.
There are no risks associated with ablative skin resurfacing in scleroderma, LE or vitiligo.
F These conditions can worsen.
Koebnerisation of psoriasis, verrucae and molluscum can occur after ablative skin resurfacing.
Concomitant isotretinoin use could potentially lead to increased risk of postoperative hypertrophic scar formation.
T Due to effects on wound healing and collagenesis.
Treatment with laser skin resurfacing should be delayed for at least 1-2 years after cessation of isotretinoin.
F 6-12 months
There is a greater risk of scar formation after laser resurfacing, independent of the laser’s selectivity and the operator’s expertise.
Complete control of acne should be obtained prior to ablative laser skin resurfacing.
patients with mild to moderate facial photodamage with realistic treatment expectations are the best candidates for non-ablative procedures.
There is no need to avoid sun exposure prior to non-ablative laser procedures.
F Should be avoided, esp with PDL or IPL (shorter wavelength systems).
Non-ablative laser systems stimulate collagen production and dermal remodelling without wounding the epidermis.
Non-ablative lasers include mid-infrared lasers, visible light lasers and IPL systems.
Devices which emit light within the infrared portion of the electromagnetic spectrum (1000-1500nm) are weakly absorbed by superficial water-containing tissue, thereby they don’t penetrate deep tissue.
F Deeper tissue penetration is affected.
Contact cooling hand pieces or dynamic cryogen devices are used for all ablative laser systems.
F Non-ablative laser systems.
Treatment of facial photodamage with non-ablative technology does not produce results comparable to those of ablative carbon lasers.
The long pulsed Nd:YAG 1320nm wavelength laser is associated with a high scattering coefficient that allows for dispersion of laser irradiation throughout the dermis.
The long pulsed Nd:YAG 1320nm wavelength hand piece contains two portals: the laser beam itself, and a dynamic cryogen spray apparatus used for epidermal cooling.
F 3rd portal – thermal feedback sensor.
Using the Nd:YAG laser, epidermal temperatures must be kept lower than 50deg C in order to prevent unwanted sequelae from excessive heat production.
Only one treatment session with the Nd:YAG laser is usually needed for maximum mitigation of fine rhytides.
F Usually three or more typically once a month.
Side effects of Nd:YAG long pulsed laser are generally mild and include transient oedema and erythema.
The long-pulsed Diode laser has a wavelength of 1540nm.
The diode laser targets dermal water and penetrates skin to an approximate depth of 100nm.
For non-ablative lasers, the perioribtal area is usually more responsive to laser treatments than the perioral area.
The Erbium:glass laser has a wavelength of 1450nm.
The erbium:glass laser has the least amount of melanin absorbed compared with the long-pulsed Nd:YAG and diode laser systems.
Pulsed-dye lasers used for ablation have a wavelength of 585nm and 595nm.
The most common side effects of PDL treatment include mild oedema, purpura, and permanent post-inflammatory hyperpigmentation.
F Transient post-inflammatory hyperpigmentation.
IPL emits a broad continuous spectrum of light in the range of 515-1200nm.
For IPL, cut-off filters are used to eliminate shorter wavelengths depending on the clinical application, with shorter filters favouring heating of melanin and haemoglobin.
IPL can improve wrinkling, skin coarseness, irregular pigmentation, pore size and telangiectasia.
Ablative fractional lasers produce microscopic treatment zones (MTZs).
In MTZs , the epidermis is left intact, allowing for rapid repopulation of the ablated columns of tissue.
Re-epithelisiation after fractional laser treatment is completed within 2 days following treatment.
F 1 day.
Healing post fractional laser takes place through extrusion of microepidermal necrotic debris (MEND), which represents damaged epidermal components.
MEND is clinically manifest as superficial exfoliation.
During the reparative phase after non-ablative fractional laser, the skin appears erythematous.
Treatment of complete cosmetic units, or the whole face, is generally recommended with non-ablative fractional laser.
MTZs are completely replaced by new collagen over the course of 6 months.
F 3 months.
The two treatment parameters in non-ablative fractional laser are the treatment energy and the treatment density (ie. the total number of MTZs per square cm.
For scarring purposes, higher treatment energies are used with lower treatment densities for non-ablative fractional lasers.
For textural improvement with non-ablative fractional lasers, a medium energy is utilised.
With non-ablative fractional lasers, pigmentary disturbances are best treated with lower treatment energies which allow for deeper penetration.
F More superficial penetration.
Darker skin phototypes should not be treated with non-ablative fractional lasers.
F Treat safely by reducing total treatment density while maintaining energy setting.
Melasma can paradoxically darken following fractional photothermolysis.
For topical anaesthesia, preparations containing tetracaine should be avoided in patients with a known allergy to sulfa-containing medications.
The expected side effects of fractional non-ablative laser (erythema, oedema, xerosis) usually resolve within 2 weeks.
F 4 days.
Reactivation of herpes labialis tends not to occur with non-ablative laser skin remodelling.
F Can occur due to intense heat produced by laser.
Non-ablative dermal remodelling treatments are typically delivered at monthly intervals, with final clinical results taking several months after laser irradiation to be realised.
The topical photosensitiser aminolevulinic acid (ALA) is a 20% concentration solution.
The topical photosensitiser methyl aminolevulinate cream (MAL) is commercially available as a 100mg/g cream.
F 160mg/g cream.
Both ALA and MAL are strongly absorbed into sun-damaged cells and NMSCs, but not the pilosebaceous unit.
F Are absorbed into pilosebaceous unit.
ALA and MAL are transformed via the heme pathway into their active form, protoporphyrin IX (PpIX).
ALA should be used with a blue light source of 630nm peak output for PDT.
F 417nm peak output.
MAL cream under occlusion for 3 hours followed by illumination with a red light source for PDT.
T 630nm peak output.
After PDT, post-treatment crusting and erythema typically resolve within 2 days.
F Persist up to 10 days.
PDT can improve fine lines, skin texture, erythema and pigmentation.
Patients must adhere to strict sun and bright light avoidance for 48 hours after PDT.
There are no contraindications for PDT – it is a safe treatment method for NMSCs, AKs and photodamage.
F CIs incl porphyrin disorder, photosensitivity disorder or photosensitising meds.
Topical anaesthesia is required prior to application of the light source in PDT.
Forced air cooling devices can be used to alleviate any discomfort associated with PDT.
During the illumination, short breaks with cold water mists should not be used to help patients better tolerate the procedure.
F Can be used.
MAL cream should be removed prior to light activation during PDT.
Eye protection does not need to be worn during PDT.
For photodamage, PDT can be repeated monthly until desired cosmetic results are achieved.
Any remaining lesion after PDT for AKs/photodamage should be treated with further cycles.
F These should be biopsied.
After light activation during PDT, the skin should not be cleansed.
F Should cleanse thoroughly w mild soap/water.
Further activation of PpIX can occur for up to 48 hours after PDT.