Energy-based treatment of the ageing face for skin resurfacing – Ablative and non-ablative lasers & Photodynamic therapy Flashcards
Regarding photodamage, ablative laser skin resurfacing offers the most substantial clinical improvement.
T
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.
T
Extrinsic ageing effects are usually limited to the epidermis and upper papillary dermis and are therefore amenable to treatment with laser.
T
Ablative lasers are selectively absorbed by water and act to vaporise skin in a controlled manner.
T
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.
F
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.
T
Ablative resurfacing lasers include: pulsed CO2 (10600nm), pulsed erbium:YAG (2940), and fractionated (10600 and 2940nm)
T
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.
T
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.
T
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.
F
Areas with thinner skin require fewer passes with a CO2 laser.
T
CO2 laser resurfacing of non-facial areas (eg neck, chest) should be avoided due to the relative paucity of pilosebaceous units in these areas.
T
CO2 laser resurfacing can offer at least a 50% improvement over baseline in overall skin tone and wrinkle severity.
T
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.
T
Absolute CI to CO2 laser resurfacing includes active infection or an inflammatory skin condition involving the areas to be treated.
T
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.
T
YAG laser emits a 2940nm wavelength light corresponds to the 3000nm absorption peak of water-
T
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.
T
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.
T
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.
T
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.
T
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.
T
Areas treated with Er:YAG immediately whiten after treatment and then the white colour quickly fades.
T
Short-pulsed Er:YAG can be used for superficial or dermal lesions
T
Short-pulsed Er:YAG tends to have a longer recovery period.
F Shorter.
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.
T
Post-op erythema from Er:YAG resolves within 1-2 weeks.
F 3-4 weeks.
Er:YAG is contraindicated in darker skin phototypes.
F
The major disadvantage of short-pulsed Er:YAG is its limited ability to effect significant collagen shrinkage.
T
The final result with Er:YAG ablation is typically less impressive compared with CO2 resurfacing for deeper rhytides.
T
For mild photodamage, Er:YAG only typically produces improvement of about 20%.
F 50%.
Ablative fractional resurfacing devices have the ability to achieve comparable clinical results to non-fractional methods.
T
Ablative fractional resurfacing devices can keep the majority of the dermis intact, thus allowing quicker recovery periods and an improved safety profile.
F Epidermis.
Fractional lasers deliver energy through macroscopic zones of thermal injury, leading to coagulation necrosis and resultant new collagen formation.
F Microscopic.
Annular coagulation of dermal collagen occurs with fractional ablative laser, with increasing fluences resulting in increasing treatment depths.
T
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.
T
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.
T
With fractional laser, ablation depth and the residual thermal damage depend on energy density and the number of stacked pulses used.
T
Fractional and non-fractional laser treatments should never be combined.
F
Fractional laser ablation requires longer recovery time than other ablative lasers.
F Average 5-7 days.