Use of laser in dermatology
The laser produces a light beam which is very small sized and
because of its physical character it maintains the size and direction. So this
phenomenon of sharply focused beam of coherent light makes it suitable for a
wide range of applications. Among various application fields, in almost any of
the scientific arena you may observe laser technology applications and devices.
In recent days laser are being used in computer devices such as laser mouse,
laser presentation, CD ROMs and DVD ROMs, astronomy and communication
applications, medicine, surgery and health, cutting matters in metallurgy
industry and related industries, robotics: especially in image processing and
calculating distances, toys etc. In medical science, they have been used in
surgical operations.
There are quite a few types of lasers
used in skin laser surgery. Previous laser technologies such as the continuous
wave (CW) lasers of CO2 and argon have been largely restored with quasi-CW mode
lasers and pulsed laser systems.
The wavelength peaks of the laser
light, pulse duration and how the target skin tissue absorbs this, determine
the clinical applications of the laser types.
Laser type
|
Laser source
|
Wavelength peaks
|
CW:
emit a constant beam of light with long exposure durations
|
10,600
nm
|
|
488/514
nm
|
||
Quasi-CW:
shutter the CW beam into short segments, producing interrupted emissions of
constant laser energy
|
532
nm
|
|
Copper bromide/vapour
|
510/578
nm
|
|
Argon-pumped tunable
dye (APTD)
|
577/585
nm
|
|
Krypton
|
568
nm
|
|
Pulsed*:
emit high-energy laser light in ultrashort pulse durations with relatively
long intervening time periods between each pulse
|
Pulsed dye laser (PDL)
|
585-595
nm
|
694
nm
|
||
755
nm
|
||
1064
nm
|
||
2940
nm
|
||
10,600
nm
|
* Pulsed laser systems can be either
long-pulsed such as PDL with pulse durations ranging from 450ms to 40millisec, or
very short-pulsed (5-100ns) such as the quality-switched (QS) lasers.
Skin conditions can be treated with
lasers
Vascular lesions
Due to its superior efficiency and low
risk profile the pulsed dye laser is considered as the laser of choice of most
vascular lesions. The pulsed dye laser has a large spot size (5 to 10mm) which
allows large lesions to take care of rapidly. Side effects include
postoperative bruising (purpura) that may last 1-2 weeks and transient
pigmentary changes. Textural changes, scarring and bruising are rarely seen.
There have been successful
use of lasers to take care of a variety of vascular lesions which includes
superficial vascular haemangiomas, pyogenic granulomas, malformations(port-wine stains), facial
telangiectases, poikiloderma of Civatte and Kaposi sarcoma . Lasers that have
been used to take care of these conditions include argon, copper bromide, copper vapor, KTP, APTD,
krypton, pulsed dye lasers and Nd:YAG. Argon (CW) causes a high degree of
non-specific thermal injury and scarring and is now largely replaced by
yellow-light quasi-CW and pulsed laser therapies.
The features of new V-beam provide
ultra long pulse duration so larger energy is spotted for a longer period of
time at the target blood vessels, resulting in more uniform blood vessel
damage. This reduces the purpura seen with the earlier pulse dye lasers. The
addition of dynamic cooling increases comfort during treatment enabling higher
fluencies (energy) to be delivered safely and effectively, so fewer treatments
are required.
Vascular malformations related with
smaller more superficial blood vessels react better to treatment than deeper
larger vessels (more often arising in older individuals). Early treatment is
therefore possibly more effective. After 8 to 10 treatments on average fading
by 80% occurs. If the lesion recurs further treatment may be necessary.
The quasi-CW lasers treatment also
produce efficient results but they are may be related with most of the
incidences of scarring and textural changes. Among the side effects the most
common include mild erythema, oedema, and transient crusting.
Non-laser intense pulsed light devices
can also be used for treating vascular lesions.
Pigmented lesions and tattoos
To effectively lighten or eradicate a
range of pigmented lesions melanin-specific, high energy, QS laser systems can
be used. Treatable pigmented lesions include freckles and birthmarks including
some congenital melanocytic naevi, blue naevi, naevi of Ota/Ito and Becker
naevi. By confining their energy to the melanosomes, which are the tiny
granules containing melanin inside the pigment cells the short pulse laser
system effectively treat lesions. The results of laser treatment depend on the
depth of the melanin and the color of the lesion and it is to some degree
unpredictable. Superficially located pigment is best treated with shorter
wavelength lasers whilst removal of deeper pigment requires longems r
wavelength lasers that penetrate to greater tissue depths. Caution is needed
when treating darker-skinned people as permanent hypopigmentation and
depigmentation may occur.
Successfully treated lesions may recur.
The treatment of pigmented lesions with
atypical features needs to be biopsied to exclude malignancy. The treatment of
congenital melanocytic naevi is a controversial issue. The long-term effect of
using lasers on promoting melanoma is not known but the treatment is thought to
be low risk.
To selective destruction of tattoo
pigment with no injury to the nearby skin the QS laser systems is effective.
From the skin by searching white blood cells, tissue macrophages the altered
pigment is then removed. Depending on the color, depth and chemical character
of the tattoo ink the choice of laser can be made. Among the colors yellow,
orange and green colors are the most complicated to remove.
• Black:
QS ruby, alexandrite or Nd:YAG
• Blue
and green: QS ruby, alexandrite
• Yellow,
orange, red: QS Nd:YAG or PDL
Pigmentary and textural changes
including scars may occur as with other laser treatments.
Hair removal
To remove unnecessary and cosmetically
immobilize hair due to hypertrichosis or hirsutism lasers can be used. Dark
hair is quickly removed by using laser treatments and before regrowth is
evident it may take three to six months. Several treatment cycles are required
with the spacing between treatments dependent on the body area being treated.
Laser treatments are less painful and much quicker than electrolysis.
Complications are rare but superficial burns, pigmentary changes and even
scarring may occur. Increased growth of fine dark hair in not being treated
areas close to the treated ones has been reported. Both increased and reduced
localised sweating have been reported after treatment.
Long-pulsed ruby and alexandrite
lasers, diode (810nm), millisecond Nd:YAG and non-laser intense pulsed light
are the suitable device.
Facial wrinkles, scars, and
sun-damaged skin
High-energy, pulsed and scanned lasers
are used in facial laser resurfacing.
In decreasing and eliminating
sun-burned skin, facial wrinkles, acne scars pulsed CO2 and erbium:YAG lasers
have been successful. Against all other facial transformation systems are compared
high-energy, pulsed, and scanned CO2 laser is usually viewed as the gold
standard. Normally a fifty percent improvement is seen in patients taking CO2
laser treatment. Post-operative tenderness, redness, swelling and scarring are
the side effects of the treatment. The redness and tenderness last several
weeks, while new skin grows over the area where the damaged skin has been
removed by the laser treatments (ablative laser systems). Secondary skin
infection including reactivation of herpes is also a potential problem until healing
occurs. Extreme caution is needed when treating darker skinned individuals as
permanent loss or variable pigmentation may occur longterm.
Side effects produced by the CO2 is
similar to Erbium:YAG. These laser systems if used properly it can produce
excellent results in spite of their side effect profile and long recovery time.
Recently non-ablative lasers have been used for dermal modeling; 'non-ablative'
refers to heating up the dermalcollagen while avoiding damage to the surface
skin cells (epidermis) by cooling it. Multiple treatments are required to
smooth the skin.
Keloids and hypertrophic scars
Keloids and hypertrophic scare are not
easy to remove and usual treatments are not always effective. As an alternative
to traditional surgery vaporizing lasers (CO2 and erbium:YAG) have been more
successful. More recently PDL has been used to improve hypertrophic scars and
keloids. This may require multiple treatment sessions or the simultaneous use
of intralesional injections to gain good results. The PDL has been reported to
reduce the redness as well as improving texture and pliability of the scar.
Other uses
For the treatment of the viral warts
or destruction of the dermal blood vessels (PDL) vaporization (CO2 laser) lasers
are used) but the evidence would suggest that this is no more effective than
standard wart paints or even waiting for spontaneous clearance.
To exclude a variety of skin lesions
including seborrhoeic keratoses and skin cancers by vaporization or in cutting
mode the CO2 laser can be used. Nevertheless, conventional surgery or
electrosurgery can also be used and is generally less expensive.
For the treatment of acne, because it
has a toxic effect on the acne bacteria, Proprionibacterium acnes violet-lue
metal halide light (407-420 nm) has been used.
To produce ultraviolet radiation (308
nm) which will treat psoriasisplaques, the excimer laser uses noble gas and
halogen. However the small spot size and the tendency to cause blistering make
treatment time-consuming and difficult to perform.
Laser safety
Depending on laser system used and in
the setting the safety precautions include:
• Thorough
training of personnel
• Ensuring
the eye protection for the patient and clinic staff
• Putting
warning notice outside the procedure room
• Usage
of non-reflective instruments
• By
avoiding flammable materials
Adverse effects of laser
Laser treatments are mostly burns. The
following effects may occur:
• Bruising,
blistering and/or crusting, redness and temporary pain
• Reactivation
of herpes simplex including infection
• Pigment
changes (brown and white marks), which may be permanent
• Scarring
The laser
is used for literally hundreds of other medical purposes. But there are still
many medical conditions which cannot be treated with laser lights. As a matter
of fact, while the laser is a marvel of science and can be an effective medical
tool, it cannot cure everything. Yet only a small fraction of laser potential
application has been explored and still scientists are working on it and
implications of laser in dermatology in getting effective day by day. In the
end, this miracle of science has only been existed since 1960, the future looks
promising.
No comments:
Post a Comment