Tesfaye beyene project

WOLAITA SODO UNIVERSITY
COLLEGE OF NATURAL AND COMPUTITIONAL SCIENCE
DEPARTMENT OF PHYSICS
A PROJECT ON PRINCIPLES OF CO2 LASER
BY
TESFAYE BEYENE DAGNE
ID NO PHYS/SUM/1508/08
ADVISOR: TSEGAYE B. (MSc.)
20, January, 2021
Wolaita Sodo, Ethiopia

I
APPROVAL SHEETT SENIOR PROJECT
DEPARTEMENTOF PHYSICS
WOLAITA SODO UNIVERSITY
Submitted by:
Name Signature Date
__________________ ________________
Name of Adviser Signature Date
__________________ ________________
Name of External Examiner Signature Date
_________________ __________________ ________________
Name of Internal Examiner Signature Date
___________________ _________________ _______________

II
Acknowledgment
First and almost I would like to thank to praise Almighty God, who gave me the insight strength and
courage to begin and complete this study. Next to this, my heartfelt gratitude goes to my adviser
Tsegaye Bojago for his constructive advice and precious co-operation, willingness and comment that
he has given me while I was conducting this project work. My deepest gratitude also goes to my
family who credited for their moral and financial support throughout my study in the university and
for the completion of my project work. Finally, I would like to express my grateful thank and best
gratitude to my friends who have supported me in sharing ideas, editing and printing.

III
Abstract
Since its invention in 1960, the laser has found diverse application in engineering and industry
because of it stability to produce high power beams. In the field of metal processing, laser
applications include welding, drilling, cutting, scribing, machining, heat treatment, cladding and
alloying. In other fields, such as medical surgery, lasers are also used extensively. Lasers are used in
a wide range of applications such as, laser surgery, heat treatment, welding and drilling. The much
higher reflectivity of CO2 laser from liquid, vapor and plasma of a tin target results in the production
of optically thinner plumes with higher velocity and in a better formation of plasma properties towards
more efficient extreme ultraviolet lithography source. In this project work, briefly discusses. The
application of CO2 laser in medical, the principle of CO2, real life application of CO2. Result and
discussion, methods, conclusion and summery
Keywords: Laser,(Light Amplification by stimulated Emission of Radiatio )
CO2(Carbon dioxide) and Applications

IV
TEBLE OF CONTENT
Contents Page
APPROVAL SHEETT SENIOR PROJECT..............................................................................................I
Acknowledgment.......................................................................................................................................II
Abstract ...................................................................................................................................................III
TEBLE OF CONTENT............................................................................................................................IV
UNIT ONE................................................................................................................................................1
1. Definition of CO2 Laser......................................................................................................................1
1.1. CO2 laser andit’s Application............................................................................................................................................2
1.1.1. Clinical application in neurosurgery.................................................................................................................................. 2
1.2. The real life situation of CO2 laser ...................................................................................................................................4
1.3. Objective...................................................................................................................................................................................4
1.3.1. General objective ............................................................................................................................................................... 4
1.3.2. Specific objective of the study........................................................................................................................................... 4
1.4. Significance of project...........................................................................................................................................................4
UNIT TWO...............................................................................................................................................5
2. History of CO2 laser..........................................................................................................................5
2.1. Laser Nobel Prizes .................................................................................................................................................................5
2.2. Principles of Laser Micro laryngoscopy ........................................................................................................................5
A. Wavelength....................................................................................................................................6
B. Tissue Interaction...........................................................................................................................6
C. Delivery Systems ............................................................................................................................6
2.3. CO2 Laser Safety Guidelines.........................................................................................................7
 General Guidelines.............................................................................................................................7
2.4. Surgical Principles .........................................................................................................................7
UNIT THREE...........................................................................................................................................8
3. METHODS........................................................................................................................................8
CHAPTER FOUR.....................................................................................................................................9
2. Result and Discussion.............................................................................. Error! Bookmarknot defined.
6. REFERENCE...................................................................................................................................... 11

V
List of Figures
Fig. 1……..
Fig 2………

1
UNIT ONE
INTRODUCTION
1.1`Backgroundof CO2 Laser
The CO2 laser produces a beam of infrared light with the principal wavelength bands centering at
10,600 nanometers. Collisional energy transfer between the nitrogen and the carbon dioxide molecule
causes vibrational excitation of the carbon dioxide, with sufficient efficiency to lead to the desired
population inversion necessary for laser operation. It is easy to actively Q-switch a CO2laser by means
of a rotating mirror or an electro-optic switch, giving rise to Q-switched peak powers up to giga watts
(GW) of peak power[2[.
The carbon dioxide laser (CO2 laser) was one of the earliest gas lasers to be developed (invented by
Kumar Patel of Bell Labs in 1964 .and has been extensively used in the next two decades as an
incision tool in increasingly wide areas, such as neurosurgery, dermatology and plastic surgery,
otorhinolaryngology, ophthalmology, gynecology, and general surgery. In 1984, its reliability resulted
in its approval by the U.S. Food and Drug Administration, and thus, medical use of lasers became
more prevalent. Currently, the CO2laser is considered an indispensable piece of diagnostic and
therapeutic equipment. It is still one of the most useful. Carbon dioxide lasers are the highest-power
continuous wave lasers that are currently available. They are also quite efficient: the ratio of output
power to pump power can beas large as 20%.The CO2laser produces a beam of infrared light with the
principal wavelength bands centering around 9.4 and 10.6 micrometers [1].
CO2lasers are attracting attention as cutting tools. They are able to seal lymphatic and blood vessels
less than 0.5-mm wide and can reduce intraoperative bleeding and the occurrence of postoperative
swelling. CO2lasers emit a longer wavelength than those transmitted by other types of lasers. Their
penetration depth of 0.03 mm is very safe[3]. Coagulation in small blood vessels, as well as sealing of
lymphatic and small peripheral nerves, has been reported in experimental studies using CO2lasers; this
sealing alleviates postoperative pain.
The CO2 laser also offers more comfort to patients by reducing intraoperative bleeding and
postoperative edema, facilitating the process of wound healing after surgery. The boundaries between
the tissues receiving heat damage and the surrounding intact tissue are very well defined. A CO2 laser
can evaporate through the surrounding tissue without physical force, sealing the vessel and minimizing
bleeding; thus, it is useful when a bloodless view is required during surgery. Moreover, wounds can be
treated in a sterile manner because of high-temperature evaporation of tissue lesions.
Regarding its disadvantages, the equipment is expensive, operators require time to become familiar
with it, and the sophisticated operation is technically difficult. Therefore, more repetitions are required
to gain the necessary experience and practice. In addition, there is a risk of fire if the laser is used
improperly. It can also damage the cornea; thus, eye protection is needed for the surgeon and the

2
patient. Because the gas discharged from the vaporization of tissue contains an excess of CO2or virus
particles, it can be harmful to the human body [4].
The CO2 laser is most widely used in the field of neurosurgery, and it is mainly used in the removal of
tumors by evaporation where surgical approach of the tumor site is difficult[5]. It is common opinion
that the CO2laser is most effective with skull base, ventricular, brainstem, and spinal cord tumors
(Powers, Cush et al. 1991; Origitano and Reichman 1993). In particular, it is most effective in
removing a meningioma that is relatively hard or has less vascular distribution to be calcified. In
addition, it is suitable for removing a low-grade glioma that is relatively rigid (Deruty, Pelissou-
Guyotat et al. 1993).
1.1 CO2 laser and its Application
Co2 has wide Applications in engineering and industry also in the field of metal processing include
welding, drilling, cutting, scribing, machining, heat treatment, cladding and alloying. In other fields,
such as medical surgery, lasers are also used extensively. In this paper we are going to focus on the
application of CO2 medical surgery, like Brain tumor surgery, spin surgery, disk herniation and discal
cyst.
1.1.1. Clinical application in neurosurgery
The CO2 laser is most widely used in the field of neurosurgery for removal and evaporation of tumors
located in difficult surgical fields, such as the base of the skull, ventricles, brainstem, and spinal cord.
1.1.1.1. Application of CO2 laser on Brain tumor surgery
The CO2 laser is the main instrument used in brain surgery. It has the advantage of rapidly removing
separated tumor cells and exact irradiation of target cells by a microsurgical technique where the CO2
laser is installed with a microscope. However, as energy cannot pass through an optical fiber, it is
inconvenient to use the equipment. It has limited function in bleeding control, as control of bleeding is
not possible in a vessel with a diameter 0.5 mm, necessitating the use of the equipment in conjunction
with other equipments for severe bleeding management.
The CO2 laser has been used in brain microsurgery after Steller. [6] had first successfully used it in
removing a recurrent glioma in 1969. The most ideal treatment of a brain tumor is minimizing damage
to the normal brain tissue and removing only the tumor area. To overcome the surgical difficulty of
avoiding damage to the brain tissue, a special instrument was developed. Theoretically, lasers have
several advantages. First, although the surgical field is narrow, it makes surgery possible. Other small-
sized surgical approaches are facilitated to minimize injury to normal brain tissue. Second, brain
retraction is minimized, thus causing less damage to normal brain tissue. Third, laser beam minimizes
injury to surrounding tissues and enables removal of a tumor with less thermal injury. Fourth, lasers
have a coagulating property that lessens bleeding of the surgical field. Fifth, operation time is
shortened [7].

3
1.1.1.2. Application 0f CO2 laser on Spine surgery
Since the first trial of Nd:YAG in a lumbar disk surgery in 1986 (Choy, Case et al. 1987), there have
been many reports about the usefulness of different kinds of lasers in disk surgery (Nerubay, Caspi et
al. 1997; Hellinger 1999; Houck 2006). Nerubay et al. reported that 50 patients with low back and
radicular pains were successfully treated by percutaneous laser nucleolysis using a CO2 laser
(Nerubay, Caspi et al. 1997), and successful vaporization of the disk was accomplished in animal
models (Stein, Sedlacek et al. 1990).
Considering the similarity between the disk and the meniscus [8], we cite studies on the effect of the
CO2 laser on the meniscus. According to these research results, there was a considerable proliferation
of cells resembling chondrocytes after 2 weeks of the CO2 laser treatment and there was definitely an
increase in the production of ground substance and immature collagen fibers after 4 weeks; the
collagen had become well reorganized into a logical orientation, resembling the normal architecture of
fibrocartilage, after 10 weeks [8].
These animal and clinical studies strongly support the claim that CO2 lasers can safely and feasibly be
used for the removal of protruded disks and discal cysts. [9]Moreover, the CO2 laser, when attached to
an operating microscope, allows for quick and easy removal of the discal cyst and, if needed, easy
vaporization of disk material.
1.1.1.3. Application 0f CO2 laser on Disk herniation
Laser removes disk material by vaporization [10] and consequently lowers intradiskal pressure
(Gropper, Robertson et al. 1984). In spine surgery, the use of a laser has advantages over scalpel use in
terms of precision; the ability to be used on delicate tissues; minimal tissue manipulation; and less
bleeding, swelling, and trauma (Jeon, Lee et al. 2007). It is especially useful in the small spaces
involved in herniated disks (Kim, Choi et al. 2009). Therefore, a laser is an effective tool for
performing a minimally invasive spinal surgery with percutaneous and open spinal procedures.
The CO2 laser-assisted micro discectomy could be an effective alternative to conventional micro
discectomy techniques[11]. Because the CO2 laser enabled effective removal of extraforaminal
lumbar disk herniation(EFLDH) via a narrow extraforaminal operative corridor without excessive loss
of the facet joint and/or the par interarticularis, a thorough decompression of the extraforaminal and/or
the foraminal zone was achieved while preserving spinal stability.
1.1.1.4. Application 0f CO2 laser on Discal cyst
Many kinds of surgical methods have been introduced for the treatment of discal cysts. Most discal
cysts reported have been treated by open surgical excision or with some direct intervention, such as
computed tomography-guided aspiration and steroid injection. [11] reported that the CO2 laser, when
attached to an operating microscope, allows for quick and easy removal of a discal cyst and, if needed,
easy vaporization of disk material. In his study, 14 cases of discal cyst that caused the same symptoms

4
and signs as those of lumbar disk herniations were excised successfully by open surgery using a CO2
laser.
After the intraoperative removal of the discal cyst, the authors found the communication hole between
the cyst and the protruded disk. They then used the heat energy produced by CO2 lasering and
removed the pulled-out disk fragment, if any existed, after pushing into the disk space with a right-
angled probe [12].
1.2 The real life situation of CO2laser
The CO2 laser has found diverse application in engineering and industry because of it stability to
produce high power beams. In the field of metal processing, laser applications include welding,
drilling, cutting, scribing, machining, heat treatment, cladding and alloying. In other fields, such as
medical surgery, lasers are also used extensively. Lasers are used in a wide range of applications such
as, laser surgery, heat treatment, welding and drilling.
1.3 Objective
1.1.2. Generalobjective
The general objective of this project is to explain the principle of CO2 laser.
1.1.3. Specific objective of the study
The specific objective of this project is_:
1. To describe Clinical application of CO2 laser in neurosurgery.
2. To describe Application 0f CO2 laser on Discal cyst.
3. To describe Application 0f CO2 laseron Spine surgery.
1.4 Significance of project
The main significance of this project is used to reference as project as well as other somebody who
wants to get knowledge from The application of light, types of light, characteristics of light and also it
will prepare to the next education level.

5
UNIT TWO
2. History of CO2 laser
The term laser was first used by Gordon Gould in 1959. He also sketched the first laser resonator.Th
e first working laser was built By Theodore Maimanat Hughes Research lab, in 1960. Laser was a s
olid state ruby laser, optically pumped. This unique powerful and coherent light source received
enormous attention for various applications. In 1916, Albert Einstein predicted the existence of stim
ulated emission, based on statistical physics considerations. Never considered the possibility of amp
lification.Amplification of light through stimulated emission requires population inversion.
In equilibrium, lower energy levels are always more populated. As a result, absorption always domi
nates.In order for the stimulated emission to become significant, higher energy levels should be artif
icially made more populated. This is called population inversion. It is achieved via «pumping”.
There are many ways of pumping, including electrical and optical.
2.1. LaserNobel Prizes
 1964: Charles H. Townes, Alexander M. Prokhorov, and Nicolay G. Basov for the constructio
n of oscillators and amplifiers based on the maser‐laser principle.
 1966: Alfred Kastler for the discovery and development of optical methods for studying resona
nces in atoms.
 1971: Dennis Gabor for his invention and development of the holographic method.
 1981: Arthur Schawlow and Nicolaas Bloembergen for the development of laser spectroscopy
 Laser Nobel Prizes
 1997: Steven Chu, Claude Cohen‐
Tannoudjiand William D. Phillips for the development of methods to cool and trap atoms with
laser light
 1999: Ahmed Zewailfor his studies of the transition states of chemical reactions using femtose
cond spectroscopy.
 2000: ZhoresI. Alferovand Herbert Kroemerfor developing semiconductor heterostructuresuse
d in high‐speed‐and optoelectronics
2.2. Principles of Laser Micro laryngoscopy
The modern challenge of using medical lasers is the surgeon’s ability to deliver the right amount of
energy at the right wavelength to the right tissue while minimizing damage to collateral tissue [13].
This process by which laser energy is restricted to a particular site is a result of the selective
absorption of the chromospheres at that site and was first described by Anderson et al. as “selective
photothermolysis.” The following section will consider the major concerns confronting surgeons when
using lasers in a clinical setting.

6
A. Wavelength
Unlike the energy emitted from ambient light sources, laser light is monochromatic and usually of a
single wavelength, with all photons collimating into a single, thin beam of homogeneous energy. The
challenge of laser surgery is finding a wavelength in which energy is absorbed by target tissue and
scattered or transmitted by surrounding structures. When laser light is delivered to the chromophores
within the target, energy is absorbed within that tissue. Some common chromophores targeted by
surgical lasers are hemoglobin, melanin, water-containing soft tissue, and covalent bonds found in
major structural proteins.[14] Depending on the chosen wavelength, either coagulation, vaporization,
or a combination both will take place. Tissues heated to 80–100°C will suffer plasma denaturation,
resulting in vessel closure and hemostasis. Temperatures above 100°C will cause vaporization through
rapid volumetric expansion of intracellular water stores, a technique that is useful for separating or
ablating tissues. A laser’s wavelength also correlates with the depth at which the energy is delivered.
Therefore, greater depths of tissue disruption are achieved at longer wavelengths until reaching the
wavelength specific for the absorption of water, near 2,000 nm[15].
B. Tissue Interaction
While appropriate wavelength determination is critical for specific tissue targeting, the time in which
the energy is delivered is also of consequence. Under prolonged exposure times, photo thermal effects
cause collateral coagulation necrosis, as heat transfers uniformly to surrounding tissues. However, if
the pulse width is too short, the absorbing tissue may heat rapidly [16]. Extreme temperature
differences between target tissue and collateral structures have been shown to cause vaporization and
shock wave damage commonly referred to as a photomechanical effect. Consequently, nonspecific
thermal damage occurs when the pulse width exceeds the thermal relaxation time for the tissue. Thus,
the larger the specific target, the larger the thermal relaxation coefficient. Generally, subcellular
organelles achieve photolysis within a nanosecond domain, cellular disruption occurs on a
microsecond scale, and hemostasis is achieved within millisecond exposure times. In actual practice,
all of these interactions occur concomitantly, but by selecting the proper wavelength, intensity, and
pulse duration, the surgeon can maximize the desired effects [17].
C. Delivery Systems
While recent advancements in the field have provided more options for delivery systems, laser type is
still the major determinant. Traditionally, the CO2 laser has been of the most use for laryngologists.
Traditionally, an articulating arm is required for the delivery of CO2 laser energy to the treatment site.
This delivery system requires a hollow tube with several joints or articulations that allow some
maneuverability. At each articulation, a set of mirrors are positioned to reflect the beam around the
corner. Great care must be taken when using such a system, as jarring or vibrations may cause
misalignment within the internal mirror system. Laryngologists have also benefited from the addition
of several attachments used at the end of articulating arms [18]. Micromanipulators are used to couple

7
laser operation and microscopy. A greater amount of precision and beam control can be managed by
hand-manipulated devices. The micromanipulators can control laser spot size. This is an essential
variable from an ultimate tissue interaction perspective. Spot size, power, energy setting, and duration
have a major role in the effect of the laser on the tissue. The smaller the spot size, the greater the
energy delivered per unit area. Thus, when working with the typical very small spot sizes found with
the CO2 laser micromanipulators, the power settings should be kept quite low[19].
2.3 CO2 Laser SafetyGuidelines
 General Guidelines
1. Remember, lens focuses beam and renders it collimated.
2. Moving hand piece away [defocusing] leads tologarithmic fall in irradiance; use this to
coagulate.
3. Super-pulse CO2 laser reduces dwell time, maximizes power.
4. Use continuous wave in highly vascular lesions and areas, debunking and where esthetics is
not an issue e.g., foot.
5. Under-treat, eschew therapeutic greed.
6. Laser settings in texts are often for collimated hand pieces, read carefully before applying.
One-third to one-fourth the irradiance suggested in the texts seems to deliver the results.
In the vast majority of laryngeal laser surgery, relatively low power settings are employed to
minimize collateral heat damage. For the purposes of this chapter, all laser settings described are
used in the context of a micromanipulator with a 250-μm spot size [20]. Laser settings are
generally set below 10 W, using an intermittent or super pulse mode. Continuous firing mode is
rarely employed and can sharply increase the chances of immediate (laser fire) or late
complications (glottic web/stenosis), due to the substantial power delivery in this mode.
Intermittent delivery or pulsed delivery (e. g., super pulse) allows some thermal relaxation time in
between laser delivery, thus minimizing collateral heat damage[21].
2.4 SurgicalPrinciples
 SmokeEvacuation
Laser vaporization results in significant smoke accumulation at the operative site, and must be
rapidly removed to maintain visualization. [22]Suction tubing should be connected to a side
channel of the laryngoscope to maintain continuous smoke evacuation. It should be noted,
however, that supplemental smoke evacuation may be necessary.

8
UNIT THREE
3. Methodology
3.1Data Collectionmethods
Under this parts of the project there are many pointes discussed in brief ways about the principle of
CO2 laser. Surgical Principles, the application of CO2 laser and the theories of laser, for this reason, to
get detail information about CO2 laser, reviews of literature from different books and internet are the
main means of gathering inform.

9
UNIT FOUR
4.1 Summary and Conclusion
Conclusion
 The CO2 laser is most widely used in the field of neurosurgery for removal and evaporation
of tumors located in difficult surgical fields, such as the base of the skull, ventricles,
brainstem, and spinal cord.
 CO2 lasers are attracting attention as cutting tools
 laser beam minimizes injury to surrounding tissues and enables removal of a tumor with less
thermal injury.
 For most purpose, available light should be used whenever possible, and artificial light should
be made to look as” natural” as possible unless the photographer has some very specific
artistic or aesthetic purpose in mind.
 Laser vaporization results in significant smoke accumulation at the operative site, and must be
rapidly removed to maintain visualization.

10
Summary
Co2 has wide Applications in engineering and industry also in the field of metal processing include
welding, drilling, cutting, scribing, machining, heat treatment, cladding and alloying. In other fields,
such as medical surgery, lasers are also used extensively. In this paper we are going to focus on the
application of CO2 medical surgery, like Brain tumor surgery, spin surgery, disk herniation and discal
cyst.

11
6. REFERENCE
[1] Trimas SJ, Ellis DA, Metz RD. The carbon dioxide laser: An alternative for the treatment of
actinically damaged skin. Dermatol Surg 2012 ;23:885-9.
[2] Phahonthep R, Sindhuphak W, Sriprajittichai P. Lidocaine iontophoresis versus EMLA cream for
CO2 laser treatment in seborrheic keratosis. J Med Assoc Thai 2004;87:S15-8.
[3] Fulton JE, Rahimi AD, Helton P, Dahlberg K, Kelly AG. Disappointing results following
resurfacing of facial skin with CO2 lasers for prophylaxis of keratosis and cancers. Dermatol Surg
2020 ;25:729-32.
[4] Fitzpatrick RE, Goldman MP, Ruiz-Esparza J. Clinical advantage of the CO2 laser superpulsed
mode. Treatment of verruca vulgaris, seborrheic keratosis, lentigines and actinic cheilitis. J
Dermatol Surg Oncol 2012 ;20:449-56.
[5] Quaedvlieg PJ, Ostertag JU, Krekels GA, Neumann HA. Delayed wound healing after three
different treatments for widespread actinic keratosis on the atrophic bald scalp. Dermatol Surg
2003;29:1052-6.
[6] Lauchli S, Kempf W, Dragieva G, Burg G, Hafner J. CO2 laser treatment of warts in
immunosuppressed patients. Dermatology 2003;206:148-52.
[7] Geronemus RG, Kauvar AN, McDaniel DH. Treatment of recalcitrant verrucae with both the
ultrapulse CO2 and PLDL pulsed dye lasers.Plast Reconstr Surg 2018 ;101:2010.
[8] Landsman MJ, Mancuso JE, Abramow SP. Carbon dioxide laser treatment of pedal verrucae. Clin
Podiatr Med Surg 2020 ;9:659-69.
[9] Lim JT, Goh CL. Carbon dioxide laser treatment of periungual and subungual viral warts.
Australas J Dermatol 2018;33:87-91.
[10] Hohenleutner U, Wlotzke U, Konz B, Landthaler M. Carbon dioxide laser therapy of a
widespread epidermal nevus. Lasers Surg Med 1995;16:288-91.

12
[11] Khoo L. Carbon dioxide laser treatment of benign skin lesions. National Skin Centre Experience
2001;12:2.
[12] Verma KK, Ovung EM. Epidermal and sebaceous nevi treatment with CO2 laser. Indian J
Dermatol Venereol Leprol 2002;68:23-4.
[13] Ratz JL, Bailin PL, Wheeland RG. Carbon dioxide laser treatment of epidermal nevi. J Dermatol
Surg Oncol 2016;12:567-70.
[14] Boyce S, Alster TS. CO2 laser treatment of epidermal nevi: Long-term success. Dermatol Surg
2002;28:611-4.
[15] Hohenleutner U, Landthaler M. Laser therapy of verrucous epidermal naevi. Clin Exp Dermatol
2016;18:124-7.
[16] Raulin C, Schoenermark MP, Werner S, Greve B. Xanthelasma palpebrarum: Treatment with the
ultrapulsed CO2 laser. Lasers Surg Med 2000;24:122-7.
[17] Alster TS, West TB. Ultrapulse CO2 laser ablation of xanthelasma. J Am Acad Dermatol
1996;34:848-9.
[18] Ullmann Y, Harshai Y, Peled IJ. The use of CO2 laser for the treatment of xanthelasma
palpebrarum. Ann Plast Surg 2011 ;31:504-7.
[19] Gladstone GJ, Beckman H, Elson LM. CO2 laser excision of xanthelasma lesion. Arch
Ophthalmol 2010;103:440-2.
[20] Krupa Shankar DS, Kushalappa AA, Suma KS, Pai SA. Multiple dermatofibromas on face
treated with carbon dioxide laser. Indian J Dermatol Venereol Leprol 2007;73:194-5.
[21] Simo R, Sharma VL. The use of the CO2 laser in rhinophyma surgery: Personal technique and
experience, complications and long-term results. Fac Plast Surg 2016;14:287-95.
[22] Goon PK, Dalal M, Peart FC. The gold standard for decortication of rhinophyma: Combined
erbium-YAG/CO2 laser. Aesthetic Plast Surg 2004;28:456-60.

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