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Handbook of Laparoscopy Instruments, 2023, 29-38 29
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Optical Devices
CHAPTER 4
Venkatesh Rewale1, Aditya Patel1 and Lamture Yeshwant Ramrao
1
Department of General Surgery, JNMC, Sawangi (Meghe), Wardha, India
Abstract: Optical devices in laparoscopic surgery comprised a telescope (0-30-45
degree telescopes), a light source, a light cable, a camera, and a monitor. All play an
essential role from the beginning to the end of the procedure. The outcome of a suitable
laparoscopic procedure depends on optical devices. The telescope used may have 0-3-
-45 degree view. The light source can be Helium or xenon. Xenon is costly but
resembles natural light more, giving a good in vivo view.
Optical fibers carry light into the abdomen, and the rod lens mechanism moves images
to the camera and then to monitor, to result in a successful procedure.
This chapter will go through the mechanism and working of light cables, cameras and
light sources used in laparoscopy.
1,*
Keywords: Camera, Halogen bulb, Light source, Monitor, Telescope.
INTRODUCTION
Minimally invasive surgery has undergone significant advances and has changed
the way operations are performed. Technological advances have produced
progressively smaller laparoscopic instruments and higher-quality imaging that
allow laparoscopic surgeons to perform precise dissection with minimal bleeding
through most dissection planes, even those that are highly vascular.
Illumination of the peritoneal cavity is essential in laparoscopic and hysteroscopic
surgery. There are a variety of light sources with varying spectral emissions and
illumination power. Light originates from an object when both bulbs are
illuminating that should be inspected to confirm for heated sufficiently, and the
color (wavelength) of the light emitted varies with the temperature of the source.
This property of color temperature is measured in degrees Kelvin (KO). Light
sources with higher KO contain more high frequency (blue) wavelengths,
resulting in a brighter and more accurate image. As light loses heat (lower KO),
*
Corresponding author Lamture Yeshwant Ramrao: Department of General Surgery JNMC, Sawangi (Meghe),
Wardha; India; E-mail: yash18671@gmail.com
All rights reserved-© 2023 Bentham Science Publishers
Lamture Yeshwant Ramrao (Ed.)
30 Handbook of Laparoscopy Instruments Rewale et al.
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its spectral emission shifts from blue to red, causing the image to assume a
reddish tint. Until the mids-1960s, endoscopic lighting was less expensive, it emit
relatively little blue colour light, consisted of the traditional incandescent
lightbulb. Output was generally between 75 and 250 W, although light sources of
less than 150W were generally avoided in gynecological endoscopy. An
incandescent light bulb transforms approximately 97% of electrical energy into
heat, while 2% to 3% is converted into visible light. This is particularly crucial in
operative endoscopy where the loss of the light source during dissecting or
haemostatic procedures would pose a significant risk to the patient.
Hence, it is essential that we have the understanding about the light cables,
cameras and light sources used in laparoscopy.
Imaging System
The imaging system consists of a laparoscope, i.e. telescope, a camera, a light
source, a light cable, and a monitor.
Laparoscopes
In 1952, British physicist Hopkins invented the telescope. Laparoscopes may be
developed optics (Figs. 1 and 2a and b). Surgical stainless steel is the main
component of these Laparoscopes. An optical lens encompassing spacers and
glass lenses that are perfectly aligned. Commonly used are rigid ones having
angles of 0°, 30°, and 45°. The diameter of the telescope varies. It may be 10 mm,
5 mm, or 3 mm. 10 mm scope is routinely used in adult practice, while a 3 mm
scope is used in pediatric practice. The scope provides an attachment to a light
cable. Fogging of the lens occurs intraoperatively due to increased temperature in
the abdomen, which is prevented or cleared by dipping the tip in warm water. It
should always be adequately cleaned after use, mainly the light cable slot,
telescope eyepiece and patient end. It is sterilized with chemical sterilizers.
Light Source
Luminescence of white light is obtained by a high-intensity halogen lamp,
mercury or xenon. Bundles of Fiberoptics deliver this irradiation [1].
Laparoscopic light sources comparable and similar to natural light are considered
good sources of light. Three types of light sources are routinely used: halide,
halogen, and xenon. The most common type of light source used is the halogen
bulb. The halogen lamp comes with a condenser system.
Optical Devices Handbook of Laparoscopy Instruments 31
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EYESHIELD
LIGHT POST
Typical Hopkins Rod Lens System used in Laparoscopic Usurgery
EYEPIECE LENS
OUTER TUBE
FIELD STOP AND DATUM
OCULAR WINDOW
Eyeshield
Proximal end
Backend of
Laparoscope
Light Post
(light guide connection)
Fig. (1). Diagrammatic representation of the telescope.
ILLUMINATION FIBRE
OPTIC CARRIER TUBE
Optical Axis
of Laparoscope
ROD RELAYS
ANGLE OF VIEW PRISM
OBJECTIVE LENS
NEGATIVE LENS
DISTAL WINDOW
0 degree
30 degree
45 degree
Fig. (2a). 0-degree and 45-degree telescopes.
32 Handbook of Laparoscopy Instruments Rewale et al.
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Fig. (2b). Tips of 0-degree and 45-degree telescopes with magnified view.
Alternative to glass, Quartz is utilized to permit higher currents and temperatures,
leading to greater light output.
Hot filament evaporates the tungsten. This tungsten combines with halogen and
forms a new compound which is attracted back to the filament with a higher shelf
life. Thus Filaments life is increased by combining the halogen with the tungsten.
This sharp and clear white light is cheaper and a good option.
Xenon (Xe) lamp is without filament and has cathode and anode exchange of
electrons, it gives better visual clarity and is near to natural light colour spectrum,
but is expensive. Xenon is of 175-300 watts. Regulation of light intensity is made
either manually or automatically.
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Heat filters, condensing lenses, bulbs and intensity-controlling knobs
(manual/automatic) are the various constituents of the light source unit.
Before the initiation of any procedure, appropriate balancing of white light is very
much necessary to obtain natural colour (Fig. 3).
Fig. (3). Light source.
Light Cable
The light cables are of two types, one is fluid-filled and other is fiber optic [2].
The cables are of variable sizes. The liquid crystal gel cables are made more rigid
by a metal covering, which makes them less flexible and difficult to maintain and
store. Fiber optic cable is user-friendly than a fluid-filled cable (Fig. 4 see both a
and b). Fiber optic cables do not relay a spectrum of light accurately, but they are
flexible, whereas fluid filled cables accurately relay the complete spectrum of
light but are very rigid. It offers little light loss but is less durable than liquidfilled light guide cables because some optical fibers break with continuous usage.
Care of Light cable after the procedure –
●
Not to do acute angle twisting while keeping in a box.
●
Once the procedure is done, the cable should be detached from the telescope
first that helps in cooling down the cable.
●
End of the cable should be wiped with alcohol.
●
Technicians should keep the light emitting tip of the light source properly – it
may cause burn to the drapes and skin of the patient and even retinal damage if
it goes directly into the eyes of the surgeon or scrub staff.
34 Handbook of Laparoscopy Instruments Rewale et al.
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Fig. (4a). Light cable.
Optical fiber
Core
(purest SiO
SiO2 silicon oxide
possible)
2
Fig. (4b). Light cable diagrammatic representation.
Cable
Buffer coating
Optical sheath
: Different refraction index,
(SiO
2
less pure than core)
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Thermas for prevention of fogging of camera lens (see Fig. 5).
Fig. (5). Thermos flask.
Cameras
It is an essential part of the imaging system. The simultaneous vision of the
operation theatre's operative field to all the members is possible because of these
cameras. Various complicated synchronizing movements are required to perform
complex operations, which are easily permitted by these cameras. The charged
coupled device (C.C.D.) sensor contains pixels (small pieces of silicon) arranged
in columns and rows. Nowadays, high resolution with good optical sharpness and
lightweight cameras are available. It may be a single chip or three chips. A singlechip camera has a resolution of point 450-600, while three-chip cameras have
more than 750 horizontal lines, which gives better visual clarity. Usually, singlechip cameras are used for routine laparoscopic surgeries. It has a white balancing
and zoom option (Figs. 6a and b). C.C.D. (charge-coupled device) or computer
chip (solid-state silicon) forms the basis of all laparoscopic cameras. Light
receptors on-chip or pixel number defines the clarity or resolution of the image.
250,000 to 380,000 pixels are present in the Standard cameras commonly used in
laparoscopy.
36 Handbook of Laparoscopy Instruments Rewale et al.
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Fig. (6a). Camera with the cable.
ocular coupler
zoom optics 25-50 mm
program / function
selector
focusing ring
video sensor housing
Fig. (6b). Camera with a cable.
Television Monitor With Instrument Trolley
High-resolution video monitors are required for the suitable reproduction of an
endoscopic image. Three-chip cameras require monitors with 700 lines resolution
to realize the improved resolution of extra-chip sensors. VHS recorders, video
printers and sometimes DVD recorders are standard documentation types of
equipment housed in the video cart see (Figs. 7a and b).
Optical Devices Handbook of Laparoscopy Instruments 37
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Fig. (7b). Instrument trolley.
38 Handbook of Laparoscopy Instruments Rewale et al.
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CONCLUSION
In the recent era, systems producing three-dimensional images are currently under
development and seem to facilitate surgical performance [3]. Medical industries
are adopting flat-panel monitors whose resolution determines a better image. Thus
newer video recording systems document and record the performed procedures
better.
REFERENCES
[1] Quint R. Physics of light and image transmission.Laparoscopy. Baltimore: Williams and Wilkins
1977; pp. 18-23.
[2] Hopkins HH. Physics of the fiberoptic endoscope.Endoscopy. New York: Appleton-Century-Crofts
1976; pp. 27-63.
[3] Cicione A, Autorino R, Breda A, et al. Three-dimensional vs standard laparoscopy: comparative
assessment using a validated program for laparoscopic urologic skills. Urology 2013; 82(6): 1444-50.
[http://dx.doi.org/10.1016/j.urology.2013.07.047] [PMID: 24094658]
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