Specifications

• A simple binocular coaxial illumination surgery microscope with a compact design and high flexibility to meet the requirements of general animal microsurgery
• Eyepiece magnification: 12.5X
• Objective lens focal length: 200mm
• Working distance: 190mm
• Total magnification: 5.3X, 8X, 12X
• Field of view diameter: 38mm, 25mm, 17mm
• Diopter adjustment range: ±5D
• Interpupillary distance adjustment range: 50mm-70mm
• Lighting source: 12V/100W, cold reflection medical halogen bulb
• Illumination type: 6°+0° cold light source coaxial illumination
• Coaxial illumination object surface illuminance: ≧20000lx
• Cross arm extension radius: 870mm
• Fine focusing stroke: 30mm
• Voltage: AC220V±10%, 50Hz±1Hz
• Power: 120VA
• Fuse: AC250V T1.25A
• Whole machine weight: 41kg

Introduction

An operating or surgical binocular microscope is an optical device that presents the surgeon with stereoscopic vision, and a high-quality magnified and illuminated image of the minute structures in the surgical region. The surgical microscope is usually used to perform microsurgery. Primarily a radical idea, the operating microscope has turned into a necessary tool since the first known usage of the binocular microscope during surgery. Its powerful stereoscopic magnification and illumination of the operative bed prompted its quick acceptance by numerous surgeons all over the world. The introduction of the surgical microscope in the operating room opened a new chapter in the history of microsurgery. It extended the limits of the field, enhanced patient outcomes, and made the development of subspecialties possible. It granted access to regions of the brain and spinal cord that were previously thought to be impossible to reach. The increased magnification allowed for smaller incisions, enhanced visibility, and dissection of sensitive tissues. It provided sufficient hemostasis when working through constricted and deep surgical sites and also frequently helped to cut down the time period of the surgery and decrease anesthetic dangers. On the whole, the binocular surgical microscope has been extensively used in the fields of neurosurgery, plastic surgery, dentistry (particularly endodontics), ENT surgical procedures, and ophthalmic surgeries. Ever since the surgical microscope has been introduced into the operating room, various factors like the size, focus, and flexibility of the microscope have proved to be challenging, and solutions have frequently led to new issues. According to an estimate, the majority of surgeons may spend around 40% of their total time during surgery making adjustments to the surgical microscope. Focusing is normally manual, even though some more advanced microscopes have an autofocus aspect included. The advanced technology of surgical instrument tracking autofocus will have the capacity to extensively reduce the surgical duration and furthermore enhance the efficiency of the surgeon. In general, a surgical microscope may cost a few thousand dollars for a basic model, whereas highly developed models might be significantly more costly. Additionally, specialized microsurgical tools might be needed to take full advantage of the enhanced vision the microscope provides. It may take time to ace the operational aspect of the surgical microscope. However, the surgical microscope is unmistakably superior to the customary surgical loupes that require high magnification and adjustable focus. Even so, the complex mobility and the elevated cost of the surgical microscope have given rise to the necessity for more transportable solutions. A head-mounted operating microscope was lately launched in the market. It brings together the portability of the surgical loupes and the magnification and focusing capacity of a microscope. A fundamental feature of any surgical microscope is its design.  The device is designed in such a manner that the surgeon concentrates fully on the surgical procedure while remaining comfortable and free of eye strain. The design of the microscope likewise frees the surgeon’s hands to operate. Most of the microsurgical operations take place in a small space or through narrow gaps and in these cases, it is imperative to the surgeon that he retains a sufficiently well-lit binocular vision in the recesses of the area. In such circumstances, the stereoscopic perspective provided by the binocular surgical microscope is the most valuable feature of the device. The binocular surgical microscope serves two major functions: magnification of the operative field and illumination. With the assistance of a foot or hand switch, it can enlarge structures up to 40+ times. Along with increased magnification, an inbuilt halogen or Xenon lamp gives outstanding lighting right above the surgical area. Advanced microscopes can self-adjust the strength of the illumination to avoid tissue damage, as the microscope shifts nearer or further away from the operative field. Additionally, the surgical microscope has three oculars. One of the oculars is positioned on the side; it tends to fit on either side of the central oculars. The adjustments may affect the stability of the microscope, and the device requires balance prior to its usage. Auto-balance features are as easy as the push of a button and have the capacity to re-balance the microscope securely during the process. The binocular surgical microscope is comprised of numerous joints to allow for 180° movement, including adjustments for the various seating positions of the patient. The commercial surgical microscopes are mainly positioned on a wheelbase.  They can be placed inside the operating room or shifted from one room then onto the next. The modern surgical microscopes are equipped with cameras that can capture high-resolution images or record high-quality videos. These pictures and video recordings can be stored in integrated or external hard drives or memory sticks, or even transferred onto DVD and Blu-ray discs.

Principles

The magnification of an image is a dependent value and depends on the size of an image as projected on top of the retina of the eye. Consequently, the magnification of a picture is increased by merely reducing the distance between the eye and the object. When the object in question draws nearer to the observing eye, the size of the projected image on the retina is increased.  If the retinal region covered by the projected image is doubled, then the magnification would be observed as 2x or two times larger than what it was before, taking the preceding position as a base value. With the utilization of the binocular microscope, and without altering the distance value, the size of the reflected image of an item can be increased on the retina. The amount of increase, at that point, turns into the magnification value of the specific binocular microscope, for example, a 7x binocular has a predetermined estimate of increasing by seven-fold. The light that the surgical microscope illuminator transmits to enlighten the surgical site can be varied. One method to change the light is to vary the voltage to the light bulb. The majority of the microscope floor stand power supplies have a prerequisite to change the strength of the light by this technique. Below the microscope, a particular amount of light will be transmitted, and any adjustment made in the magnification of the microscope will have no impact on the amount of light being transmitted from the microscope. However, variations made in the magnification of the microscope do enhance or reduce the amount of light which will be transmitted back through the microscope and on top of the retina of the eye of the observer. Furthermore, the surgical microscope is capable of providing stereoscopic vision in confined spaces by decreasing the required interpupillary distance needed for binocular vision. The distance between the frontal lenses of the binocular tube of the microscope is just 16 mm, while the standard interpupillary distance is around 60 mm. This implies that light reflected from deep basal structures towards the surgical microscope during an operation utilizing fissure, sulci or transcortical methods, will lead to a stereoscopic image when only a 16mm image penetrates the eye through a microscope. Conversely, if the surgeon is assisted with magnification loupes in place of the surgical microscope, the eyes will not be able to retain stereoscopic vision in such a constricted area

History

Origin

The first use of a microscope in the operating room was initiated by the Swedish Carl Nylen in 1922 when Nylen chose to utilize a monocular Brinell-Leitz microscope, rather than a loupe, for performing surgery on a patient with chronic otitis media with labyrinthine fistulas. However, monocular microscopes did not offer depth perception, and the lack of a light source in the initial designs led to the dimness of the image as the magnification increased. In 1922, Gunnar Holmgren utilized a binocular microscope to overcome the absence of depth perception and additionally, connected a light source to the microscope to resolve the latter setback. This led to a new era in the advancement of numerous microsurgical specialties, for example, neurosurgery, ENT, ophthalmology, and plastic surgery (Uluç, Kujoth, & Başkaya, 2009).

Development

In 1948, Richard A. Perritt began to use an adaptation of the Bausch & Lomb slit-lamp microscope which was hanging from a weighted table stand along with its coaxial lighting unit and variable magnification. In 1952, Hans Littmann, a physicist at Zeiss, began a new era by developing a microscope that was capable of altering magnification without altering the focal length. Horst L. Wullstein, an otolaryngology surgeon, constructed a microscope built on a stand provided with a rotating arm. In 1953, Littmann profited from Wullstein’s design and knowledge and produced the “Zeiss OPMI 1” (Zeiss Operating Microscope 1), which was increasingly stable, easy to operate, and had better coaxial lighting than any other commercially available operating microscope. During that same year, Heinrich Harms and Günter Mackensen modified this microscope for use in ophthalmological treatment during middle ear surgery. The operating microscope was further integrated into the field of neurosurgery by Theodore Kurze in 1957. From 1958 to 1970, the operating microscope underwent several modifications and was equipped with customized stands, motorized zoom objective, short ocular tubes, and a slit lamp, film, TV camera, and other sources of illumination. Zeiss designed the OPMI CS in 1991 and the OPMI ES in 1994, particularly made for neurosurgery. In 1997, Zeiss introduced the OPMI Neuro and later provided this microscope with a Multivision system that projects superior imaging techniques (for instance, MR imaging, CT, etc) directly into the eyepieces (Uluç, Kujoth, & Başkaya, 2009).[

Apparatus and Equipment

The modern binocular surgical microscope has a compact design and high flexibility and may be mounted on a stand, or set on a tabletop. The basic surgical microscope framework typically consists of a binocular head with adjustable eyepieces, an illumination module, a fiber optic cable, a locking clamp, and foot controls. The microscope itself consists of the objective lens, diopter lock button, diopter ring, magnification changer, and maneuvering handle. The binocular head along with the eyepieces is basic, but it is also possible to attach a separate head for an associate which is called a teaching head. The binocular head may rotate separately and have its own magnification levels. The foot controls are used for tilting, focusing, and zooming during the surgical procedure. The illuminator provides incandescent, fiber optic and halogen illumination.  The objective lens of the surgical microscope has a variable focal length which is dependent on the depth of the operative field enabling the microscope to be adjusted at different distances. The magnification is usually set in three to six presets varying from 6X – 25X. The magnification changer is a lens system positioned between the objective lens and the binocular system and enables constant adjustment of magnification. Specifications

• Eyepieces 12.5X focus length of objective: 200mm
• Working distance 190mm
• Total magnification 5.3X, 8X, 12X

Most the microsurgical operations take place in a small space or through narrow gaps and in these cases it is imperative to the surgeon that he retains a sufficiently well-lit binocular vision in the recesses of the area. In such circumstances, the stereoscopic perspective provided by the binocular surgical microscope is the most valuable feature of the device.

• Diopter adjustment range +5D
• Pupil distance range 50mm~70mm
• Bulb 12V/100W (Medical halogen lamp Bulb with cold reflection)
• Type of Illumination 6°+ 0°cold light source coaxial illumination
• The intensity of Illumination 20000Lx or up
• The maximum stretching radius of the arm is 870mm
• Vertical movement range (from floor to front surface of the objective) 700mm~1100mm
• Range of fine focusing adjustment 30mm
• Input voltage AC220V±10%, 50Hz±1Hz
• Input power 120VA
• Power AC250V T1.25A
• Net weight 41kg

Training Protocol

The basic aim of the surgical microscope is to improve the visual perspective of the surgeon through magnification, illumination, and resolution.

• First, complete the installation of the device and shift the surgical microscope to an appropriate location for the surgery and bolt the castors.
• Adjust the counter-balanced arm and the main microscope to a convenient position and screw the corresponding lock shut.
• Next, hold the main surgical microscope with the hand and release the up-down positioning knob and rotate the balance knob until the main microscope has free up and down movement.
• Then, switch on the power button, turn the brightness switch on and loosen the corresponding lock to move the device.
• Pull the main microscope over the surgical field within the height of the working distance (which relies upon the focal length of the objective lens), until the images can be viewed in the binoculars and tighten the corresponding lock.
• Adjust the position of the binoculars by hand to achieve the appropriate papillary distance.
• Next, rotate the magnification changer knob to achieve the required magnification level.
• Adjust the illuminator module to achieve the required illumination on the surgical site and get the best clear visual image by the motorized up-down focus method or activate the focus function on the foot control.
• After adjusting the focus, check if the two eyes have varying diopters and alter the diopter on the eyepiece for each eye.
• Use the back-forth inclination function by rotating the inclination knobby back and forth and positioning the main microscope at a proper place.
• In the same manner, adjust the right and left inclination adjustment and bring the microscope to an appropriate position.
• After the procedure is over and the surgical microscope is not in use, switch the bright switch off, and after a few minutes turn off the power switch of the unit.
• Release the corresponding lock and move the arm and main microscope to a suitable spot and wrap it with a plastic-proof cover.

Applications In Surgical Experiments

• The objective lenses, eyepieces, and accessories that are not being utilized must always be kept in dust-free containers.
• The external surfaces of optical parts like eyepieces and objective lenses only need to be cleaned when necessary without utilizing any chemical cleaning agent.
• The dust on the surface of optical components may be blown off by utilizing a squeeze blower, or it can be eliminated by utilizing a clean grease-free brush.
• Use an anti-fogging agent to protect the eyepiece optics from fogging.
• All mechanical surfaces of the instrument can be simply cleaned with a damp cloth without the use of aggressive agents.
• Wrap the foot pedal with a clear plastic cover to avoid damage to the electronics from surgical and cleaning fluids.
• Abstain from looking directly into the light source, e.g., into the objective lens or a light guide.
• Do not run the instrument in locations at risk of explosives or containing inflammable anesthetics or volatile chemicals.
• Do not place or utilize the equipment in damp rooms and avoid exposing the instrument to water.
• Promptly unplug any instrument that emits smoke, sparks, or odd sounds.

Strengths

The binocular surgical microscope is a high-grade technological instrument that requires regular maintenance.

• The objective lenses, eyepieces, and accessories that are not being utilized must always be kept in dust-free containers.
• The external surfaces of optical parts like eyepieces and objective lenses only need to be cleaned when necessary without utilizing any chemical cleaning agent.
• The dust on the surface of optical components may be blown off by utilizing a squeeze blower, or it can be eliminated by utilizing a clean grease-free brush.
• Use an anti-fogging agent to protect the eyepiece optics from fogging.
• All mechanical surfaces of the instrument can be simply cleaned with a damp cloth without the use of aggressive agents.
• Wrap the foot pedal with a clear plastic cover to avoid damage to the electronics from surgical and cleaning fluids.
• Abstain from looking directly into the light source, e.g., into the objective lens or a light guide.
• Do not run the instrument in locations at risk of explosives or containing inflammable anesthetics or volatile chemicals.
• Do not place or utilize the equipment in damp rooms and avoid exposing the instrument to water.
• Promptly unplug any instrument that emits smoke, sparks, or odd sounds.

Limitations

• The binocular surgical microscope improves the surgeon’s view by providing great magnification, powerful illumination, and a stereoscopic perspective during surgery.
• The basic surgical microscope typically consists of a binocular head, adjustable eyepieces, illumination, foot controls, objective lens, diopter lock button, diopter ring, and magnification changer.
• The device is used in various surgical disciplines such as microvascular surgery, plastic and reconstructive surgery, neurosurgery, otorhinolaryngology, transplantation procedures, oncology, urology, dentistry, etc.
• The binocular surgical microscope eliminates the problems that arise from standing for long durations during conventional surgeries such as fatigue, neck pain, eye strain, and posture-related problems.
• The device can be rather bulky and take up a lot of space as well as require proper and constant maintenance.

References

Cordero, I. (2014). Understanding and caring for an operating microscope. Community Eye Health, 27(85), 17. Girman, P., Kriz, J., & Balaz, P. (2015). Rat Experimental Transplantation Surgery. Switzerland: Springer International. Green, C. J. (1987). Microsurgery in the clinic and laboratory. Laboratory Animals, 21(1), 1-10. doi: 10.1258/002367787780740734 Jabbour, P. M. (2013). Neurovascular Surgical Techniques. New Delhi: Japyee Brothers Medical Publishers. Kamath, D., Paul, J., Joseph, A., & Varghese, J. (2015). Magnification in Endodontics. J Odontol Res, 3(1), 31-34. doi: 10.18231/2456-8953.2018.0001 Siemionow, M. Z. (2015). Plastic and Reconstructive Surgery. London: Springer. Uluç, K., Kujoth, G. C. & Başkaya. M. K. (2009). Operating microscopes: past, present, and future. Neurosurg Focus, 27(3), E4. doi:10.3171/2009.6.FOCUS09120. Yasargil, M. G. (1969). Microsurgery: Applied to Neurosurgery. New York: Academic Press.