Lens Endoscope Research Articles

An Innovate Robotic Endoscope Guidance System for Transnasal Sinus and Skull Base Surgery: Proof of Concept.

Objective Advanced transnasal sinus and skull base surgery remains a challenging discipline for head and neck surgeons. Restricted access and space for instrumentation can impede advanced interventions. Thus, we present the combination of an innovative robotic endoscope guidance system and a specific endoscope with adjustable viewing angle to facilitate transnasal surgery in a human cadaver model. Materials and Methods The applicability of the robotic endoscope guidance system with custom foot pedal controller was tested for advanced transnasal surgery on a fresh frozen human cadaver head. Visualization was enabled using a commercially available endoscope with adjustable viewing angle (15-90 degrees). Results Visualization and instrumentation of all paranasal sinuses, including the anterior and middle skull base, were feasible with the presented setup. Controlling the robotic endoscope guidance system was effectively precise, and the adjustable endoscope lens extended the view in the surgical field without the common change of fixed viewing angle endoscopes. Conclusion The combination of a robotic endoscope guidance system and an advanced endoscope with adjustable viewing angle enables bimanual surgery in transnasal interventions of the paranasal sinuses and the anterior skull base in a human cadaver model. The adjustable lens allows for the abandonment of fixed-angle endoscopes, saving time and resources, without reducing the quality of imaging.

Review of Techniques to Achieve Optical Surface Cleanliness and Their Potential Application to Surgical Endoscopes

A clear visualization of the operative field is of critical importance in endoscopic surgery. During surgery the endoscope lens can get fouled by body fluids (eg, blood), ground substance, rinsing fluid, bone dust, or smoke plumes, resulting in visual impairment. As a result, surgeons spend part of the procedure on intermittent cleaning of the endoscope lens. Current cleaning methods that rely on manual wiping or a lens irrigation system are still far from ideal, leading to longer procedure times, dirtying of the surgical site, and reduced visual acuity, potentially reducing patient safety. With the goal of finding a solution to these issues, a literature review was conducted to identify and categorize existing techniques capable of achieving optically clean surfaces, and to show which techniques can potentially be implemented in surgical practice. The review found that the most promising method for achieving surface cleanliness consists of a hybrid solution, namely, that of a hydrophilic or hydrophobic coating on the endoscope lens and the use of the existing lens irrigation system.

Innovations in surgical scopes—wireless steerable endoscopes and magnetic cameras

Conventional rod lens endoscope has for decades facilitated minimally invasive surgery (MIS) procedures. Video-assisted thoracic surgery (VATS) has continued to evolve in pursuit of minimizing surgical access trauma leading to the development of uniportal VATS. However, operating through a single small incision using the rod lens endoscope proves to be challenging. The view and maneuverability of the endoscope is limited by the unidirectional approach, and in addition a crowded port site increases risk of interference and fencing between instruments. These challenges have inspired innovation in endoscopic systems to allow wider range of viewing directions and angles with minimum scope movement. In particular, flexible endoscopes and magnetic endoscopes have unique advantages and potential over conventional rigid equipment. Flexible endoscopes with articulating tips offer distal dexterity, and provide wide range of viewing angles despite limited motion of endoscope shaft. Whereas magnetic anchored and actuated endoscopes go beyond tip dexterity, abandoning the rod body completely, and exploit magnetic linkage to navigate along intrathoracic surface, overcoming limit of unidirectional approach. Through wireless actuation, magnetic endoscopes also provide many views without occupying the access port, reducing incision size and risk of instrument interference. To apply the devices clinically, current prototypes still require lens cleaning strategy and sensors to match image quality of commercial systems. With these issues addressed, these novel systems may allow safer and more efficient performance of uniportal VATS, benefiting both surgeons and patients.

Endoscopic ear surgery- acomplement to microscopic ear surgery.

Wullstein, the founder of modern microscopic ear surgery, already used an oto-endoscope intraoperatively. However, it is only after the recent development of modern video-endoscopy with high-definition, 4K, and 3‑dimensional imaging that endoscopically guided surgery of the middle ear is gaining some importance. Key ventilation routes like the isthmus tympani and the epitympanic diaphragm can be visualized far better using an endoscope than with a microscope. Going through the external meatus, surgery of middle ear pathologies is possible without external incision. This type of primary endoscopic ear surgery has to be distinguished from secondary endoscopic ear surgery, where standard microscopic ear surgery is supplemented by endoscopic surgery. Having to hold the endoscope in one hand, surgery has to be performed single-handedly, which is awkward. In cases of extensive bone removal or excessive bleeding, the view through the endoscope lens is obscured; therefore; the endoscope cannot fully substitute the microscope. It is, however, an interesting adjunct to microscopic ear surgery.

Transparent antifouling material for improved operative field visibility in endoscopy

Camera-guided instruments, such as endoscopes, have become an essential component of contemporary medicine. The 15-20 million endoscopies performed every year in the United States alone demonstrate the tremendous impact of this technology. However, doctors heavily rely on the visual feedback provided by the endoscope camera, which is routinely compromised when body fluids and fogging occlude the lens, requiring lengthy cleaning procedures that include irrigation, tissue rubbing, suction, and even temporary removal of the endoscope for external cleaning. Bronchoscopies are especially affected because they are performed on delicate tissue, in high-humidity environments with exposure to extremely adhesive biological fluids such as mucus and blood. Here, we present a repellent, liquid-infused coating on an endoscope lens capable of preventing vision loss after repeated submersions in blood and mucus. The material properties of the coating, including conformability, mechanical adhesion, transparency, oil type, and biocompatibility, were optimized in comprehensive in vitro and ex vivo studies. Extensive bronchoscopy procedures performed in vivo on porcine lungs showed significantly reduced fouling, resulting in either unnecessary or ∼10-15 times shorter and less intensive lens clearing procedures compared with an untreated endoscope. We believe that the material developed in this study opens up opportunities in the design of next-generation endoscopes that will improve visual field, display unprecedented antibacterial and antifouling properties, reduce the duration of the procedure, and enable visualization of currently unreachable parts of the body, thus offering enormous potential for disease diagnosis and treatment.

In-cylinder combustion visualization of Jatropha straight vegetable oil and mineral diesel using high temperature industrial endoscopy for spatial temperature and soot distribution

Endoscopic optical visualization technique is reliable for investigations in harsh environments such as IC engine combustion chambers. In this study, high temperature industrial endoscopy was employed to a production grade diesel engine for optical diagnostics of in-cylinder combustion. Engine cylinder-head was suitably modified for visual access of combustion. Combustion characteristics such as in-cylinder pressure, heat release rate (HRR), start of combustion (SoC), combustion duration (CD), etc., for Jatropha straight vegetable oil (SVO) and mineral diesel were investigated using Industrial endoscope, which can withstand such harsh environment. In-cylinder combustion images were recorded using a high-speed charge coupled device (CCD) camera. Recorded images were corrected using calibration tool to remove endoscopic lens distortions (spherical aberration). Spatial soot and flame temperature distributions were analysed from the corrected combustion images using soot analysis and correlated colour temperature (CCT) methods. Spatial soot and temperature distributions for the test fuels indicated that luminous regions in the combustion chamber were the prime locations for soot formation. These regions also indicated peak temperature zones in the field of view. This study is unique, where in-situ combustion characteristics were determined for SVO and baseline diesel using endoscopic visualization. This study generated valuable information about in-cylinder spatial combustion of SVO, which can be utilized for combustion and emission optimization of SVO fuelled engines.

Diamond turning fabrication of an ultra-compact endoscope

Abstract In this paper, we propose a technique by integrating mechanical mounts into lens elements to fulfill a self-aligned and self-assembled optical system. To prove this concept, we designed, fabricated, and tested an ultra-compact endoscope that adopts this technique. By taking advantages of the specially designed fixture and observing the interference fringes between the lens and fixture, we developed a method to minimize decenter and tilt between the two surfaces of the endoscope lens during the diamond turning fabrication process. The integrated mechanical mounts provide an easy assembly process for the endoscope system while maintaining high accuracy in system alignment. With the application of heat shrink tube as the endoscope system holder and to block stray light, the proposed endoscope system has the advantages of low cost, compact size, and high imaging quality.

Transtentorial transcollateral sulcus approach to the ventricular atrium: an endoscope-assisted anatomical study.

OBJECTIVE Conventional approaches to the atrium of the lateral ventricle may be associated with complications related to direct cortical injury or brain retraction. The authors describe a novel approach to the atrium through a retrosigmoid transtentorial transcollateral sulcus corridor. METHODS Bilateral retrosigmoid craniotomies were performed on 4 formalin-fixed, colored latex-injected human cadaver heads (a total of 8 approaches). Microsurgical dissections were performed under 3× to 24× magnification, and endoscopic visualization was provided by 0° and 30° rigid endoscope lens systems. Image guidance was provided by coupling an electromagnetic tracking system with an open source software platform. Objective measurements on cortical thickness traversed and total depth of exposure were recorded. Additionally, the basal occipitotemporal surfaces of 10 separate cerebral hemisphere specimens were examined to define the surface topography of sulci and gyri, with attention to the appearance and anatomical patterns and variations of the collateral sulcus and the surrounding gyri. RESULTS The retrosigmoid approach allowed for clear visualization of the basal occipitotemporal surface. The collateral sulcus was identified and permitted easy endoscopic access to the ventricular atrium. The conical corridor thus obtained provided an average base working area of 3.9 cm2 at an average depth of 4.5 cm. The mean cortical thickness traversed to enter the ventricle was 1.4 cm. The intraventricular anatomy of the ipsilateral ventricle was defined clearly in all 8 exposures in this manner. The anatomy of the basal occipitotemporal surface, observed in a total of 18 hemispheres, showed a consistent pattern, with the collateral sulcus abutted by the parahippocampal gyrus medially, and the fusiform and lingual gyrus laterally. The collateral sulcus was found to be caudally bifurcated in 14 of the 18 specimens. CONCLUSIONS The retrosigmoid supracerebellar transtentorial transcollateral sulcus approach is technically feasible. This approach has the potential advantage of providing a short and direct path to the atrium, hence avoiding violation of deep neurovascular structures and preserving eloquent areas. Although this approach appears unconventional, it may provide a minimally invasive option for the surgical management of selected lesions within the atrium of the lateral ventricle.

Dual Endoscopic Endonasal Transsphenoidal and Precaruncular Transorbital Approaches for Clipping of the Cavernous Carotid Artery: A Cadaveric Simulation.

Background Endoscopic skull base approaches are being used to address complicated neurovascular pathology. These approaches are safest when proximal vascular control of the cavernous carotid artery (CavCA) can be obtained. Methods We present a cadaver-based anatomic simulation study showing the feasibility of clip placement for the CavCA as it courses through the cavernous sinus. The arterial vessels were injected with red microfil (Flow Tech, Carver, Massachusetts) to enhance visibility. The endoscope was directed through a precaruncular transorbital approach and instrumentation was managed through an endonasal transsphenoidal approach. Results The dual approach minimized the "coning down" and instrument "sword fighting" that occurs as the rod lens endoscope and instruments are used laterally and posterior toward the clivus and brainstem. The precaruncular transorbital approach improved visualization of the clip application and improved the functional working area. The transorbital port allowed better appreciation of the distal clip tines, and the laterally positioned cranial nerves. Conclusions The advantages may be most realized in the setting of endoscopic endonasal resection of highly vascular lesions and/or bleeding from a ruptured aneurysm being clipped. Simulated training provides an excellent opportunity to enhance skill sets and increase familiarity with anatomical visualization before entering the operative arena.

Dual-Channel Minimally Invasive Endoscopic Port for Evacuation of Deep-Seated Spontaneous Intracerebral Hemorrhage with Obstructive Hydrocephalus

In minimally invasive endoscopic port surgery, the medium is air, and the image is clearer than in fluid. The most commonly used port is a single-channel port, which accommodates the rod lens of the endoscope and 2 microsurgical instruments. This setup decreases the freedom of movement of the 3 instruments, making the bimanual procedure difficult. We describe a novel "dual-channel" endoscopic port to facilitate a bimanual refinement procedure for removing deep-seated spontaneous intracerebral hematomas, and we demonstrate the feasibility of this method. The small channel accommodates a 0° endoscope lens, and the large channel accommodates 2microsurgical instruments. This method was used in 8patients with deep-seated spontaneous intracerebral hematomas with obstructive hydrocephalus. It was necessary to evacuate the deep-seated hematomas in these patients as soon as possible to recover the circulation of cerebrospinal fluid. Dual-channel port surgery was performed in 8 patients with an average age of 55 years (range, 44-79 years). The time from ictus to surgery ranged from 4 hours to 12 days. The duration of drainage tube placement was 2-5 days. The hematomas in all patients, in the third ventricle or thalamus, were evacuated thoroughly. In each patient, improvements in Glasgow Coma Scale scores were observed from admission to discharge. The dual-channel endoscopic port facilitated bimanual refinement microsurgery during the evacuation of deep-seated intracerebral hematomas, and it prevented the disturbance of the 3 instruments without restraining the scope of the operation during the microsurgical procedure.

Design of a foveated wide-angle endoscopic lens

Recent improvements in optics miniaturization have led to the development of multiple techniques in order to perform minimally invasive endoscopic procedures. Among them, the wide-angle lens is often used for its simplicity and ability to collect a large amount of information in one capture. We report the design and analysis of two versions of a wide-angle endoscope with a full field of view of 180 deg. The difference between the two designs resides in the direct control over distortion that was used in order to achieve foveated imaging. By doing so, the local magnification at the center of the image can be controlled during the design process, allowing for a better resolution in the center of the field of view. The design is also folded in order to address certain issue concerning the region of interest during an endoscopic procedure.

Endoscopic Cycloplasty (ECPL) and Lens Extraction in the Treatment of Severe Plateau Iris Syndrome.

To describe the anatomic and clinical results of the treatment of severe plateau iris syndrome with lens extraction and endoscopic cycloplasty (ECPL). A secondary aim was to describe 4 novel ultrasound biomicroscopy (UBM) measurements for plateau iris syndrome. Prospective case series with UBM evaluation. Included were 12 eyes of 6 patients with plateau iris refractory to laser iridotomy and iridoplasty, miotic and other glaucoma medical treatment, with appositional angle closure in at least 3 quadrants. Treatment consisted of lens extraction and ECPL, an endoscopic diode laser treatment of the ciliary processes in the superior, nasal, and inferior quadrants. UBM measurements were taken in all quadrants before and after surgery. The untreated temporal quadrants were used as controls. Measurement parameters included: anterior chamber depth (ACD), angle opening distance (AOD 500), trabecular ciliary process distance (TCPD), iris ciliary process distance (ICPD), iris depth (ID), iridocorneal angle (ICA), and sulcus angle (SA). Four novel measurements included: ciliary process thickness (CPT), ciliary process width (CPW), ciliary process area (CPA), and iris ciliary process contact length (ICPCL). Visual acuity, intraocular pressure, glaucoma medications, and complications were also followed. The ACD, AOD 500, and ICA all increased significantly (P<0.001). ICPD, CPT, CPW, CPA, and ICPL all decreased significantly (P<0.01). Parameters remaining unchanged were: TCPD, ID, and SA. The untreated quadrants showed similar measurements to the preoperative measurements. There were no serious complications noted. Treating the ciliary processes with diode laser using an endoscopic approach (ECPL) and lens extraction, results in opening of the anterior chamber angle and shrinkage of the ciliary processes in the treated areas. This effect seems to be primarily a result of the laser treatment in combination rather than the lens extraction alone. This effectively reverses the anatomic cause and angle closure of plateau iris syndrome.

Facile design of plant-oil-infused fine surface asperity for transparent blood-repelling endoscope lens

Minimally invasive medical operations, especially endoscope operations, have attracted much attention and play a major role in modern medicine.

Endoscopic total removal of lateral ventricular cysticercus cyst

A patient presented with recurrent episodes of generalized seizures for last 1 year followed by progressive holocranial headache, vomiting and visual blurring at the peak of headache for last 2 months. On admission, the patient was neurologically intact with bilateral papilledema. Magnetic resonance imaging (MRI) of brain showed cystic lesion at the left lateral ventricle with hydrocephalus (Figs 1a and 1b). Endoscopic complete cyst removal was done under general anesthesia. The procedure was performed using a zero degree rigid lens endoscope (Karl Storz 2.7 mm Neuro-Endoscope System, COMPANY). The patient was placed supine, with no rotation of the head to maintain vertical orientation. Frontal precoronal burr-hole approach through left side was used. The endoscope was set in and secured to the accompanying endoscope holder that was attached to the operative table. Normal saline solution was used for gravity-fed irrigation. Once cyst was identified with the endoscope, an assessment was made whether the cyst could be removed safely. The cyst was blocking the left foramina of Monro and loosely adherent to the ependymal wall. With the help of saline irrigation and the mechanical pressure of endoscope,

Posterosuperior extension of caudal septal incision for endoscopic septoplasty.

Endoscopic septoplasty provides several advantages over traditional headlight septoplasty in terms of better visualization. However, surgeons may experience frequent soiling of the endoscope lens by blood from the incision site and awkwardness in finding adequate space for the endoscope and dissectors in narrow septal mucosal tunnels. Here, we propose a simple and safe modification for endoscopic septoplasty. A total of 21 patients underwent endoscopic septoplasty using a new modification. Briefly, a posterosuperior extension incision was made along the dorsal septum at the superior end of the caudal septal incision, and a posteroinferior-based septal mucosal flap was developed and placed laterally over the inferior turbinate during surgery. The new modification reported here provided clear endoscopic visualization and a comfortable working space from making the incision to closing the wound. In addition, no significant complications related to this modification, such as increased operation time, intraoperative or postoperative bleeding, delayed wound healing, synechia, nasal septal perforation, and reduced olfaction, were observed. Adding a posterosuperior extension incision to the caudal septal incision might be a safe and efficient modification for endoscopic septoplasty.

Transorbital transnasal endoscopic combined approach to the anterior and middle skull base: a laboratory investigation.

Orbital approaches provide significant trajectory to the skull base and are used with differently designed pathways. The aim of this study is to investigate the feasibility of a combined transorbital and transnasal approach to the anterior and middle cranial fossa. Cadaveric dissection of five silicon-injected heads was used. A total of 10 bilateral transorbital approaches and 5 extended endonasal approaches were performed. Identification of surgical landmarks, main anatomical structures, feasibility of a combined approach and reconstruction of the superior orbital defect were examined. Rod lens endoscope (with 0° and 45° lenses) and endoscopic instruments were used to complete the dissection. The transorbital approach showed good versatility and provides the surgeon with a direct route to the anterior and middle cranial fossa. The transorbital avascular plane showed no conflict with major nerves or vessels. Large exposure area from crista galli to the third ventricle was demonstrated with significant control of different neurovascular structures. A combined transorbital transnasal approach provides considerable value in terms of extent of exposure and free hand movement of the two surgeons, and allows better visualisation and control of the ventral skull base, thus overcoming the current surgical limits of a single approach. Combination of these two minimally invasive approaches should reduce overall morbidity. Clinical trials are needed to evaluate the virtual applications of this approach.

Dual view capsule endoscopic lens design.

A dual view capsule endoscopic (DVCE) lens is proposed with front view and back view functions. This is a hybrid lens with a catadioptric mirror and an aspherical surface to support both view functions. The field of view (FOV) for the front view function is 90 degrees. The FOV for the back view function is 260 to 290 degrees. The TV distortion for the front view and back view function is under 30% and 25%. The corner relative illuminations for the two view functions are above 0.53. The Modulation Transfer Function (MTF) performance at the Nyquist Frequency for the two view functions can be kept above 0.35, even under tolerance they can remain above 0.2. Moreover, the telecentric conditions at the image plane of the DVCE system can support constant magnification through focusing. This condition can reduce the measurement error by slightly defocusing of the lens. Thus, the two view functions can offer physicians a wide viewing angle to deal with lesions over the fold.

Transorbital Transnasal Endoscopic Combined Approach to Anterior and Middle Skull Base: Laboratory Investigation

Objectives: Orbital approaches provide significant trajectory to the skull base and are used with different designed pathways. The aim of this study is to investigate the feasibility of a combined endoscopic transorbital and transnasal approach to the anterior and middle cranial fossa. Methods: Cadaveric dissection of 5 silicon-injected heads. A total of 10 bilateral transorbital approaches and 5 extended endonasal approaches were performed. Identification of the surgical landmarks, main anatomical structures, feasibility of combined approach, and reconstruction of the superior orbital defect were examined. Rod lens endoscope (with 0° and 45° lenses) and endoscopic instruments were used to complete the dissection. Results: The transorbital approach showed great versatility and provided the surgeon a direct route to the anterior and middle cranial fossa. Anterior/posterior ethmoid arteries, optic nerve, and superior orbital fissure were the landmarks for the superior orbital wall craniectomy. Transorbital avascular plane showed no conflict with major nerves or vessels. Large exposure area from crista galli to the third ventricle was demonstrated with significant control of different neurovascular structures. The combined transorbital transnasal approach provided considerable value in form of extent of the exposure and the free hand movement of the 2 surgeons. Conclusions: Combined transorbital transnasal approach demonstrates better visualization and control of the ventral skull base and can overcome the current surgical limits of a single approach. Combination of these 2 minimally invasive approaches should reduce the overall morbidity. Clinical trials are needed to evaluate the virtual applications of this approach.

Rigid, Variable-View Endoscope in Neurosurgery: First Intraoperative Experience.

The endoscope became a highly valued visualization tool in neurosurgery. However, technical limitations caused by the rigidity of current standard endoscopes significantly decrease ergonomy in transcranial neurosurgery. Further technological developments will aid enlarging the surgical applicability. To evaluate the intraoperative features of a rigid variable-view endoscope in neurosurgery. We assessed a 4 mm rigid rod lens endoscope (EndoCAMeleon, Karl Storz, Tuttlingen, Germany) in the intraoperative setting. The device offers a variable angle of view from 15° to 90° in one plane. The endoscope was used in 3 cases (aneurysm clipping, vestibular schwannoma surgery, endoscopic third ventriculostomy) for inspection. Direct insertion of the device through the craniotomy/burr hole with the lowest angled view (15°) was always possible. Neurovascular structures crossing the access route could be visualized and avoided. This allowed a targeted positioning of the endoscope's tip in the operating field. Once the target point was reached, viewing direction was changed in one plane from 15° to 90° according to anatomic demands. As the endoscope's tip does not move while the lens is rotated, surrounding neurovascular structures are not at risk to be injured. However, turning of the lens-controlling wheel in proximity to delicate structures may be inconvenient. The rigid, variable-view endoscope has the potential to become an appreciated visualization tool in neuroendoscopy. The steerable lens enables a tremendous expansion of the visual field, resulting in higher efficiency for surgeons and increased safety for patients.

New endoscopic route to the temporal horn of the lateral ventricle: surgical simulation and morphometric assessment.

The temporal horn of the lateral ventricle is a complex structure affected by specific pathological conditions. Current approaches to the temporal horn involve a certain amount of corticotomy and white matter disruption. Surgeons therefore set aside anterior temporal lobectomy as a last resource and avoid it in the dominant hemisphere. The authors propose a minimally invasive endoscopic intraventricular approach to the temporal horn and describe a standardized analysis and technical assessment of the feasibility of this approach. To determine the best trajectory, angulation, and entry point to the temporal horn of the lateral ventricle, the authors evaluated 50 cranial MRI studies (100 temporal lobes) from healthy patients. They studied and systematized the neurosurgical endoscopic anatomy. They also simulated the proposed approach in 9 cadaveric specimens (18 approaches). Mean scalp entry point coordinates (± SD) were 2.7 ± 0.28 cm lateral to the inion and 5.6 ± 0.41 cm superior to the inion. The mean total distance from the uncal recess to the scalp (± SD) was 10.64 ± 0.6 cm. The mean total intraparenchymal distance crossed by the endoscope was 3.76 ± 0.36 cm. The approach was successfully completed in all studied specimens. In this study, the endoscopic intraventricular approach to the temporal horn is standardized. The morphometric analysis makes this approach anatomically feasible and replicable. This approach provides minimally invasive endoscopic access to the uncal recess, amygdala, hippocampus, fornix, and paraventricular temporal lobe structures. The following essential strategies enabled access to and maneuverability inside the temporal horn: tailored preoperative planning of the trajectory and use of anatomical and radiological references, constant irrigation, and an angled endoscopic lens. Safety assessment and novel instruments and techniques may be proposed to advance this very promising route to pathological changes in the temporal lobe.