Search

Abstract To provide quantitative feedback on surgical progress to ophthalmologists practicing inner limiting membrane (ILM) peeling, we developed an artificial eye module comprising a quartz crystal resonator (QCR) force sensor and a strain body that serves as a uniform force transmitter beneath a retinal model. Although a sufficiently large initial force must be loaded onto the QCR force sensor assembly to achieve stable contact with the strain body, the highly sensitive and wide dynamic-range property of this sensor enables the eye module to detect the slight forceps contact force. A parallel-plate strain body is used to achieve a uniform force sensitivity over the 4-mm-diameter ILM peeling region. Combining these two components allowed for a measurable force range of 0.22 mN to 29.6 N with a sensitivity error within −11.3 to 4.2% over the ILM peeling area. Using this eye module, we measured the applied force during a simulation involving artificial ILM peeling by an untrained individual and compensated for the long-term drift of the obtained force data using a newly developed algorithm. The compensated force data clearly captured the characteristics of several types of motion sequences observed from video recordings of the eye bottom using an ophthalmological microscope. As a result, we succeeded in extracting feature values that can be potentially related to trainee skill level, such as the mean and standard deviation of the pushing and peeling forces, corresponding, in the case of an untrained operator, to 122.6 ± 95.2 and 20.4 ± 13.2 mN, respectively.

Among increasing eye diseases, glaucoma may hurt the optic nerves and lead to vision loss, the treatment of which is to reduce intraocular pressure (IOP). In this research, we introduce a new concept of the surgery simulator for Minimally Invasive Glaucoma Surgery (MIGS). The concept is comprised of an anterior eye model and a fluidic circulatory system. The model made of flexible material includes a channel like the Schlemm’s canal (SC) and a membrane like the trabecular meshwork (TM) covering the SC. The system can monitor IOP in the model by a pressure sensor. In one of the MIGS procedures, the TM is cleaved to reduce the IOP. Using the simulator, ophthalmologists can practice the procedure and measure the IOP. First, considering the characteristics of human eyes, we defined requirements and target performances for the simulator. Next, we designed and manufactured the prototype. Using the prototype, we measured the IOP change before and after cleaving the TM. Finally, we demonstrated the availability by comparing experimental results and target performances. This simulator is also expected to be used for evaluations and developments of new MIGS instruments and ophthalmic surgery robots in addition to the surgical training of ophthalmologists.

The present study was performed to establish a novel ocular surgery simulator for training in peeling of the inner limited membrane (ILM). This simulator included a next-generation artificial ILM with mechanical properties similar to the natural ILM that could be peeled underwater in the same manner as in actual surgery. An artificial eye consisting of a fundus and eyeball parts was fabricated. The artificial eye was installed in the eye surgery simulator. The fundus part was mounted in the eyeball, which consisted of an artificial sclera, retina, and ILM. To measure the thickness of the fabricated ILM on the artificial retina, we calculated the distance of the step height as the thickness of the artificial ILM. Two experienced ophthalmologists then assessed the fabricated ILM by sensory evaluation. The minimum thickness of the artificial ILM was 1.9 ± 0.3 μm (n = 3). We were able to perform the peeling task with the ILM in water. Based on the sensory evaluation, an ILM with a minimum thickness and 1000 degrees of polymerization was suitable for training. We installed the eye model on an ocular surgery simulator, which allowed for the performance of a sequence of operations similar to ILM peeling. In conclusion, we developed a novel ocular surgery simulator for ILM peeling. The artificial ILM was peeled underwater in the same manner as in an actual operation.

The ability to sense force in surgery is in high demand in many applications such as force feedback in surgical robots and remote palpation (e.g., tumor detection in endoscopic surgery). In addition, recording and analyzing surgical data is of substantial value in terms of evidence-based medicine. However, force sensing in surgery remains challenging because of the specific requirements of surgical instruments, namely, they must be small, bio-compatible, sterilizable, and tolerant to noise. In this study, we propose a modular optic force sensor using a Fabry−Perot interferometer that can be used on surgical devices. The the proposed sensor can be implemented like a strain gauge, which is widely used in industrial applications but not compatible with surgery. The proposed sensor includes two key elements, a fiber-optic pressure sensor using a Fabry−Perot interferometer that was previously developed by one of the authors and a structure that includes a carbide pin that contacts the pressure sensor along the long axis. These two elements are fixed in a guide channel fabricated in a 3 × 2 × 0.5 mm sensor housing. The experimental results are promising, revealing a linear relationship between the output and the applied load while showing a linear temperature characteristic that suggests temperature compensation will be needed in use.

Three-dimensional (3D) microfluidic channels, which simulate human tissues such as blood vessels, are useful in surgical simulator models for evaluating surgical devices and training novice surgeons. However, animal models and current artificial models do not sufficiently mimic the anatomical and mechanical properties of human tissues. Therefore, we established a novel fabrication method to fabricate an eye model for use as a surgical simulator. For the glaucoma surgery task, the eye model consists of a sclera with a clear cornea; a 3D microchannel with a width of 200−500 µm, representing the Schlemm’s canal (SC); and a thin membrane with a thickness of 40−132 µm, representing the trabecular meshwork (TM). The sclera model with a clear cornea and SC was fabricated by 3D molding. Blow molding was used to fabricate the TM to cover the inner surface of the sclera part. Soft materials with controllable mechanical behaviors were used to fabricate the sclera and TM parts to mimic the mechanical properties of human tissues. Additionally, to simulate the surgery with constraints similar to those in a real operation, the eye model was installed on a skull platform. Therefore, in this paper, we propose an integration method for fabricating an eye model that has a 3D microchannel representing the SC and a membrane representing the TM, to develop a glaucoma model for training novice surgeons.

Objectives. To evaluate the abdominal visceral fat area (VFA), we developed novel ultrasonographic (US) methods for estimating. Methods. 100 male volunteers were recruited, and their VFA was calculated by two novel US methods, the triangle method and the ellipse method. The VFA calculated by these methods was compared with the VFA calculated by CT. Results. Both the VFA calculated by the triangle method (r=0.766, p

For additional functionality of artificial knee joint, the kinematics of knee has been evaluated using 2D/3D image registration technique after total knee arthroplasty. To evaluate the knee kinematics of implant, it is important how to adjust the ligament balancing around knee joint during surgery. In the kinematics evaluation of image matching, it is difficult to feed back the ligament balancing of knee because the information from image matching will be available after surgery only. Therefore, we developed a CT-based navigation system with the function of measurement of knee motion during surgery, which has been normally applied to enhance the accuracy of implant setting for target bone. The kinematics of knee has been evaluated with position of implant setting and ligament balancing which were obtained by this system during surgical operation. As a result, (1) The knee kinematics showed different trends between bone and implant based coordinate system, (2) Increasing 2mm thickness of insert between femoral and tibia component of artificial knee joint, the anterior-posterior shift of implant with knee flexion was decreased by changing the ligament tension around knee joint. In conclusion, it is possible to measure the knee kinematics with consideration of ligament balancing using the developed navigation system during surgery.

PURPOSE: To elucidate the merits of robotic application for vitreoretinal maneuver in comparison to conventional manual performance using an in-vitro eye model constructed for the present study. METHODS: Capability to accurately approach the target on the fundus, to stabilize the manipulator tip just above the fundus, and to perceive the contact of the manipulator tip with the fundus were tested. The accuracies were compared between the robotic and manual control, as well as between ophthalmologists and engineering students. RESULTS: In case of manual control, ophthalmologists were superior to engineering students in all the 3 test procedures. Robotic assistance significantly improved accuracy of all the test procedures performed by engineering students. For the ophthalmologists including a specialist of vitreoretinal surgery, robotic assistance enhanced the accuracy in the stabilization of manipulator tip (from 90.9 µm to 14.9 µm, P = 0.0006) and the perception of contact with the fundus (from 20.0 mN to 7.84 mN, P = 0.046), while robotic assistance did not improve pointing accuracy. CONCLUSIONS: It was confirmed that telerobotic assistance has a potential to significantly improve precision in vitreoretinal procedures in both experienced and inexperienced hands.