A mini-invasive surgical technique for Carlevale IOL implantation: case series study and description of concomitant surgery

Purpose: To examine the feasibility and outcomes of a modified technique for the implantation of scleral fixated Carlevale intraocular lens (IOL) (I71 FIL SSF. Soleko IOL Division, Pontecorvo, Italy), and to analyze the occurrence of adverse events. Methods: This is a retrospective observational study conducted revising patients charts from 2018 to 2023. Thirty-five eyes of 33 patients were included. Patients requiring IOL explantation had either IOL dislocation or opacification. The implantation of the Carlevale IOL was performed with the subconjunctival positioning of the anchors without any scleral flap. All maneuvers were performed transconjunctivally. The anatomical outcomes considered were IOL positioning, and the absence of postoperative complications. The functional outcomes analyzed were best correctedvisual acuity (BCVA) and refraction. Results: In all the cases, the IOL was well positioned and centered postoperatively. No cases of conjunctival erosion were recorded. The best corrected visual acuity (BCVA) was 0.9±0.6 logMar (mean±standard deviation) preoperatively and 0.5±0.5 logMar (mean±standard deviation) postoperatively. The mean preoperative spherical equivalent was +6.8±7.7 dioptres, while postoperatively it was -1.1±1.6 dioptres. The most frequent procedure associated to secondary IOL implantation was posterior vitrectomy (25 eyes, 71.4%), which was performed with 25-gauge transconjunctival cannulas in the ciliary sulcus. The follow-up period was 24.5±16.9 months (mean±standard deviation). Conclusion: The described mini-invasive technique for Carlevale IOL implantation is safe and effective. It can be recommended either as a stand-alone operation or associated to concurrent surgical procedures

Designing a braille reader using the snap buckling of bistable magnetic shells

A design concept is introduced for the building block, a dot, of programmable braille readers utilizing bistable shell buckling, magnetic actuation, and pneumatic loading. The design process is guided by Finite Element simulations, which are initially validated through precision experiments conducted on a scaled-up, single-shell model system. Then, the simulations are leveraged to systematically explore the design space, adhering to the standardized geometric and physical specifications of braille systems. The findings demonstrate the feasibility of selecting design parameters that satisfy both geometric requirements and blocking forces under moderate magnetic fields, facilitated by pneumatic loading to switch between the two stable states. The advantages of the proposed design include the reversible bistability of the actuators and fast state-switching via a transient magnetic field. While the study is focused on experimentally validated numerical simulations, several manufacturing challenges that need to be resolved for future physical implementations are identified

On the development of a new flexible drill for orthopedic surgery and the forces experienced on drilling bovine bone

This article presents the construction of a flexible drill which is designed to cut a curved canal in the bone or remove bone materials, to improve the outcome of orthopedic surgery and to facilitate minimally invasive. This article reports the design of the flexible drill and uses it in an experimental rig to evaluate the drilling force generated when cutting bovine bone. The experiments facilitate the measurement of action forces between the mill bits when moving the tip toward or across a bone sample in various configurations caused by bending the flexible drill sheath to enable cutting of a curved path of variable radius in the bone. The reaction force represents the force trying to deflect the mill bit tip away from the bone sample surface and must be resisted in order to continue cutting without deflection or buckling of the tip during the drilling of curved pathways. The experiment shows the flexible drill can cut bones in both configurations and experienced a maximal force of 3.4N in the vertical configuration and 0.54N in lateral configuration. The experimental results show that the flexible drill designed is able to produce sufficient force at variable bending angles to perform the required tasks for bone cutting

NOViSE: a virtual natural orifice transluminal endoscopic surgery simulator

Purpose: Natural Orifice Transluminal Endoscopic Surgery (NOTES) is a novel technique in minimally invasive surgery whereby a flexible endoscope is inserted via a natural orifice to gain access to the abdominal cavity, leaving no external scars. This innovative use of flexible endoscopy creates many new challenges and is associated with a steep learning curve for clinicians. Methods: We developed NOViSE - the first force-feedback enabled virtual reality simulator for NOTES training supporting a flexible endoscope. The haptic device is custom built and the behaviour of the virtual flexible endoscope is based on an established theoretical framework – the Cosserat Theory of Elastic Rods. Results: We present the application of NOViSE to the simulation of a hybrid trans-gastric cholecystectomy procedure. Preliminary results of face, content and construct validation have previously shown that NOViSE delivers the required level of realism for training of endoscopic manipulation skills specific to NOTES Conclusions: VR simulation of NOTES procedures can contribute to surgical training and improve the educational experience without putting patients at risk, raising ethical issues or requiring expensive animal or cadaver facilities. In the context of an experimental technique, NOViSE could potentially facilitate NOTES development and contribute to its wider use by keeping practitioners up to date with this novel surgical technique. NOViSE is a first prototype and the initial results indicate that it provides promising foundations for further development

Intraocular Lens Tilt Due to Optic-Haptic Junction Distortion Following Intrascleral Haptic Fixation With the Yamane Technique

Purpose: To report two patients with a complication of Yamane intrascleral haptic fixation surgery (ISHF) with the Zeiss CT Lucia 602 lens: severely tilted intraocular lens (IOL) leading to significantly decreased vision in the early post-operative period. Observations: We report two patients presenting with severely tilted IOL implants one day and one month following Yamane ISHF. The first patient is a monocular 81-year-old woman referred for treatment of cornea edema. Initial surgery involved replacement of an anterior chamber lens with a CT Lucia 602 posterior chamber lens using Yamane technique and Descemet\u27s stripping endothelial keratoplasty. The patient returned at one month follow-up with poor vision and IOL tilt observable at the slit lamp through a peripheral iridectomy site. Explanation of the Zeiss lens revealed haptic distortion at the optic-haptic insertion point such that each haptic was about 45° off axis to the plane of the optic in approximately equal and opposite directions. The second patient, a 75-year-old woman, was referred with a completely dislocated lens-bag complex in the right eye. The initial operative treatment for this patient included pars plana vitrectomy, retrieval and removal of the dislocated lens-bag complex, and placement of a Zeiss 602 lens via Yamane ISHF technique. On the first postoperative day, the patient was count fingers in the right eye with an intraocular pressure of 5 mm Hg and obvious IOL tilt on slit lamp examination. Explanation of the lens revealed severely distorted haptics relative to the optic by more than a 60-degree angle on both sides. In both cases, initial surgery was performed with an IOL inspected prior to implantation and found to have normal appearing haptics. At the end of each case, there was adequate centration and no tilt of the IOL. Management in both patients included removal of the defective lens and placement of a new, same power CT Lucia 602 lens via the Yamane technique. Visual acuity improved from CF to 20/30 best corrected after reoperation in both cases. Conclusions and importance: In summary, we describe a complication of Yamane ISHF with the CT Lucia 602 lens in which there is lens tilting associated with distortion at the optic-haptic fastening zone in the early postoperative period. In the event of a titled lens following Yamane ISHF, awareness of this complication may help surgeons consider lens replacement, as the haptics may be permanently distorted or damaged

Inverted curved flexure hinge with torsional reinforcements in a printed prosthetic finger

Flexure-based finger joints for prosthetic hands have been studied, but until now they lack stiffness and load capacity. In this paper we present a design which combines large range of motion, stiffness and load capacity, with a torsional overload protection mechanism. Five design considerations which increase grasp force and limit the stress values are presented: (1) Due to the inverted flexure attachment, the flexures are loaded mainly in tension, avoiding buckling of flexures. (2) Curved flexures have been used of which one straightens out at large deflection angles to improve load capacity at large deflections. (3) To achieve high torsional loads, one of the flexures is outfitted with triangular torsional stiffeners, which increase the out-of-plane stiffness significantly, while only slightly increasing the actuation stiffness. (4) The entire joint is rotated by 20˚ so the combination of actuation and contact forces lead to mainly axial forces in the curved leaf spring, avoiding excessive internal bending. The presented prosthetic flexure-based finger joint is able to achieve 20N of contact force with an additional 5N of out of plane load over the entire 80˚ range of motion, which is a major improvement over existing prosthetic flexure-based finger designs

Frictional contact of soft polymeric shells

The classical Hertzian contact model establishes a monotonic correlation between contact force and area. Here, we showed that the interplay between local friction and structural instability can deliberately lead to unconventional contact behavior when a soft elastic shell comes into contact with a flat surface. The deviation from Hertzian contact first arises from bending within the contact area, followed by the second transition induced by buckling, resulting in a notable decrease in the contact area despite increased contact force. Friction delays both transitions and introduces hysteresis during unloading. However, a high amount of friction suppresses both buckling and dissipation. Different contact regimes are discussed in terms of rolling and sliding mechanisms, providing insights for tailoring contact behaviors in soft shells

Tactile Imaging of an Imbedded Palpable Structure for Breast Cancer Screening

Apart from texture, the human finger can sense palpation. The detection of an imbedded structure is a fine balance between the relative stiffness of the matrix, the object, and the device. If the device is too soft, its high responsiveness will limit the depth to which the imbedded structure can be detected. The sensation of palpation is an effective procedure for a physician to examine irregularities. In a clinical breast examination (CBE), by pressing over 1 cm2 area, at a contact pressure in the 70−90 kPa range, the physician feels cancerous lumps that are 8- to 18-fold stiffer than surrounding tissue. Early detection of a lump in the 5−10 mm range leads to an excellent prognosis. We describe a thin-film tactile device that emulates human touch to quantify CBE by imaging the size and shape of 5−10 mm objects at 20 mm depth in a breast model using ~80 kPa pressure. The linear response of the device allows quantification where the greyscale corresponds to the relative local stiffness. The (background) signal fro