Comparative study of the three-dimensional perception of videos recorded on a "Do it yourself" three-dimensional recording assembly versus the conventional recording system.

PURPOSE: To develop an indigenous "Do it yourself" (DIY) three-dimensional (3D) ophthalmic surgery recording system and validate the perception of stereopsis using it. METHODS: A cross-sectional survey of practicing ophthalmologists with post-postgraduation experience of at least 5 years for perception of stereopsis for three different surgeries was performed; cataract, retinal detachment, and intravitreal drug injection were recorded on DIY assembly, viewed on VRBOX and using laptop videos and pseudo 3 d videos as control. RESULTS: The laptop videos and 3D VR Box videos received higher ratings for stereopsis than the pseudo 3D videos. The parameters that received significantly higher ratings on the 3D VR Box viewing were instrument's position relative to the ocular surface in cataract surgery, anterior chamber depth during capsular staining, ophthalmic visco-surgical device injection, capsulorhexis, phaco tunnel depth, movement of nuclear fragments in the anterior chamber, and intra-ocular lens tilt in the capsular bag during cataract surgery ( P < 0.05). In scleral buckling surgery, the parameters that were significantly rated higher on VR Box were globe contour, separation of the scleral plane from muscle, and explant plane ( P < 0.05). Furthermore, the depth of the needle in the vitreous cavity while administering intravitreal drug injection was also rated significantly higher on VR Box ( P < 0.05). However, the ratings for the depth of corneal incision, depth of scleral incision, overall color, and overall quality were not different statistically when compared between laptop and VR Box viewing. CONCLUSION: DIY 3D recording assembly offers a superior means of appreciating depth at various stages of cataract surgery, scleral buckling, and intravitreal drug injection when compared to laptop viewing and can serve as an effective tool for skill transfer.

Novo gancho muscular milimetrado para cirurgia de estrabismo / A new millimeter muscle hook for strabismus surgery

RESUMO Objetivo: Avaliar um novo tipo de gancho muscular (gancho milimetrado de Felício) e sua eficácia em cirurgias de estrabismo. Métodos: Buscando uma abordagem independente, com a mínima participação do auxiliar, o novo instrumento foi usado em cirurgias de retrocesso e ressecção, para comparar sua eficácia e segurança com a técnica tradicional. Participaram do estudo 14 pacientes divididos em dois grupos. Resultados: O grupo operado por meio da técnica tradicional teve média de idade foi de 14,7 anos, e o grupo que usou o novo gancho teve média de 17 anos. Ambos os grupos obtiveram redução semelhante do estrabismo inicial, sendo, em média, de 87,84% no grupo tradicional e de 93,04% com o novo gancho, porém sem relevância estatística (p=0,274). Conclusão: O gancho milimetrado de Felício mostrou-se opção útil ao cirurgião na realização da cirurgia de estrabismo com redução da importância do auxiliar, de forma segura e reprodutível.

ABSTRACT Objective: To evaluate a new type of muscle hook (Felício's millimeter hook) and its effectiveness in strabismus surgeries. Methods: Seeking an independent approach, with minimal assistance from the assistant, the new instrument was used in retrocession and resection surgeries, to compare its efficacy and safety with the traditional technique. Results: 14 patients participated in the study, divided into two groups. The group who underwent surgery with the traditional technique had a mean age of 14.7 years and the group using the new hook, 17 years. Both groups obtained a similar reduction in initial strabismus, with an average of 87.84% in the traditional group and 93.04% with the new hook, but without statistically significant difference (p=0.274). Conclusion: Felicio's millimeter hook proved to be a useful option for the surgeon in performing strabismus surgery with a reduction in the importance of the assistant, in a safe and reproducible way.

Usability of abattoir-acquired pig eyes for refractive excimer laser research.

The purpose of this study was to elucidate, under which conditions abattoir-acquired pig eyes are suitable for refractive excimer laser experiments. Porcine eyes from tunnel-scalded (n = 5) and tank-scalded (n = 10) pigs were compared to unscalded eyes (n = 5) and to eyes scalded in the laboratory (n = 5). The corneal epithelium was removed before an excimer laser was used to perform a - 8.0 D photoablation. Corneal thickness was measured by optical coherence topography before and after photoablation. The ablation depth was determined with a contour measuring station, the morphology of the ablated areas was characterized by scanning electron microscopy and white-light profilometry. The scalded eyes showed an increase in corneal swelling which gained statistical significance in tank-scalded eyes showing a wedge-shaped opaque stromal lesion in the nasal corneal quadrant. A measurable deterioration of photoablation was only found in tank-scalded eyes that exhibited the opaque lesion. Ablated area morphology was smooth and regular in the unscalded and tunnel-scalded eyes. The tank-scalded eyes showed conspicuous wrinkles. While unscalded eyes should always be preferred for excimer laser laboratory experiments, the data suggest that the use of tunnel-scalded eyes may also be acceptable and should be chosen over tank-scalded eyes.

A Submillimeter Continuous Variable Stiffness Catheter for Compliance Control.

Minimally invasive robotic surgery often requires functional tools that can change their compliance to adapt to the environment and surgical needs. This paper proposes a submillimeter continuous variable stiffness catheter equipped with a phase-change alloy that has a high stiffness variation in its different states, allowing for rapid compliance control. Variable stiffness is achieved through a variable phase boundary in the alloy due to a controlled radial temperature gradient. This catheter can be safely navigated in its soft state and rigidified to the required stiffness during operation to apply a desired force at the tip. The maximal contact force that the catheter applies to tissue can be continuously modified by a factor of 400 (≈20 mN-8 N). The catheter is equipped with a magnet and a micro-gripper to perform a fully robotic ophthalmic minimally invasive surgery on an eye phantom by means of an electromagnetic navigation system.

Comparison of the effects of operating microscopes with light emitting diode and halogen light source on the eye: a rabbit study.

PURPOSE: To evaluate the potential toxicity of operation microscopes with halogen and light emitting diode (LED) light source on the rabbit eyes. MATERIALS AND METHODS: Thirty-two eyes of 16 male New Zealand pigmented rabbits were involved in the study. The rabbits were divided into two groups according to the type of light source applied. Only one eye of each rabbit was exposed to illumination light, unexposed fellow eyes served as the control group. Experimental groups included group 1 exposed to halogen light for 2 h and evaluated 1 day and 1 week after the illumination, group 2 exposed to LED light for two hours and evaluated 1 day and 1 week after the illumination. On the first and seventh days after exposing the light, we evaluated the rabbit corneas using in vivo confocal microscopy (IVCM). At the end of the seventh day, the Hematoxylin-eosin staining and TUNEL staining were performed to investigate the presence of apoptosis in the retina and retina pigment epithelium. RESULTS: Early IVCM findings revealed corneal epithelial cell ovalization and indistinct intercellular borders in the halogen light group. We also observed more increase in the keratocyte density index (23.7% vs 14.1%, p = 0.001, respectively) and the Bowman reflectivity index (12.4% vs 4.1%, p = 0.001, respectively) at first day of the light exposure in halogen light group compared to LED light group. However, late IVCM indicated that these findings disappeared one week later. No apoptosis was observed in the corneal and retinal layers in early and late examination groups. CONCLUSION: The present experimental study demonstrated that both halogen and LED lights, which were commonly used for microscopic eye surgery, had no sustained adverse effect on the cornea and retina of the rabbits; however, halogen light had a temporary adverse effect on corneal epithelium and stroma, which resolved within 1 week.

Clinical experience of using the NGENUITY three-dimensional surgery system in ophthalmic surgical procedures.

PURPOSE: To assess the clinical experience of using a three-dimensional (3D) system for ophthalmic surgical procedures. METHODS: We retrospectively analysed video recordings of patients who underwent 3D ophthalmic surgery, using the NGENUITY® 3D visualization system, or traditional microsurgery at our hospital, from August 2017 to February 2018. Patients underwent phacoemulsification or phacoemulsification combined with vitrectomy. Diagnoses, operation type, duration of continuous curvilinear capsulorhexis (CCC), number of forceps nips during CCC and capsulorhexis complications were recorded. Five surgeons and four assistants answered a 3D surgery questionnaire. RESULTS: Twenty-six of 46 patients who underwent 3D surgery, and 31 of 51 patients who underwent traditional microsurgery (control group) were enrolled. The mean CCC duration in the study and control groups was 31.2 ± 10.8 and 28.7 ± 13.2 seconds (p = 0.071), and the mean number of forceps nips was 5 ± 2 and 5 ± 2 (p = 0.634), respectively. The anterior capsular rupture rate of phacoemulsification under 3D and traditional conditions was 3.85% (1/26 cases) and 3.23% (1/31 cases), respectively. The complication rate was similar between the two groups (p > 0.999). Four of five surgeons and two of four assistants believed the clarity of 3D surgery was similar or better than that of traditional microsurgery. The occurrence of dizziness (p > 0.999), shoulder and neck pain (p = 0.262), backache (p = 0.471) and visual fatigue (p = 0.347) did not differ significantly between the two methods. CONCLUSION: The 3D surgical system facilitated similar operation speed and stability as the traditional microscope and provided reliable support for ophthalmic surgery.

Preclinical Studies of a Novel Microfabricated Device to Treat Corneal Epithelial Disease.

PURPOSE: Anterior stromal puncture is an inexpensive technique for treating recurrent corneal erosions but is often ineffective and cannot be used in the optical axis because of scarring. These studies tested a novel microfabricated imprinting instrument to assess its potential efficacy for the treatment of corneal epithelial disease in the optical axis. METHODS: The device is made using glass rods, bundled and drawn through multiple iterative cycles, and then fused under high heat to generate a solid rod comprised of many parallel, aligned, cladded fibers. The rods are sliced into discs and then etched to yield designable spikes based on the borosilicate composition of the glass. RESULTS: Imprinting the cornea yields a regular pattern of imprints. Histologic studies showed both nonpenetrating stable deformations of Bowman layer, with formation of stable epithelial attachments, and full thickness penetration, with superficial ingrowth of the basal epithelium. CONCLUSIONS: Microimprinted corneal tissue shows focal subepithelial scarring without evidence of optically evident anterior stromal scarring, and may be an effective way of treating recurrent corneal erosions in the optical axis, which is not currently possible using standard anterior stromal puncture methods.

OUTER RETINAL INJURY SECONDARY TO MEMBRANE PEELING WITH INTERNAL LIMITING MEMBRANE FORCEPS.

PURPOSE: To present a case of visually significant retinal injury due to internal limiting membrane (ILM) peeling using ILM forceps alone. METHODS: Case report. RESULTS: A 60-year-old woman who underwent ILM peeling for an epiretinal membrane presented with linear central scotomata. Peeling had been initiated and performed with ILM forceps alone, without the use of other surgical instruments. Fundus examination and spectral domain optical coherence tomography imaging confirmed the presence of several discrete areas of inner and outer retinal injury in the macula, which corresponded to her scotomata. CONCLUSION: This is a case of visually significant retinal injury due to ILM peeling that was performed with ILM forceps alone. Improper peeling technique can transmit injurious forces to the retina. Surgeons must be mindful of the biomechanical forces involved in ILM peeling to minimize traction on the retina.

Novel Microforceps Technique Developed for Endothelial Surgical Procedures.

PURPOSE: To develop a more efficient and less traumatic method of Descemet membrane removal in endothelial surgery. METHODS: A novel, vertically oriented, reverse-grasping microforceps (named the Rabiyah Descemet Membrane Removal Microforceps) were created to facilitate grasping and extraction of a host Descemet membrane. RESULTS: This new instrument has been used successfully and safely in more than 85 endothelial keratoplasty cases among 4 surgeons. CONCLUSIONS: The Rabiyah Descemet Membrane Removal Microforceps provides surgeons with a safe and an efficient option to remove Descemet membrane in endothelial surgical procedures.

Descemet Membrane Endothelial Keratoplasty Using a Pull-Through Technique With Novel Infusion Forceps.

PURPOSE: To describe a surgical technique of Descemet membrane endothelial keratoplasty (DMEK) using an endothelium-in pull-through technique with novel infusion forceps and report 6-month clinical outcomes. METHODS: This is a retrospective case series of 33 cases with Fuchs endothelial corneal dystrophy who underwent either DMEK alone (n = 5), DMEK combined with phacoemulsification (n = 27), or DMEK combined with intraocular lens exchange (n = 1) performed by surgeons at the beginning of the DMEK learning curve. Best-corrected visual acuity (BCVA), manifest refraction, central corneal thickness, endothelial cell density, intraoperative and postoperative complications, and need for additional surgeries including rebubbling were evaluated through 6 months postoperatively. RESULTS: Preoperative BCVA was 0.37 ± 0.34 logarithm of the minimum angle of resolution and improved to 0.09 ± 0.10 logarithm of the minimum angle of resolution at 6 months (P < 0.001). Eighty-two percent of eyes obtained a BCVA of 20/25 or better. Central corneal thickness decreased significantly at 6 months (P < 0.001). Endothelial cell loss was 29.1% at 6 months (available for 20 of 33 eyes). All surgeries were uneventful. Six eyes required rebubbling for graft detachments. There were no primary or secondary graft failures at 6 months. CONCLUSIONS: DMEK with infusion microforceps is efficacious and safe in eyes with Fuchs endothelial corneal dystrophy and could offer a more controlled surgery, making it suitable for both novice and experienced DMEK surgeons.

Murine Corneal Epithelial Wound Modeling.

A murine model of corneal epithelial wounding can be performed using simple injury and imaging methods. Here, we describe the creation of a central corneal epithelial defect using mechanical debridement under ophthalmic microscopic visualization. Subsequent monitoring with vital dye application and slit-lamp bio microscopy (slit-lamp) is described in detail.

Absence of lymphatic vessels in non-functioning bleb capsules of glaucoma drainage devices.

PURPOSE: To evaluate the presence and appearance of blood and lymphatic vessels in non-functioning bleb capsules of glaucoma drainage devices (GDD). MATERIALS AND METHODS: Non-functioning (n=14) GDD-bleb capsules of 12 patients were analyzed by immunohistochemistry for blood vessels (CD31, vascular endothelium), lymphatic vessels (lymphatic vessel endothelial hyaluronan receptor-1 [LYVE-1] and podoplanin) and macrophages (CD68). RESULTS: CD31+++ blood vessels and CD68+ macrophages were detected in the outer layer of all specimens. LYVE-1 immunoreactivity was registered in single non-endothelial cells in 8 out of 14 (57%) bleb capsule specimens. Podoplanin-immunoreactivity was detected in all cases, located in cells and profiles of the collagen tissue network of the outer and/or the inner capsule layer. However, a colocalization of LYVE-1 and podoplanin as evidence for lymphatic vessels was not detected. CONCLUSIONS: We demonstrate the presence of blood-vessels but absence of lymphatic vessels in non-functioning bleb capsules after GDD-implantation. While the absence of lymphatic vessels might indicate a possible reason for drainage device failure, this needs to be confirmed in upcoming studies, including animal experiments.

Long-term follow up of intracorneal ring segment implantation in 932 keratoconus eyes.

PURPOSE: To evaluate the progression of keratoconus in 932 eyes of 659 patients through visual, refractive and topographic data after intracorneal ring segment (ICRS) implantation. METHODS: Retrospective review of 659 patients who underwent ICRS (Intacs®) implantation for keratoconus between September 1997 and November 2017. Demographics, preoperative and postoperative uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) in LogMAR, corneal topography parameters (thinnest pachymetry, Kmax), central corneal pachymetry and total follow-up time were evaluated. Statistical analysis was performed using IBM SPSS Statistics 24.0 for windows. RESULTS: Nine hundred and thirty-two eyes of 659 patients, with a mean age of 30.41 years (range 11-76 years), were evaluated. Mean total follow up time was 3.02 years. Forty-one eyes had a total follow up of over 10 years. Both UCVA and BCVA improved significantly after ICRS implantation (P<0.01). Only 18 eyes (2.66% of eyes of patients under 35 years of age) were found to have progression of keratoconus based on postoperative topographic data (Mean age 23.00 years, 55.6% female, total follow-up 2 to 10 years) CONCLUSION: ICRS implantation showed long-term improvement and stability in visual and topographic results in a large case series of patients with keratoconus. Only a minimal rate of progression was detected in young patients. However, further prospective studies need to be conducted to better define predictability of postoperative visual outcomes and progression.

Clinical outcomes of trabecular microbypass stent (iStent) implantation in medically controlled open-angle glaucoma in the Korean population.

To evaluate the safety and efficacy [intraocular pressure (IOP)-lowering effect and medication use] of a single trabecular microbypass stent (iStent; Glaukos Corp, San Clemente, CA) for medically controlled open-angle glaucoma.This retrospective case series included 42 eyes of 34 patients with medically controlled open-angle glaucoma with IOP less than 21 mm Hg. Clinical outcomes analyzed were IOP, medication use, corrected distance visual acuity (CDVA), and surgical complications. Surgical success was defined according to 4 criteria: IOP < 21 mm Hg without medication; IOP < 18 mm Hg without medication; IOP < 15 mm Hg without medications; and IOP < 18 mm Hg with or without medication. Patients were followed for a minimum of 6 months postoperatively.Mean IOP was reduced from 15.8 ±â€Š2.8 mm Hg to 14.5 ±â€Š2.8 mm Hg (P < .001), while mean number of medications decreased from 2.2 ±â€Š1.2 to 0.8 ±â€Š1.1 at final visit (P < .001). Surgical success rates were 78.6%, 61.9%, 57.1%, and 97.6% at 6 months and 78.6%, 59.5%, 52.4%, and 95.2% at final visits according to criteria A, B, C, and D. Meanwhile, 59.5% of patients were medication-free at their final visit. The relative risk of surgical failure by Criteria B and C was 4.337 (95% confidence interval: 1.799-10.454) and 3.717 (95% confidence interval: 1.516-9.116) times greater in the higher-medication group (3 or more preoperative medications), respectively. CDVA was significantly improved from 0.41 ±â€Š0.10 to 0.09 ±â€Š0.07 LogMAR in the combined phacoemulsification and iStent implantation group (P < .001). There was no case whose vision was threatened (vision loss of 2 or more lines) or who showed severe complications after surgery.Single trabecular microbypass stent implantation was effective in reducing IOP and medication usage in patients with open-angle glaucoma with a low preoperative IOP. Our results imply that it is more difficult to achieve low target IOP control in eyes with higher numbers of preoperative medications.

New retinal tack designs: an analysis of retention forces in human scleral tissue.

PURPOSE: The study aimed to construct a new retinal tack design with high retention forces to prevent spontaneous disentanglement in cases of complicated retinal surgery. METHODS: Six new forms for the peak of a retinal tack were developed using computer-aided design (CAD); then a prototype was produced for each model. Finally, standardised design testing was conducted using human (ex vivo) sclera by logging 15 consecutive measurements for each model. RESULTS: Seven different models underwent pull-out testing (six new models and the original tack model), but two tack models (Model 4, Model 5) failed to penetrate the human tissue. The highest pull-out forces (median) were measured for Model 3, followed by Model 6, Model 2 and Model 1. The original Heimann tack (Model H) was found to have the lowest retention forces. CONCLUSION: The different tack designs altered the penetration and holding forces. The retention forces of the proposed peak design led to a significant increase in the retention forces that were more than twice as high as those in the original Heimann Model.

Management of ophthalmic surgical instruments and processes optimization: mixed method study.

AIM: Analysis of the use of ophthalmic instruments during surgical procedures in order to propose a material management method. METHOD: Mixed method study, sequential exploratory design, performed from January to June 2015, at a university hospital in southern Brazil. First, a qualitative approach was held from brainstorming and field observation. Themes were grouped into thematic categories. By connection, the quantitative stage happened through matrix arrangement and linear programming, culminating in the instrument management proposal. RESULTS: Given categories - instruments reorganization according to the time of the surgical procedure and the need surgical instruments for in each procedure - guided the definition of existing restrictions and application of mathematical models. There was an average reduction of 13.10% in the number of surgical instruments per tray and an increase of 17.88% in surgical production. FINAL CONSIDERATIONS: This proposal allowed the rationalization and optimization of ophthalmic instruments, favoring sustainability of the organization.

Automatic intraoperative optical coherence tomography positioning.

PURPOSE: Intraoperative optical coherence tomography (iOCT) was recently introduced as a new modality for ophthalmic surgeries. It provides real-time cross-sectional information at a very high resolution. However, properly positioning the scan location during surgery is cumbersome and time-consuming, as a surgeon needs both his hands for surgery. The goal of the present study is to present a method to automatically position an iOCT scan on an anatomy of interest in the context of anterior segment surgeries. METHODS: First, a voice recognition algorithm using a context-free grammar is used to obtain the desired pose from the surgeon. Then, the limbus circle is detected in the microscope image and the iOCT scan is placed accordingly in the X-Y plane. Next, an iOCT sweep in Z direction is conducted and the scan is placed to centre the topmost structure. Finally, the position is fine-tuned using semantic segmentation and a rule-based system. RESULTS: The logic to position the scan location on various anatomies was evaluated on ex vivo porcine eyes (10 eyes for corneal apex and 7 eyes for cornea, sclera and iris). The mean euclidean distances (± standard deviation) was 76.7 (± 59.2) pixels and 0.298 (± 0.229) mm. The mean execution time (± standard deviation) in seconds for the four anatomies was 15 (± 1.2). The scans have a size of 1024 by 1024 pixels. The method was implemented on a Carl Zeiss OPMI LUMERA 700 with RESCAN 700. CONCLUSION: The present study introduces a method to fully automatically position an iOCT scanner. Providing the possibility of changing the OCT scan location via voice commands removes the burden of manual device manipulation from surgeons. This in turn allows them to keep their focus on the surgical task at hand and therefore increase the acceptance of iOCT in the operating room.