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International Journal of Laboratory... Aug 2021
Topics: Anemia; Biopsy; Blood Cells; Humans; Sclera; Symptom Assessment
PubMed: 33973735
DOI: 10.1111/ijlh.13568 -
Translational Vision Science &... Sep 2020This study aims to map force interaction between instrument and sclera of in vivo rabbits during retinal procedures, and verify if a robotic active force control could...
PURPOSE
This study aims to map force interaction between instrument and sclera of in vivo rabbits during retinal procedures, and verify if a robotic active force control could prevent unwanted increase of forces on the sclera.
METHODS
Experiments consisted in the performance of intraocular movements of a force sensing instrument, adjacent to the retinal surface, in radial directions, from the center to the periphery and back, and compared manual manipulations with robotic assistance and also robotic assistance with an active force control. This protocol was approved by the Animal Use and Ethical Committee and experiments were according to ARVO Statement of Animal Use.
RESULTS
Mean forces using manual manipulations were 115 ± 51 mN. Using robotic assistance, mean forces were 118 ± 49 mN. Using an active force control method, overall mean forces reduced to 69 ± 15, with a statistical difference compared with other methods ( < 0.001). Comparing intraocular directions, superior sector required higher forces and the force control method reduced differences in forces between users and retained the same force pattern between them.
CONCLUSIONS
Results validate that the introduction of robotic assistance might increase the dynamic interactions between instrument and sclera, and the addition of an active force control method reduces the forces at levels lower than manual manipulations.
TRANSLATIONAL RELEVANCE
All marketing benefits from extreme accuracy and stability from robots, however, redundancy of safety mechanisms during intraocular manipulations, especially on force control and surgical awareness, would allow all utility of robotic assistance in ophthalmology.
Topics: Animals; Microsurgery; Rabbits; Retina; Robotic Surgical Procedures; Robotics; Sclera
PubMed: 32953242
DOI: 10.1167/tvst.9.10.2 -
Ophthalmic Research 2023The aim of this study was to investigate and compare the anterior segment biometrics in high myopia and control groups.
INTRODUCTION
The aim of this study was to investigate and compare the anterior segment biometrics in high myopia and control groups.
METHODS
Thirty-four eyes of 34 high myopia patients and 42 eyes of 42 control subjects were included. Schlemm's canal (SC) area, trabecular meshwork (TM) thickness and length, scleral spur (SS) length, and anterior scleral thickness (AST) were measured using swept-source optical coherence tomography. Associations between SC area, TM thickness, TM length, SS length, and AST were also estimated.
RESULTS
SC area, TM thickness, and SS length were significantly associated with AST0 (AST at 0 mm from SS) in both high myopia and control groups. AST0 (702.61 ± 78.05 vs. 729.12 ± 95.87 μm, p = 0.085) and SS length (206.25 ± 52.25 vs. 212.09 ± 51.86 μm, p = 0.556) were not significantly different between high myopia and control groups, whereas SC area (6,622.68 ± 1,130.06 vs. 6,105.85 ± 1,297.84 μm2, p = 0.015) was significantly greater and TM thickness (96.15 ± 34.40 vs. 107.93 ± 29.97 μm, p = 0.048) was significantly thinner in high myopia group than in control group.
CONCLUSION
SC area and TM thickness were significantly associated with AST0, while AST0 and SS length were not significantly different between high myopia and control groups. The changes in SC and TM dimensions in high myopia eyes might be caused by factors other than AST0 and SS length.
Topics: Humans; Trabecular Meshwork; Sclera; Myopia; Tomography, Optical Coherence; Biometry
PubMed: 35926453
DOI: 10.1159/000526280 -
Ophthalmic & Physiological Optics : the... Jul 2020The sclera plays an important role in the biomechanical stability of the eye. We aimed to examine if changes in the shape of the anterior sclera occur in response to...
PURPOSE
The sclera plays an important role in the biomechanical stability of the eye. We aimed to examine if changes in the shape of the anterior sclera occur in response to accommodation and convergence.
METHODS
Thirty-six healthy young adult participants aged between 18 and 30 years including 18 myopes (-0.5 to -4.0 D) and 18 emmetropes (+0.5 to -0.25 D) were recruited. Eye surface profilometry was used to evaluate the anterior eye surface shape before and during visual tasks involving accommodation (5.0 D demand), simulated convergence (9° demand) and their combination. The changes in the sagittal height and axial radius of curvature of the nasal (n = 25) and temporal (n = 31) corneal periphery and anterior sclera were analysed in those participants with complete and reliable data on these sides.
RESULTS
Significant changes were confined to the nasal anterior scleral surface. A significant forward movement of the surface accompanied accommodation (mean change: 5 ± 2 µm), convergence (19 ± 6 µm), and their combination (16 ± 6 µm). There was flattening with convergence (0.092 ± 0.044 mm) and with the combination of accommodation and convergence (0.201 ± 0.071 mm). The changes in response to accommodation and convergence increased peripherally. Changes were not significantly different between low to moderate myopes and emmetropes.
CONCLUSIONS
Accommodation and simulated convergence affect the nasal anterior scleral shape, with the greatest changes associated with convergence and being most evident in the more peripheral nasal scleral regions.
Topics: Accommodation, Ocular; Adolescent; Adult; Cornea; Emmetropia; Female; Healthy Volunteers; Humans; Male; Sclera; Tomography, Optical Coherence; Young Adult
PubMed: 32495362
DOI: 10.1111/opo.12697 -
Journal of Proteomics Jul 2021Myopia is the most common optical disorder in the world, and wavelength defocus induced ametropia and myopia have attracted great attention. The objective was to...
Myopia is the most common optical disorder in the world, and wavelength defocus induced ametropia and myopia have attracted great attention. The objective was to identify and quantify scleral proteins involved in the response to the wavelength defocus. Guinea pigs were randomly divided into 3 groups that received different lighting conditions for 8 weeks: white light, short wavelength light, and long wavelength light. Refraction and axial length were measured, Hematoxylin-Eosin staining and transmission electron microscope were adopted to observe the scleral structure, and scleral proteome was also detected to analyze protein abundance by employing TMT labeling method. After light stimulation, the long- and short -wavelength light induced myopic and hyperopic effect on the guinea pig's eye and induced distinct protein signature, respectively. 186 dyregulated proteins between the short- and long-wavelength group were identified, which were mainly located in extracellular region and involved in metabolic process. We also found that 5 proteins in the guinea pigs scleras in response to wavelength defocus were also human myopic candidate targets, suggesting functional overlap between dyregulated proteins in scleral upon exposure to wavelength defocus and genes causing myopia in humans. SIGNIFICANCE: Wavelength defocus induces refractive errors and leads to myopia or hyperopia. However, sclera proteomics respond to wavelength defocus is lacking, which is crucial to understanding how wavelength defocus influences refractive development and induces myopia. In this proteome analysis, we identified unique protein signatures response to wavelength defocus in sclera of guinea pigs, identified potential mechanisms contributing to myopia formation, and found that several human myopia-related genes may involve in response to wavelength defocus. The results of this study provide a foundation to understand the mechanisms of myopia and wavelength defocus induced ametropia.
Topics: Animals; Disease Models, Animal; Guinea Pigs; Hyperopia; Myopia; Proteomics; Refraction, Ocular; Sclera
PubMed: 33964483
DOI: 10.1016/j.jprot.2021.104248 -
Current Opinion in Ophthalmology May 2020A variety of techniques exist for secondary intraocular lens (IOL) implantation. Of note, scleral fixated intraocular lenses have become more popular with a variety of... (Review)
Review
PURPOSE OF REVIEW
A variety of techniques exist for secondary intraocular lens (IOL) implantation. Of note, scleral fixated intraocular lenses have become more popular with a variety of techniques, both with and without use of sutures. Herein, we focus on reviewing recently published studies describing the long-term outcomes of scleral fixation techniques.
RECENT FINDINGS
Although initial papers describing novel techniques often report short-term outcomes, several studies have recently described intermediate and long-term outcomes for scleral fixated IOLs, albeit all being retrospective case series. Suture fixation methods with long-term follow-up, up to a minimum of 50 months, report dislocation rates between 0 and 15%. Sutureless scleral fixation techniques have increased in popularity the past several years. Although they appear to have a lower rate of IOL dislocation: several studies have reported 0% and one study 8%. The follow-up period for sutureless scleral fixation technique studies, however, is shorter with most studies reporting follow-up of less than a year. Rates of retinal detachment vary between individual studies, but are similar for both suture fixation and sutureless with the majority of studies reporting a rate between 0 and 5%. These studies show that long-term outcomes are important considerations in surgical decision-making.
SUMMARY
Scleral fixation techniques have shown long-term durability and safety in recent retrospective studies. Comparison of techniques has been limited, and more robust studies may be required to provide stronger anatomic, functional, and comparative data.
Topics: Humans; Lens Implantation, Intraocular; Lenses, Intraocular; Sclera; Suture Techniques
PubMed: 32235250
DOI: 10.1097/ICU.0000000000000661 -
Journal of Autoimmunity Apr 2024Scleritis is a severe and painful ophthalmic disorder, in which a pathogenic role for collagen-directed autoimmunity was repeatedly suggested. We evaluated the presence...
Scleritis is a severe and painful ophthalmic disorder, in which a pathogenic role for collagen-directed autoimmunity was repeatedly suggested. We evaluated the presence of sclera-specific antibodies in a large cohort of patients with non-infectious scleritis. Therefore, we prospectively collected serum samples from 121 patients with non-infectious scleritis in a multicenter cohort study in the Netherlands. In addition, healthy (n = 39) and uveitis controls (n = 48) were included. Serum samples were tested for anti-native human type II collagen antibodies using a validated enzyme-linked immunosorbent assay (ELISA). Further, sclera-specific antibodies were determined using indirect immunofluorescence (IIF) on primate retinal/scleral cryosections. Lastly, human leukocyte antigen (HLA) typing was performed in 111 patients with scleritis. Anti-type II collagen antibodies were found in 13% of scleritis patients, in 10% of healthy controls and in 11% of uveitis controls (p = 0.91). A specific reaction to scleral nerve tissue on IIF was observed in 33% of patients with scleritis, which was higher than in healthy controls (11%; p = 0.01), but similar to uveitis controls (25%; p = 0.36). Reactivity to the scleral nerve tissue was significantly associated with earlier onset of scleritis (48 versus 56 years; p < 0.001), bilateral involvement (65% versus 42%; p = 0.01), and less frequent development of scleral necrosis (5% versus 22%; p = 0.02). HLA-B27 was found to be twice as prevalent in patients with scleritis (15.3%) compared to a healthy population (7.2%). In conclusion, scleral nerve autoantibody reactivity was more common in scleritis and uveitis patients in contrast to healthy controls. Further research is needed to characterize these scleral-nerve directed antibodies and assess their clinical value.
Topics: Animals; Humans; Autoimmunity; Cohort Studies; Sclera; Scleritis; Uveitis
PubMed: 38368769
DOI: 10.1016/j.jaut.2024.103178 -
Journal of Biomechanical Engineering Jun 2022Elevated intraocular pressure (IOP) may cause mechanical injuries to the optic nerve head (ONH) and the peripapillary tissues in glaucoma. Previous studies have reported...
Elevated intraocular pressure (IOP) may cause mechanical injuries to the optic nerve head (ONH) and the peripapillary tissues in glaucoma. Previous studies have reported the mechanical deformation of the ONH and the peripapillary sclera (PPS) at elevated IOP. The deformation of the peripapillary retina (PPR) has not been well-characterized. Here we applied high-frequency ultrasound elastography to map and quantify PPR deformation, and compared PPR, PPS and ONH deformation in the same eye. Whole globe inflation was performed in ten human donor eyes. High-frequency ultrasound scans of the posterior eye were acquired while IOP was raised from 5 to 30 mmHg. A correlation-based ultrasound speckle tracking algorithm was used to compute pressure-induced displacements within the scanned tissue cross sections. Radial, tangential, and shear strains were calculated for the PPR, PPS, and ONH regions. In PPR, shear was significantly larger in magnitude than radial and tangential strains. Strain maps showed localized high shear and high tangential strains in PPR. In comparison to PPS and ONH, PPR had greater shear and a similar level of tangential strain. Surprisingly, PPR radial compression was minimal and significantly smaller than that in PPS. These results provide new insights into PPR deformation in response of IOP elevation, suggesting that shear rather than compression was likely the primary mode of IOP-induced mechanical insult in PPR. High shear, especially localized high shear, may contribute to the mechanical damage of this tissue in glaucoma.
Topics: Elasticity Imaging Techniques; Glaucoma; Humans; Intraocular Pressure; Optic Disk; Sclera
PubMed: 35001106
DOI: 10.1115/1.4053450 -
Investigative Ophthalmology & Visual... Nov 2020Currently, the biomechanical properties of the corneo-scleral limbus when the eye-globe deforms are largely unknown. The purpose of this study is to evaluate changes in...
PURPOSE
Currently, the biomechanical properties of the corneo-scleral limbus when the eye-globe deforms are largely unknown. The purpose of this study is to evaluate changes in elasticity of the cornea, sclera, and limbus when subjected to different intraocular pressures (IOP) using wave-based optical coherence elastography (OCE). Special attention was given to the elasticity changes of the limbal region with respect to the elasticity variations in the neighboring corneal and scleral regions.
METHODS
Continuous harmonic elastic waves (800 Hz) were mechanically induced in the sclera near the corneo-sclera limbus of in situ porcine eye-globes (n = 8). Wave propagation was imaged using a phase-sensitive optical coherence tomography system (PhS-OCT). The eyes were subjected to five different IOP-levels (10, 15, 20, 30, and 40 mm Hg), and spatially distributed propagation velocities were calculated along corneal, limbal, and scleral regions. Finite element analysis (FEA) of the same regions under the same excitation conditions were conducted for further validation of results.
RESULTS
FEA demonstrated that the stiffness of the heterogeneous cornea-limbus-sclera transition can be characterized by phase velocity measurements of the elastic waves produced at 800 Hz in the anterior eye. Experimental results revealed that the wave speed in the limbus (cL = 6.5 m/s) is between the cornea (cc = 2.9 m/s) and sclera (cs = 10.0 m/s) at a physiological IOP level (15 mm Hg) and rapidly increases as the IOP level is increased, even surpassing the wave speed in the sclera. Finally, the change in elastic wave speed in the limbus (ΔcL∼18.5 m/s) was greater than in the cornea (Δcc ∼12.6 m/s) and sclera (Δcs∼8.1 m/s) for the same change in IOP.
CONCLUSIONS
We demonstrated that wave-based OCE can be utilized to assess limbus biomechanical properties. Moreover, experimental evidence showed that the corneo-scleral limbus is highly nonlinear compared to the cornea and sclera when the eye-globe is deformed by an increase of IOP. This may suggest that the limbus has enough structural flexibility to stabilize anterior eye shape during IOP changes.
Topics: Animals; Anterior Eye Segment; Biomechanical Phenomena; Cornea; Elasticity; Elasticity Imaging Techniques; Finite Element Analysis; Intraocular Pressure; Limbus Corneae; Models, Biological; Sclera; Sus scrofa; Tomography, Optical Coherence; Tonometry, Ocular
PubMed: 33141893
DOI: 10.1167/iovs.61.13.7 -
Journal of Visualized Experiments : JoVE Jul 2023Many in vitro models used to investigate tissue function and cell biology require a flow of media to provide adequate oxygenation and optimal cell conditions required...
Many in vitro models used to investigate tissue function and cell biology require a flow of media to provide adequate oxygenation and optimal cell conditions required for the maintenance of function and viability. Toward this end, we have developed a multi-channel flow culture system to maintain tissue and cells in culture and continuously assess function and viability by either in-line sensors and/or collection of outflow fractions. The system combines 8-channel, continuous optical sensing of oxygen consumption rate with a built-in fraction collector to simultaneously measure production rates of metabolites and hormone secretion. Although it is able to maintain and assess a wide range of tissue and cell models, including islets, muscle, and hypothalamus, here we describe its operating principles and the experimental preparations/protocols that we have used to investigate bioenergetic regulation of isolated mouse retina, mouse retinal pigment epithelium (RPE)-choroid-sclera, and cultured human RPE cells. Innovations in the design of the system, such as pumpless fluid flow, have produced a greatly simplified operation of a multi-channel flow system. Videos and images are shown that illustrate how to assemble, prepare the instrument for an experiment, and load the different tissue/cell models into the perifusion chambers. In addition, guidelines for selecting conditions for protocol- and tissue-specific experiments are delineated and discussed, including setting the correct flow rate to tissue ratio to obtain consistent and stable culture conditions and accurate determinations of consumption and production rates. The combination of optimal tissue maintenance and real-time assessment of multiple parameters yields highly informative data sets that will have great utility for research in the physiology of the eye and drug discovery for the treatment of impaired vision.
Topics: Mice; Humans; Animals; Retinal Pigment Epithelium; Cells, Cultured; Choroid; Sclera; Biological Transport
PubMed: 37522735
DOI: 10.3791/65399