Model eye tool for retinal optical coherence tomography instrument calibration

Optical coherence tomography(OCT)has been extensively used as noninvasive tool for biological tissues owing to its three-dimensional imaging ability and high axial resolution.OCT quality assurance is vital in these occasions to keep the reliability and accuracy in medical diagnosis.It is necessary to develop a calibration tool for OCT product manufacture,calibration,and quality control.A practical tool is demanded in the OCT quality control and calibration of OCT.So far,there is no such a practical tool that can test all the key parameters of OCT.We design and fabricate a model eye tool,which has this function.The model eye comprises a doublet lens,a single filament,a piece of glass plate and the microsphere-embedded phantom.The doublets lens is bonded by two pieces of planoconvex lenses in the plane position.The first lens focuses parallel light onto the rear surface of the second lens.The rear surface marked with concentric circles serves as retina to measure the angular field of view(FOV).The small flat surface on the peak of the second lens is used to test signal to noise ratio(SNR).The single filament with 125μm diameter is used to check the co-alignment of preview and OCT scan.The empty chamber between the small plane of the second lens and the first surface of glass plate is used to measure the depth scaling of the OCT.The microspheres of 1μm diameter distributed uniformly in the phantom,which can test the lateral and the axial resolution of OCT equipment.Experimental results are presented to show the validity of the proposed tool.It is shown that the tool is able to be used in the calibration and quality control of retinal OCT.

Eye Movement Modeling Examples as a Teaching Tool for Epidural Block

Introduction: Video examples with task demonstrations by experts, with the expert’s eye movements superimposed on the task, are known as “eye movement modeling examples” (EMME). We performed this study to evaluate if there were improvements in the performance of anesthesia novice trainees when executing the epidural technique after an EMME of epidural block procedure. Methods: We developed an eye movement modeling example (EMME) from eye tracking recordings made by experienced anesthesiologists with more than 20 years of experience. Forty-two PGY3 anesthesia trainees who had never previously performed an epidural block were randomized to receive (study group) or not receive (control group) the EMME video before their institutional training. All the trainees were evaluated every 10 epidural blocks until the end of the rotation period, by an independent, blinded observer using the Global Rating Scale for Epidural Anesthesia (GRS). Results: Trainees who received the EMME training exhibited more respect for the patient’s tissues (P Discussion: This is the first study that has used the EMME for a practical, clinical teaching purpose on real patients and that has used it as an aid in teaching epidural anesthesia. We demonstrated that inexperienced trainees who received the EMME training improved their proficiency at epidural blocks as compared to those who had no EMME training beforehand. Given this result, we welcome further studies to investigate the impact and the role of EMME on clinical teaching in the field of anesthesia.

Vitreoretinal surgical training-assessment of simulation,models,and rubrics-a narrative review

Background and Objective:Vitreoretinal surgery requires fine micro-surgical training and handling of delicate tissue.To aid in the training of residents and fellows,unique educational modalities exist to help facilitate the development of these microsurgical skills.From virtual simulators to artificial eye models,simulation of the posterior segment has gained an increased focus in vitreoretinal surgical training programs.Development of surgical curricula for vitreoretinal training and attainment of surgical milestones has been a key component in integrating these educational training modalities.We will explore various simulators,eye models,and potential rubrics and discuss unique ways each may help and complement one another to train future vitreoretinal surgeons.Methods:We conducted a systematic PubMed search of various review studies(from publications in English ranging from January 1978 to December 2020)discussing surgical simulators,eye models,and surgical rubrics for vitreoretinal surgery and their potential impacts upon training.Key Contents and Findings:Our review assesses the benefits and applicability of various simulators,eye models,and surgical rubrics upon training.Conclusions:Utilization of vitreoretinal surgical training tools may aid in complementing the hands-on surgical training experience for vitreoretinal surgical fellows.By using simulators and rubrics,we may better be able to standardize training for reaching vitreoretinal surgical milestones and providing adequate feedback to improve surgical competency and ultimately patient outcomes.

Age related macular degeneration: from evidence based-care to experimental models

To describe the current aging population in China and globally,especially as it applies to age-related macular degeneration(AMD).To review the current standards of care for treating both wet(exudative)eAMD and dry(atrophic)aAMD.And to introduce a model for experimentation that is based on the Age-Related Eye Disease Study(AREDS)using eye bank tissue.A literature search that outlines current aging populations,standards of clinical treatment as defined by large,multicenter,randomized clinical trials that present level-I data with a low risk for bias.An experimental model system of AMD is presented that enables scientific analysis of AMD pathogenesis by applying grading criteria from the AREDS to human eye bank eyes.Analysis includes proteomic,cellular,and functional genomics.The standard of care for the treatment of eAMD is currently defined by the use of several anti-vascular endothelial growth(anti-VEGF)agents alone or in combination with photodynamic therapy.Monotherapy treatment intervals may be monthly,as needed,or by using a treat-and-extend(TAE)protocol.There are no proven therapies for aAMD.AMD that is phenotypically defined at AREDS level 3,should be managed with the use of anti-oxidant vitamins,lutein/zeaxanthin and zinc(AREDS-2 formulation).By understanding the multiple etiologies in the pathogenesis of AMD(i.e.,oxidative stress,inflammation,and genetics),the use of human eye bank tissues graded according to the Minnesota Grading System(MGS)will enable future insights into the pathogenesis of AMD.Initial AMD management is with lifestyle modification such as avoiding smoking,eating a healthy diet and using appropriate vitamin supplements(AREDS-2).For eAMD,anti-VEGF therapies using either pro re nata(PRN)or TAE protocols are recommended,with photodynamic therapy in appropriate cases.New cellular information will direct future,potential therapies and these will originate from experimental models,such as the proposed eye bank model using the MGS,that leverages the prospective AREDS database.

Research of bright pupil effect based on Chinese human eye model

An optical model of bright pupil effect based on Chinese human eye model is presented. The effects of the incident rays angle and the size of pupil on bright pupil effect are analyzed theoretically. For the incident rays with 5°–15° field of view, the spot diagram of emergent light is also presented. With the pupil diameters of 3–8 mm, the intensity distributions formed by emergent light are calculated. The optical model of bright pupil effect based on Chinese human eye provides a suitable model for the related further research studies and applications on bright pupil effect with Chinese eye.

Using the traditional model to evaluate the active force of the human lateral rectus muscle

The information on the force of extraocular muscles(EOMs)is beneficial for strabismus diagnosis and surgical planning,and a direct and simple method is important for surgeons to obtain these forces.Based on the traditional model,a numerical simulation method was proposed to achieve this aim,and then the active force of the lateral rectus(LR)muscle was successfully simulated when the eye rotated every angle from 0°to 30°in the horizontal plane from the nasal to the temporal side.In order to verify these simulations,the results were compared with the previous experimental data.The comparison shows that the simulation results diverged much more than the experimental data in the range of 0°–10°.The errors were corrected to make the simulation results closer to the experimental data.Finally,a general empirical equation was proposed to evaluate the active force of the LR muscle by fitting these data,which represent the relationship between the simulation forces and the contractive amounts of the LR muscle.

Modelling ocular ageing in adults with well-controlled type I diabetes

Purpose:To develop a paraxial eye model based on a previously collected cohort of adults with well-controlled type 1 diabetes mellitus(DM1)and a limited range of refractive errors.Methods:The study used the previously published biometric data of 72 participants(Age:41.5
12.4 years)with DM1.Measurements included objective refraction,anterior and posterior corneal radii of curvatures,and internal distances.Moreover,phakometry was used to determine the lens radii of curvature and lens equivalent indices,from which the lens powers were calculated.A multivariate linear regression was performed for each biometric parameter with respect to current age(Age),the time since the onset of diabetes(Tdb),and current levels of glycated hemoglobin(HbA1c).The vitreous chamber depth was determined from other distances,and lens equivalent index was chosen to balance the models.These were compared with an existing model for nondiabetic eyes.Results:Some dependent parameters were not affected by the independent variables(spherical equivalent,anterior corneal radius of curvature,central corneal thickness),some were affected by time since onset(the lens radii of curvatures,anterior chamber depth)and others were affected by both age and time since onset(posterior corneal radius of curvature,lens thickness,axial length).None of the dependent parameters were affected by current levels of HbA1c.Conclusions:The proposed model accurately describes the age-related changes in the eyes of people with DM1.In this description the age of diabetes onset plays an important role,especially if the diabetes onset occurred during childhood.

Correction-free remotely scanned two-photon in vivo mouse retinal imaging

Non-invasive fluorescence retinal imaging in small animals is an important requirement for an array of translational vision applications.The in vivo two-photon imaging of the mouse retina may enable the long-term investigation of the structure and function of healthy and diseased retinal tissue.However,to date,this has only been possible using relatively complex adaptive-optics systems.Here,the optical modeling of the murine eye and of the imaging system is used to achieve correction-free two-photon microscopy through the pupil of a mouse eye to yield high-quality,optically sectioned fundus images.By remotely scanning the focus using an electronically tunable lens,high-resolution three-dimensional fluorescein angiograms and cellular-scale images are acquired,thus introducing a correction-free baseline performance level for two-photon in vivo retinal imaging.Moreover,the system enables functional calcium imaging of repeated retinal responses to light stimulation using the genetically encoded indicator,GCaMP6s.These results and the simplicity of the new add-on optics are an important step toward several structural,functional,and multimodal imaging applications that will benefit from the tight optical sectioning and the use of near-infrared light.