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FASEB Journal : Official Publication of... Apr 2020The optics of the eye is the key to a functioning visual system. The exact nature of the correlation between ocular optics and eye development is not known because of...
The optics of the eye is the key to a functioning visual system. The exact nature of the correlation between ocular optics and eye development is not known because of the paucity of knowledge about the growth of a key optical element, the eye lens. The sophisticated optics of the lens and its gradient of refractive index provide the superior optical quality that the eye needs and which, it is thought, has a major influence on the development of proper visual function. The nature of a gradient refractive index lens, however, renders accurate measurements of its development difficult to make and has been the reason why the influence of lens growth on visual function remains largely unknown. Novel imaging techniques have made it possible to investigate growth of the eye lens in the zebrafish. This study shows measurements using X-ray Talbot interferometry of three-dimensional gradient index profiles in eye lenses of zebrafish from late larval to adult stages. The zebrafish lens shows evidence of a gradient of refractive index from the earliest stages measured and its growth suggests an apparent coincidence between periods of rapid increase in refractive index in the lens nucleus and increased expression of a particular crystallin protein group.
Topics: Animals; Cornea; Lens, Crystalline; Mathematical Computing; Optics and Photonics; Refractometry; Zebrafish
PubMed: 32103543
DOI: 10.1096/fj.201902607R -
Clinical & Experimental Optometry May 2019Optical coherence tomography angiography (OCT-A) is an emerging technology that allows for the non-invasive imaging of the ocular microvasculature. Despite the wealth of... (Review)
Review
Optical coherence tomography angiography (OCT-A) is an emerging technology that allows for the non-invasive imaging of the ocular microvasculature. Despite the wealth of observations and numerous research studies illustrating the potential clinical uses of OCT-A, this technique is currently rarely used in routine clinical settings. In this review, technical and clinical aspects of OCT-A imaging are discussed, and the future clinical potential of OCT-A is considered. An understanding of the basic principles and limitations of OCT-A technology will better inform clinicians of its future potential in the diagnosis and management of ocular diseases.
Topics: Angiography; Diagnostic Techniques, Ophthalmological; Eye; Forecasting; Humans; Microvessels; Tomography, Optical Coherence
PubMed: 30537233
DOI: 10.1111/cxo.12854 -
Indian Journal of Ophthalmology Jun 2022Traditional methods for neuroretinal rim width measurement in spectral domain optical coherence tomography (SD-OCT) employs the Bruch's membrane opening (BMO) as the...
BACKGROUND
Traditional methods for neuroretinal rim width measurement in spectral domain optical coherence tomography (SD-OCT) employs the Bruch's membrane opening (BMO) as the anatomical border of the rim, referenced to a BMO horizontal reference plane, termed as "Bruch's Membrane Opening-Horizontal Rim Width" (BMO-HRW). BMO-HRW is defined as the distance between BMO and internal limiting membrane (ILM) on the horizontal plane. In contrast, the Spectralis OCT (Heidelberg Engineering, Germany) employs a new parameter called "Bruch's Membrane Opening-Minimum Rim Width" (BMO-MRW) with Glaucoma Module Premium Edition (GMPE). GMPE provides a novel objective method of optic nerve head (ONH) analysis using BMO, but the neuroretinal rim assessment is performed from the BMO to the nearest point on the ILM, rather than on the horizontal reference plane. It is the BMO-MRW and is defined as the minimum distance between the BMO and ILM in the ONH.
PURPOSE
In this video, anatomy of the ONH and GMPE is decoded from a neophyte user's point of view, as to why BMO-MRW is more important than the traditional BMO-HRW for glaucoma evaluation.
SYNOPSIS
The GMPE concepts are depicted in a novel dynamic (Clinical vs OCT Vs Histology) screenplay, detailing the below focal points with 2D & 3D animations: True Margin of ONH, Bruch's Membrane (BM), Histology Vs OCT, BMO, Bruch's Membrane Opening-Minimum Rim Width, Bruch's Membrane Opening-Minimum Rim Width Versus Bruch's Membrane Opening-Horizontal Rim Width, Alpha, Beta, Gamma Zone of ONH in OCT, Anatomic Positioning System, Impact of Fovea Bruch's Membrane Opening Centre Axis.
HIGHLIGHTS
This video also highlights, how with the advent of Anatomic Positioning System, scans were able to align relative to the individual's Fovea-to-BMO-center (FoBMOC) axis at every follow-up, for accurately detecting changes, as small as 1 micron in BMO-MRW, thus creating a new world in diagnosing glaucoma and detecting glaucomatous progression with precision.
VIDEO LINK
https://youtu.be/6RqF5guAziw.
Topics: Bruch Membrane; Glaucoma; Humans; Intraocular Pressure; Optic Disk; Retinal Ganglion Cells
PubMed: 35648032
DOI: 10.4103/ijo.IJO_1261_21 -
Eye (London, England) Feb 2017Blindness afflicts ~39 million people worldwide. Retinal ganglion cells are unable to regenerate, making this condition irreversible in many cases. Whole-eye... (Review)
Review
Blindness afflicts ~39 million people worldwide. Retinal ganglion cells are unable to regenerate, making this condition irreversible in many cases. Whole-eye transplantation (WET) provides the opportunity to replace diseased retinal ganglion cells, as well as the entire optical system and surrounding facial tissue, if necessary. Recent success in face transplantation demonstrates that this may be a promising treatment for what has been to this time an incurable condition. An animal model for WET must be established to further enhance our knowledge of nerve regeneration, immunosuppression, and technical aspects of surgery. A systematic review of the literature was performed to evaluate studies describing animal models for WET. Only articles in which the eye was completely enucleated and reimplanted were included. Study methods and results were compared. In the majority of published literature, WET can result in recovery of vision in cold-blooded vertebrates. There are a few instances in which mammalian WET models demonstrate survival of the transplanted tissue following neurovascular anastomosis and the ability to maintain brief electroretinogram activity in the new host. In this study we review in cold-blooded vertebrates and mammalian animal models for WET and discuss prospects for future research for translation to human eye transplantation.
Topics: Animals; Blindness; Disease Models, Animal; Eye; Optic Nerve Injuries; Organ Transplantation; Retina; Tissue Survival
PubMed: 27983731
DOI: 10.1038/eye.2016.272 -
Biomedical Engineering Online Jul 2022Ocular diseases are closely related to the physiological changes in the eye sphere and its contents. Using biomechanical methods to explore the relationship between the... (Review)
Review
Ocular diseases are closely related to the physiological changes in the eye sphere and its contents. Using biomechanical methods to explore the relationship between the structure and function of ocular tissue is beneficial to reveal the pathological processes. Studying the pathogenesis of various ocular diseases will be helpful for the diagnosis and treatment of ocular diseases. We provide a critical review of recent biomechanical analysis of ocular diseases including glaucoma, high myopia, and diabetes. And try to summarize the research about the biomechanical changes in ocular tissues (e.g., optic nerve head, sclera, cornea, etc.) associated with those diseases. The methods of ocular biomechanics research in vitro in recent years are also reviewed, including the measurement of biomechanics by ophthalmic equipment, finite element modeling, and biomechanical analysis methods. And the preparation and application of microfluidic eye chips that emerged in recent years were summarized. It provides new inspiration and opportunity for the pathogenesis of eye diseases and personalized and precise treatment.
Topics: Biomechanical Phenomena; Cornea; Finite Element Analysis; Glaucoma; Humans; Intraocular Pressure; Optic Disk; Sclera
PubMed: 35870978
DOI: 10.1186/s12938-022-01019-1 -
Middle East African Journal of... 2015Potential errors and complications during examination and treatment of strabismic patients can be reduced by recognition of certain optical issues. This articles reviews... (Review)
Review
Potential errors and complications during examination and treatment of strabismic patients can be reduced by recognition of certain optical issues. This articles reviews basic as well as guiding principles of prism optics and optics of the eye to equip the reader with the necessary know-how to avoid pitfalls that are commonly encountered when using prisms to measure ocular deviations (e.g., during cover testing), and when observing the corneal light reflex to estimate ocular deviations (e.g., during Hirschberg or Krimsky testing in patients who do not allow for cover testing using prisms).
Topics: Blinking; Cornea; Eyeglasses; Humans; Lens, Crystalline; Strabismus
PubMed: 26180462
DOI: 10.4103/0974-9233.159691 -
Medical Science Monitor : International... Dec 2023Visualization of the retinal structure is crucial for understanding the pathophysiology of ophthalmic diseases, as well as for monitoring their course and treatment... (Review)
Review
Visualization of the retinal structure is crucial for understanding the pathophysiology of ophthalmic diseases, as well as for monitoring their course and treatment effects. Until recently, evaluation of the retina at the cellular level was only possible using histological methods, because the available retinal imaging technology had insufficient resolution due to aberrations caused by the optics of the eye. Adaptive optics (AO) technology improved the resolution of optical systems to 2 µm by correcting optical wave-front aberrations, thereby revolutionizing methods for studying eye structures in vivo. Within 25 years of its first application in ophthalmology, AO has been integrated into almost all existing retinal imaging devices, such as the fundus camera (FC), scanning laser ophthalmoscopy (SLO), and optical coherence tomography (OCT). Numerous studies have evaluated individual retinal structures, such as photoreceptors, blood vessels, nerve fibers, ganglion cells, lamina cribrosa, and trabeculum. AO technology has been applied in imaging structures in healthy eyes and in various ocular diseases. This article aims to review the roles of AO imaging in the diagnosis, management, and monitoring of age-related macular degeneration (AMD), diabetic retinopathy (DR), glaucoma, hypertensive retinopathy (HR), central serous chorioretinopathy (CSCR), and inherited retinal diseases (IRDs).
Topics: Humans; Retina; Ophthalmoscopy; Tomography, Optical Coherence; Diabetic Retinopathy; Central Serous Chorioretinopathy
PubMed: 38044597
DOI: 10.12659/MSM.941926 -
International Journal of Molecular... Mar 2022Sex hormones are molecules produced by the gonads and to a small extent by the adrenal gland, which not only determine the primary and secondary sexual characteristics... (Review)
Review
Sex hormones are molecules produced by the gonads and to a small extent by the adrenal gland, which not only determine the primary and secondary sexual characteristics of an individual, differentiating man from woman, but also participate in the functioning of the various systems of the body. The evidence that many eye diseases differ in terms of prevalence between men and women has allowed us, in recent years, to carry out several studies that have investigated the association between sex hormones and the pathophysiology of eye tissues. Specific receptors for sex hormones have been found on the lacrimal and meibomian glands, conjunctiva, cornea, lens, retina, and choroid. This work summarizes the current knowledge on the role that sex hormones play in the pathogenesis of the most common ocular disorders and indicates our clinical experience in these situations. The aim is to stimulate an interdisciplinary approach between endocrinology, neurology, molecular biology, and ophthalmology to improve the management of these diseases and to lay the foundations for new therapeutic strategies.
Topics: Conjunctiva; Cornea; Eye Diseases; Female; Gonadal Steroid Hormones; Humans; Lacrimal Apparatus; Male; Meibomian Glands
PubMed: 35328690
DOI: 10.3390/ijms23063269 -
Asia-Pacific Journal of Ophthalmology... 2016Open-angle glaucoma (OAG) is characterized by optic nerve fiber atrophy and deterioration of the visual field, corresponding to damage to the optic nerve head.... (Review)
Review
Open-angle glaucoma (OAG) is characterized by optic nerve fiber atrophy and deterioration of the visual field, corresponding to damage to the optic nerve head. Intraocular pressure (IOP) is currently the only evidence-based, treatable risk factor for OAG. However, normal-tension glaucoma, the most common type of OAG in Asia, is a type of glaucoma with an unclear pathogenesis. Glaucoma is suspected to be a multifactorial disease with IOP-dependent and IOP-independent risk factors, including decreased ocular blood flow (OBF), oxidative stress, decreased axoplasmic flow, and genetic background. A number of epidemiological studies have generated strong evidence that OBF may be an especially important risk factor for the progression of glaucoma. Recent innovations in laser speckle flowgraphy and optical coherence tomography-based angiography have allowed us to noninvasively monitor changes in the microcirculation of the optic nerve head with high reproducibility. Laser speckle flowgraphy-derived measurement parameters include mean blur rate and pulse wave form parameters, whereas the main optical coherence tomography angiography-derived parameter is the vessel index. Decreases in these parameters are associated with the severity of glaucomatous damage, and changes are detectible even in the earliest, preperimetric stage of glaucoma. In the future, OBF analysis may improve significantly because of continuing progress in the development of the relevant instruments. This review will summarize possible connections between systemic and OBF abnormalities and OAG, describe the scientific rationale for these connections, and discuss their potential implications. Thus, this review will summarize the role of OBF in glaucoma pathogenesis and discuss the wide range of IOP-independent risk factors.
Topics: Blood Pressure; Eye; Glaucoma, Open-Angle; Humans; Intraocular Pressure; Optic Disk; Oxidative Stress; Regional Blood Flow; Reproducibility of Results; Retinal Vessels; Risk Factors
PubMed: 26886118
DOI: 10.1097/APO.0000000000000183 -
Developmental Biology Aug 2021The basic structure of the eye, which is crucial for visual function, is established during the embryonic process of optic cup morphogenesis. Molecular pathways of... (Review)
Review
The basic structure of the eye, which is crucial for visual function, is established during the embryonic process of optic cup morphogenesis. Molecular pathways of specification and patterning are integrated with spatially distinct cell and tissue shape changes to generate the eye, with discrete domains and structural features: retina and retinal pigment epithelium enwrap the lens, and the optic fissure occupies the ventral surface of the eye and optic stalk. Interest in the underlying cell biology of eye morphogenesis has led to a growing body of work, combining molecular genetics and imaging to quantify cellular processes such as adhesion and actomyosin activity. These studies reveal that intrinsic machinery and spatiotemporally specific extrinsic inputs collaborate to control dynamics of cell movements and morphologies. Here we consider recent advances in our understanding of eye morphogenesis, with a focus on the mechanics of eye formation throughout vertebrate systems, including insights and potential opportunities using organoids, which may provide a tractable system to test hypotheses from embryonic models.
Topics: Actomyosin; Animals; Cell Movement; Eye; Humans; Lens, Crystalline; Morphogenesis; Optic Disk; Organogenesis; Retina; Retinal Pigment Epithelium; Signal Transduction; Vertebrates
PubMed: 33811855
DOI: 10.1016/j.ydbio.2021.03.023