593 research outputs found
Advances in Optical Coherence Tomography
Background: This review is dedicated to providing a comprehensive understanding of the foundational principles of OCT, tracing its progression from time-domain to Fourier-domain methodologies, and examining the substantial advancements that have profoundly transformed its role in ophthalmological diagnostics. Â
Material and Methods: Our methodology involves a comprehensive literature review. The review begins with a meticulous exploration of the fundamental principles of OCT, delving into its profound connection with the wave-like nature of light. We then proceed with an in-depth examination of the progression of OCT methodologies, tracing their journey from time-domain to Fourier-domain. This is followed by an exhaustive discussion of the most recent advancements in OCT technology, including the emergence of vis-OCT, AO-OCT, PS-OCT, High-Res OCT, and FFOCT. Â
Results: Since its inception, OCT has undergone several evolutions, with each advancement contributing to improved image resolution, increased acquisition speed, and enhanced imaging depth. These technological advancements have allowed for a more precise and early detection of various ocular conditions. Furthermore, innovations such as vis-OCT, AO-OCT, and others, have demonstrated their potential in expanding OCT's diagnostic capabilities. Â
Conclusions: The continual evolution and refinement of OCT technology underscore its critical role in enhancing our understanding of the eye's microstructure and contribute to more effective diagnostic strategies and targeted interventions for various ocular pathologies. As OCT technology continues to evolve, it promises an exciting future for eye care, with possibilities for even more advanced imaging techniques, better diagnostics, and improved patient care
Optic Neuropathies
Optic nerve can be affected by various etiologies of optic neuropathies, and it can appear swollen or pale depending on etiology and duration of the disease. These etiologies are inflammation, ischemia, malignancy, idiopathic intracranial hypertension, toxins, and nutritional deficiency. Peripapillary optical coherence tomography (OCT) is widely performed to detect these diseases and monitor them based on the changes in peripapillary retinal nerve fiber layer (RNFL) thickness. Therefore, nowadays this modality of imaging has become a routine test in follow-up of optic nerve diseases. In this chapter, clinical examinations and main findings of peripapillary OCT in common optic neuropathies are discussed
Optical Coherence Tomography in Retinopathy of Prematurity
Retinopathy of prematurity (ROP) is a disease that uniquely affects prematurely born infants. This disease is caused by disordered retinal vascular proliferation and may lead to blindness. The gold standard for ROP screening, diagnosis and monitoring is indirect ophthalmoscopy examination. Optical coherence tomography (OCT) has recently been used in ROP affected infants and children in research settings. It has provided further understanding of retinal vascular development and visualization of subtle subclinical features that otherwise go undetected. In school-aged children, OCT has become an essential tool for monitoring macular sequelae of ROP such as retained inner retinal layers, epiretinal membrane, subretinal fluid, and retinoschisis. This chapter reviews the current use of OCT in infants with ROP as well as older children with history of ROP
The Role of Optical Coherence Tomography Angiography in Glaucoma
Glaucoma is the second leading cause of blindness worldwide, affecting eighty million people globally and three million patients in the USA. Primary open-angle glaucoma, the most common type, is a multifactorial progressive optic nerve neurodegenerative disorder that leads to loss of optic nerve head (ONH) tissue, thinning of the retinal nerve fiber layer, and corresponding visual field (VF) defects with or without elevated intraocular pressure (IOP). Risk factors include older age, black or Hispanic race, elevated IOP, thin central corneal thickness, disk hemorrhage, and low ocular perfusion pressure. The two prevalent theories explaining glaucomatous damage are mechanical (elevated IOP) and vascular (compromised optic nerve perfusion). Current diagnostic methods, such as measuring IOP, VF testing, and ONH evaluation, are subjective and often unreliable. Optical coherence tomography angiography (OCTA) is a rapid, non-invasive imaging modality that provides 3-D, volumetric details of both the structure and vascular networks of the retina and optic nerve. Various researchers have shown that OCTA provides an accurate and objective evaluation of the retina and the optic nerve in glaucoma. This chapter describes the role of OCTA in managing patients with glaucoma
Morphofunctional Changes of the Retina and Optic Nerve in Optical Neuropathy of Various Genesis: A Literature Review
The retina is part of the central nervous system and has much in common with the brain’s physiological characteristics. Ophthalmological manifestations often precede the symptoms of central nervous system disorders and are used for their early diagnosis. Retinal imaging is simpler and more economical than the available central nervous system imaging methods. In this connection, the search for retinal biomarkers of neurodegenerative diseases is relevant. Optical coherence tomography is highly valuable both for routine clinical practice and for research purposes. Different patterns of structural changes of the optic nerve and retina in optical neuropathies of various genesis are due to differences in the pathogenesis of diseases (glaucoma optic neuropathy, non-arterial anterior ischemic optic neuropathy, optic neuritis associated with multiple sclerosis, and compression optic neuropathy). The identified biomarkers can be used for screening patients in primary healthcare institutions to provide a preliminary diagnosis of patients at risk
New OCT and OCTA Insights in Inherited Retinal Dystrophies
Optical coherence tomography (OCT) and OCT angiography (OCTA) radically changed the diagnostics of inherited retinal dystrophies (IRD), providing new information regarding the microstructural changes occurring in each disease. The introduction of quantitative metrics provided even more steps forward in the understanding of IRD pathogenesis and course, allowing to propose new ways to categorize different subgroups of patients, characterized by remarkably different characteristics and prognosis. All these informations provided insights regarding how heterogeneous the clinical spectrum of IRD is. In the present study, we provide an updated description of OCT and OCTA findings in the main IRD, including retinitis pigmentosa, Stargardt disease, and Best vitelliform macular dystrophy. Moreover, we discuss imaging findings in pigmented paravenous retinochoroidal atrophy, a rare condition that is undergoing even growing scientific and clinical interest. In addition, we provided a brief updated scenario on imaging findings in pattern dystrophies. We discuss in detail the current state-of-the-art and the new insights provided by quantitative OCT and OCTA approaches, offering a complete description that might be helpful both for expert and nonexpert researchers interested in IRD
New Technologies in Eye Surgery — A Challenge for Clinical, Therapeutic, and Eye Surgeons
Eye surgery is always progresses as the same way that the science advances. New emerging technologies such as bio-printing in 3D, developments and mathematical modeling in prototyping lab- on- a chip, visual implants, new biopolymers started to use in eye enucleation, detection of eye biomarkers at the cellular level, bio-sensors and new diagnostic tests should be considered to improve the quality of life of patients after surgery. This chapter provides a review of new and emerging technologies which are already working on global research centers. Emerging and converging technologies are terms used interchangeably to indicate the emergence and convergence of new technologies with demonstrated potential as disruptive technologies. Among them are: nanotechnology, biotechnology, information technology and communication, cognitive science, robotics, and artificial intelligence that have been launched as innovative products that promise to improve the quality of life and vision of patients with ocular compromised or low vision impairment. Some acronyms for these are: NBIC: Nanotechnology, Biotechnology, Information technology and Cognitive science. GNR: Genetics, Nanotechnology and Robotics. GRIN: Genetic, Robotic, Information, and Nanotechnology. BANG: Bits, Atoms, Neurons and Genes. Otherwise, to training ophthalmologist on news techniques, sophisticated simulation machines has been developing around the world
Role of OCT Angiography OCTA in the Diagnosis of Macular Diseases
OCT becomes an indispensable tool in everyday practice. OCTA is the functional extension that provides cross-sectional information on retinal and choroidal circulations without dye injection. It allows visualization of abnormal flow in areas with no flow and abnormal vessels (like CNVM). In ARMD, it can detect active membranes before being leaky in FFA. In diabetic retinopathy, OCTA can diagnose abnormal areas of non-perfusion in the superficial plexus, deeper capillary structures, or neovascularization. OCTA can detect focal dilation and foveal capillaries alterations in macular telangiectasia. It is useful in the diagnosis of inherited retinal diseases such as retinitis pigmentosa. OCTA has many challenges including longer acquisition times and motion artifacts. Longer wavelength SS-OCT may provide a solution for imaging through media opacities and a wider field of view. OCTA does not give full details about the retinal periphery, also, it gives no information about blood-retinal barrier (no dye to leak); an important sign in many retinal diseases
Optical Coherence Tomography Angiography (OCT-A): Emerging Landscapes in Neuro-Ophthalmology and Central Nervous System (CNS) Disorders
Optical Coherence Tomography (OCT) is now being widely used in several branches of biomedical science ranging from ophthalmology to neurology. Emerging from it, optical coherence tomography angiography (OCT-A) is a noninvasive, depth-resolved imaging tool for the visualization of retinal vascular changes. In the field of neuro-ophthalmology, OCT-A proves to be superior than the conventional Fluorescein angiography (FA) or indocyanine green angiography (ICGA). This chapter discussed the role of OCT-A in different neuro-ophthalmological and central nervous system (CNS) disorders including multiple sclerosis, non-arteritic anterior ischemic optic neuropathy (NAION), papilledema, papillitis, glaucoma, Parkinson’s disease, Alzheimer’s disease, cerebral small vessel diseases, and stroke. Since neuro-ophthalmological and some neurologic conditions show consistent peripapillary and macular capillary changes, OCT-A can be a future useful tool in a physician’s armamentarium due to its capability for better delineation of the superficial and deeper retinal and choroidal vasculatures. Furthermore, its limitations, technical challenges, and future research directions are illustrated in this chapter
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